Linaro-mm-sig

linaro-mm-sig@lists.linaro.org

2303 discussions

by Marek Szyprowski

Hello Everyone, This patchset introduces the proof-of-concept infrastructure for buffer sharing between multiple devices using file descriptors. The infrastructure has been integrated with V4L2 framework, more specifically videobuf2 and two S5P drivers FIMC (capture interface) and TV drivers, but it can be easily used by other kernel subsystems, like DRI. In this patch the buffer object has been simplified to absolute minimum - it contains only the buffer physical address (only physically contiguous buffers are supported), but this can be easily extended to complete scatter list in the future. Best regards -- Marek Szyprowski Samsung Poland R&D Center

12 years, 10 months

summit dial-in update

by Jesse Barker

Hi all, For those that tried to participate remotely yesterday, I have a couple of updates: 1) We've added an extra microphone in the middle of the room in the hopes of picking up the sound better. 2) We've gotten the room signed on to the correct IRC channel (#linaro-corpus). cheers, Jesse

12 years, 10 months

dial-in for cambourne sessions

by Jesse Barker

Hi all, Sorry for the late notice, but it turns out we have remote access for the memory management sessions at the Linaro Connect in Cambourne this week,, starting right now today, same time tomorrow and Wednesday. Dial-in details are available at http://connect.linaro.org/events/event/linux-on-arm/, the room is Corpus Christi, and the channel for the room is #connect-corpus. cheers, Jesse

12 years, 10 months

[PATCH/RFC 0/8] ARM: DMA-mapping framework redesign

by Marek Szyprowski

Hello, This patch series is a continuation of my works on implementing generic IOMMU support in DMA mapping framework for ARM architecture. Now I focused on the DMA mapping framework itself. It turned out that adding support for common dma_map_ops structure was not that hard as I initally thought. After some modification most of the code fits really well to the generic dma_map_ops methods. The only change required to dma_map_ops is a new alloc function. During the discussion on Linaro Memory Management meeting in Budapest we got the idea that we can have only one alloc/free/mmap function with additional attributes argument. This way all different kinds of architecture specific buffer mappings can be hidden behind the attributes without the need of creating several versions of dma_alloc_ function. I also noticed that the dma_alloc_noncoherent() function can be also implemented this way with DMA_ATTRIB_NON_COHERENT attribute. Systems that just defines dma_alloc_noncoherent as dma_alloc_coherent will just ignore such attribute. Another good use case for alloc methods with attributes is the possibility to allocate buffer without a valid kernel mapping. There are a number of drivers (mainly V4L2 and ALSA) that only exports the DMA buffers to user space. Such drivers don't touch the buffer data at all. For such buffers we can avoid the creation of a mapping in kernel virtual address space, saving precious vmalloc area. Such buffers might be allocated once a new attribute DMA_ATTRIB_NO_KERNEL_MAPPING. All the changes introduced in this patch series are intended to prepare a good ground for upcoming generic IOMMU integration to DMA mapping framework on ARM architecture. For more information about proof-of-concept IOMMU implementation in DMA mapping framework, please refer to my previous set of patches: http://www.spinics.net/lists/linux-mm/msg19856.html I've tried to split the redesign into a set of single-step changes for easier review and understanding. If there is anything that needs further clarification, please don't hesitate to ask. The patches are prepared on top of Linux Kernel v3.0-rc3. The proposed changes have been tested on Samsung Exynos4 platform. I've also tested dmabounce code (by manually registering support for DMA bounce for some of the devices available on my board), although my hardware have no such strict requirements. Would be great if one could test my patches on different ARM architectures to check if I didn't break anything. Best regards -- Marek Szyprowski Samsung Poland R&D Center Patch summary: Marek Szyprowski (8): ARM: dma-mapping: remove offset parameter to prepare for generic dma_ops ARM: dma-mapping: implement dma_map_single on top of dma_map_page ARM: dma-mapping: use asm-generic/dma-mapping-common.h ARM: dma-mapping: implement dma sg methods on top of generic dma ops ARM: dma-mapping: move all dma bounce code to separate dma ops structure ARM: dma-mapping: remove redundant code and cleanup common: dma-mapping: change alloc/free_coherent method to more generic alloc/free_attrs ARM: dma-mapping: use alloc, mmap, free from dma_ops arch/arm/Kconfig | 1 + arch/arm/common/dmabounce.c | 112 +++-- arch/arm/include/asm/device.h | 1 + arch/arm/include/asm/dma-mapping.h | 835 +++++++++++++----------------------- arch/arm/mm/dma-mapping.c | 278 +++++++------ include/linux/dma-attrs.h | 1 + include/linux/dma-mapping.h | 13 +- 7 files changed, 539 insertions(+), 702 deletions(-) rewrite arch/arm/include/asm/dma-mapping.h (66%) -- 1.7.1.569.g6f426

12 years, 10 months

[PATCHv12 0/8] Contiguous Memory Allocator

by Marek Szyprowski

Hello everyone, This is yet another round of Contiguous Memory Allocator patches. Now I focused mainly on the integration of CMA to DMA mapping subsystem on ARM architecture. In this version I've tried to solve the issue of the aliasing in coherent memory mapping that was present in earlier versions of DMA mapping framework. The proposed solution should be considered as a proof-of-concept. Right now it doesn't support GFP_ATOMIC allocations. Support for them is on my TODO list and will be implemented on top of the "ARM: DMA: steal memory for DMA coherent mappings" patch by Russell King. A few words for these who see CMA for the first time: The Contiguous Memory Allocator (CMA) makes it possible for device drivers to allocate big contiguous chunks of memory after the system has booted. The main difference from the similar frameworks is the fact that CMA allows to transparently reuse memory region reserved for the big chunk allocation as a system memory, so no memory is wasted when no big chunk is allocated. Once the alloc request is issued, the framework will migrate system pages to create a required big chunk of physically contiguous memory. For more information you can refer to nice LWN articles: http://lwn.net/Articles/447405/ and http://lwn.net/Articles/450286/ as well as links to previous versions of the CMA framework. The CMA framework has been initially developed by Michal Nazarewicz at Samsung Poland R&D Center. Since version 9, I've taken over the development, because Michal has left the company. The current version of CMA is a set of helper functions for DMA mapping framework that handles allocation of contiguous memory blocks. The difference between this patchset and Kamezawa's alloc_contig_pages() are: 1. alloc_contig_pages() requires MAX_ORDER alignment of allocations which may be unsuitable for embeded systems where a few MiBs are required. Lack of the requirement on the alignment means that several threads might try to access the same pageblock/page. To prevent this from happening CMA uses a mutex so that only one allocating/releasing function may run at one point. 2. CMA may use its own migratetype (MIGRATE_CMA) which behaves similarly to ZONE_MOVABLE but can be put in arbitrary places. This is required for us since we need to define two disjoint memory ranges inside system RAM. (ie. in two memory banks (do not confuse with nodes)). 3. alloc_contig_pages() scans memory in search for range that could be migrated. CMA on the other hand maintains its own allocator to decide where to allocate memory for device drivers and then tries to migrate pages from that part if needed. This is not strictly required but I somehow feel it might be faster. The integration with ARM DMA-mapping subsystem is done on 2 levels. During early boot memory reserved for contiguous areas are remapped with 2-level page tables. This enables us to change cache attributes of the individual pages from such area on request. Then, DMA mapping subsystem is updated to use dma_alloc_from_contiguous() call instead of alloc_pages() and perform page attributes remapping. Current version have been tested on Samsung S5PC110 based Goni machine and s5p-fimc V4L2 driver. The driver itself uses videobuf2 dma-contig memory allocator, which in turn relies on dma_alloc_coherent() from DMA-mapping subsystem. By integrating CMA with DMA-mapping we managed to get this driver working with CMA without any single change required in the driver or videobuf2-dma-contig allocator. TODO: - implement GPF_ATOMIC allocations - implement support for contiguous memory areas placed in HIGHMEM zone Best regards -- Marek Szyprowski Samsung Poland R&D Center Links to previous versions of the patchset: v11: <http://www.spinics.net/lists/linux-mm/msg21868.html> v10: <http://www.spinics.net/lists/linux-mm/msg20761.html> v9: <http://article.gmane.org/gmane.linux.kernel.mm/60787> v8: <http://article.gmane.org/gmane.linux.kernel.mm/56855> v7: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v6: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: <http://article.gmane.org/gmane.linux.kernel.mm/52010> v3: <http://article.gmane.org/gmane.linux.kernel.mm/51573> v2: <http://article.gmane.org/gmane.linux.kernel.mm/50986> v1: <http://article.gmane.org/gmane.linux.kernel.mm/50669> Changelog: v12: 1. Fixed 2 nasty bugs in dma-contiguous allocator: - alignment argument was not passed correctly - range for dma_release_from_contiguous was not checked correctly 2. Added support for architecture specfic dma_contiguous_early_fixup() function 3. CMA and DMA-mapping integration for ARM architechture has been rewritten to take care of the memory aliasing issue that might happen for newer ARM CPUs (mapping of the same pages with different cache attributes is forbidden). TODO: add support for GFP_ATOMIC allocations basing on the "ARM: DMA: steal memory for DMA coherent mappings" patch and implement support for contiguous memory areas that are placed in HIGHMEM zone v11: 1. Removed genalloc usage and replaced it with direct calls to bitmap_* functions, dropped patches that are not needed anymore (genalloc extensions) 2. Moved all contiguous area management code from mm/cma.c to drivers/base/dma-contiguous.c 3. Renamed cm_alloc/free to dma_alloc/release_from_contiguous 4. Introduced global, system wide (default) contiguous area configured with kernel config and kernel cmdline parameters 5. Simplified initialization to just one function: dma_declare_contiguous() 6. Added example of device private memory contiguous area v10: 1. Rebased onto 3.0-rc2 and resolved all conflicts 2. Simplified CMA to be just a pure memory allocator, for use with platfrom/bus specific subsystems, like dma-mapping. Removed all device specific functions are calls. 3. Integrated with ARM DMA-mapping subsystem. 4. Code cleanup here and there. 5. Removed private context support. v9: 1. Rebased onto 2.6.39-rc1 and resolved all conflicts 2. Fixed a bunch of nasty bugs that happened when the allocation failed (mainly kernel oops due to NULL ptr dereference). 3. Introduced testing code: cma-regions compatibility layer and videobuf2-cma memory allocator module. v8: 1. The alloc_contig_range() function has now been separated from CMA and put in page_allocator.c. This function tries to migrate all LRU pages in specified range and then allocate the range using alloc_contig_freed_pages(). 2. Support for MIGRATE_CMA has been separated from the CMA code. I have not tested if CMA works with ZONE_MOVABLE but I see no reasons why it shouldn't. 3. I have added a @private argument when creating CMA contexts so that one can reserve memory and not share it with the rest of the system. This way, CMA acts only as allocation algorithm. v7: 1. A lot of functionality that handled driver->allocator_context mapping has been removed from the patchset. This is not to say that this code is not needed, it's just not worth posting everything in one patchset. Currently, CMA is "just" an allocator. It uses it's own migratetype (MIGRATE_CMA) for defining ranges of pageblokcs which behave just like ZONE_MOVABLE but dispite the latter can be put in arbitrary places. 2. The migration code that was introduced in the previous version actually started working. v6: 1. Most importantly, v6 introduces support for memory migration. The implementation is not yet complete though. Migration support means that when CMA is not using memory reserved for it, page allocator can allocate pages from it. When CMA wants to use the memory, the pages have to be moved and/or evicted as to make room for CMA. To make it possible it must be guaranteed that only movable and reclaimable pages are allocated in CMA controlled regions. This is done by introducing a MIGRATE_CMA migrate type that guarantees exactly that. Some of the migration code is "borrowed" from Kamezawa Hiroyuki's alloc_contig_pages() implementation. The main difference is that thanks to MIGRATE_CMA migrate type CMA assumes that memory controlled by CMA are is always movable or reclaimable so that it makes allocation decisions regardless of the whether some pages are actually allocated and migrates them if needed. The most interesting patches from the patchset that implement the functionality are: 09/13: mm: alloc_contig_free_pages() added 10/13: mm: MIGRATE_CMA migration type added 11/13: mm: MIGRATE_CMA isolation functions added 12/13: mm: cma: Migration support added [wip] Currently, kernel panics in some situations which I am trying to investigate. 2. cma_pin() and cma_unpin() functions has been added (after a conversation with Johan Mossberg). The idea is that whenever hardware does not use the memory (no transaction is on) the chunk can be moved around. This would allow defragmentation to be implemented if desired. No defragmentation algorithm is provided at this time. 3. Sysfs support has been replaced with debugfs. I always felt unsure about the sysfs interface and when Greg KH pointed it out I finally got to rewrite it to debugfs. v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: 1. The "asterisk" flag has been removed in favour of requiring that platform will provide a "*=<regions>" rule in the map attribute. 2. The terminology has been changed slightly renaming "kind" to "type" of memory. In the previous revisions, the documentation indicated that device drivers define memory kinds and now, v3: 1. The command line parameters have been removed (and moved to a separate patch, the fourth one). As a consequence, the cma_set_defaults() function has been changed -- it no longer accepts a string with list of regions but an array of regions. 2. The "asterisk" attribute has been removed. Now, each region has an "asterisk" flag which lets one specify whether this region should by considered "asterisk" region. 3. SysFS support has been moved to a separate patch (the third one in the series) and now also includes list of regions. v2: 1. The "cma_map" command line have been removed. In exchange, a SysFS entry has been created under kernel/mm/contiguous. The intended way of specifying the attributes is a cma_set_defaults() function called by platform initialisation code. "regions" attribute (the string specified by "cma" command line parameter) can be overwritten with command line parameter; the other attributes can be changed during run-time using the SysFS entries. 2. The behaviour of the "map" attribute has been modified slightly. Currently, if no rule matches given device it is assigned regions specified by the "asterisk" attribute. It is by default built from the region names given in "regions" attribute. 3. Devices can register private regions as well as regions that can be shared but are not reserved using standard CMA mechanisms. A private region has no name and can be accessed only by devices that have the pointer to it. 4. The way allocators are registered has changed. Currently, a cma_allocator_register() function is used for that purpose. Moreover, allocators are attached to regions the first time memory is registered from the region or when allocator is registered which means that allocators can be dynamic modules that are loaded after the kernel booted (of course, it won't be possible to allocate a chunk of memory from a region if allocator is not loaded). 5. Index of new functions: +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, size_t size, + dma_addr_t alignment) +static inline int +cma_info_about(struct cma_info *info, const const char *regions) +int __must_check cma_region_register(struct cma_region *reg); +dma_addr_t __must_check +cma_alloc_from_region(struct cma_region *reg, + size_t size, dma_addr_t alignment); +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, + size_t size, dma_addr_t alignment); +int cma_allocator_register(struct cma_allocator *alloc); Patches in this patchset: mm: move some functions from memory_hotplug.c to page_isolation.c mm: alloc_contig_freed_pages() added Code "stolen" from Kamezawa. The first patch just moves code around and the second provide function for "allocates" already freed memory. mm: alloc_contig_range() added This is what Kamezawa asked: a function that tries to migrate all pages from given range and then use alloc_contig_freed_pages() (defined by the previous commit) to allocate those pages. mm: MIGRATE_CMA migration type added mm: MIGRATE_CMA isolation functions added Introduction of the new migratetype and support for it in CMA. MIGRATE_CMA works similar to ZONE_MOVABLE expect almost any memory range can be marked as one. mm: cma: Contiguous Memory Allocator added The code CMA code. Manages CMA contexts and performs memory allocations. ARM: integrate CMA with dma-mapping subsystem Main client of CMA frame work. CMA serves as a alloc_pages() replacement. ARM: S5PV210: example of CMA private area for FIMC device on Goni board Example of platform/board specific code that creates cma context and assigns it to particular device. Patch summary: KAMEZAWA Hiroyuki (2): mm: move some functions from memory_hotplug.c to page_isolation.c mm: alloc_contig_freed_pages() added Marek Szyprowski (3): drivers: add Contiguous Memory Allocator ARM: integrate CMA with dma-mapping subsystem ARM: S5PV210: example of CMA private area for FIMC device on Goni board Michal Nazarewicz (3): mm: alloc_contig_range() added mm: MIGRATE_CMA migration type added mm: MIGRATE_CMA isolation functions added arch/Kconfig | 3 + arch/arm/Kconfig | 1 + arch/arm/include/asm/device.h | 3 + arch/arm/include/asm/dma-contiguous.h | 33 +++ arch/arm/include/asm/mach/map.h | 1 + arch/arm/mach-s5pv210/Kconfig | 1 + arch/arm/mach-s5pv210/mach-goni.c | 8 + arch/arm/mm/dma-mapping.c | 244 +++----------------- arch/arm/mm/init.c | 3 + arch/arm/mm/mmu.c | 56 +++++- drivers/base/Kconfig | 77 +++++++ drivers/base/Makefile | 1 + drivers/base/dma-contiguous.c | 396 +++++++++++++++++++++++++++++++++ include/linux/dma-contiguous.h | 102 +++++++++ include/linux/mmzone.h | 41 +++- include/linux/page-isolation.h | 51 ++++- mm/Kconfig | 8 +- mm/compaction.c | 10 + mm/memory_hotplug.c | 111 --------- mm/page_alloc.c | 287 ++++++++++++++++++++++-- mm/page_isolation.c | 129 ++++++++++- 21 files changed, 1197 insertions(+), 369 deletions(-) create mode 100644 arch/arm/include/asm/dma-contiguous.h create mode 100644 drivers/base/dma-contiguous.c create mode 100644 include/linux/dma-contiguous.h -- 1.7.1.569.g6f426

12 years, 10 months

[RFC 2/2] ARM: initial proof-of-concept IOMMU mapper for DMA-mapping

by Ramirez Luna, Omar

Hi Marek, > Add initial proof of concept implementation of DMA-mapping API for > devices that have IOMMU support. Right now only dma_alloc_coherent, > dma_free_coherent and dma_mmap_coherent functions are supported. > > Signed-off-by: Marek Szyprowski <m.szyprowski(a)samsung.com> > Signed-off-by: Kyungmin Park <kyungmin.park(a)samsung.com> > --- ... > diff --git a/arch/arm/include/asm/dma-iommu.h b/arch/arm/include/asm/dma-iommu.h > new file mode 100644 > index 0000000..c246ff3 > --- /dev/null > +++ b/arch/arm/include/asm/dma-iommu.h ... > +int __init arm_iommu_assign_device(struct device *dev, dma_addr_t base, dma_addr_t size); __init causes a panic if the iommu is assigned after boot. In OMAP3 the iommu driver controls isp and dsp address spaces, it is loaded until any of those 2 drivers is needed. > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index f8c6972..b6397c1 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c ... > +static void *arm_iommu_alloc_attrs(struct device *dev, size_t size, > + dma_addr_t *handle, gfp_t gfp, struct dma_attrs *attrs) > +{ > + struct dma_iommu_mapping *mapping = dev->archdata.mapping; > + struct page **pages; > + void *addr = NULL; > + pgprot_t prot; > + > + if (dma_get_attr(DMA_ATTR_WRITE_COMBINE, attrs)) > + prot = pgprot_writecombine(pgprot_kernel); > + else > + prot = pgprot_dmacoherent(pgprot_kernel); > + > + arm_iommu_init(dev); I found useful to call arm_iommu_init inside arm_iommu_assign_device instead. So, then gen_pool is created only once without the mapping->pool check, instead of relying on the call to ...alloc_attrs, which in my case I never use because I'm implementing iommu_map|unmap_sg functions to see how it goes with the dma mapping. Regards, Omar

12 years, 10 months

Re: [Linaro-mm-sig] [PATCH 00/10] mm: Linux VM Infrastructure to support Memory Power Management

by amit kachhap

Hi All, In response to the discussion about power savings with memory regions features following measurements are done. Title: On a system with 2GB memory , 1GB is static and the other 1GB in various power states. Brief environment description: Samsung smdk-exynos board is used for this work and full board level power consumption is measured that comprises of cpu and other components. It has 2 DMC's(Dynamic memory controller) with each supporting 1 GB DDR3 memory. Power characteristics of DMC0 controlled memory remain same but memory controlled by DMC1 is changed to 4 different power states. The following numbers describe the maximum power savings measured after executing the software from DMC0 controlled memory which changes the power states of DMC1 controlled memory. Here the actual numbers are not mentioned but the percentage power savings is shown in reference to the change in overall power consumption. The memory region patches are expected to facilitate transition of memory into into one of the following low power states. 1) Percentage power savings when DMC1(1GB) moved to self refresh mode from idle/unaccess mode= 2.69% 2) Percentage power savings when DMC1(1GB) moved to precharge mode from idle/unaccess mode= 3.23% 3) Percentage power savings when DMC1(1GB) clock is gated = 6.32% The above power savings is indicative of the benefits that memory regions could provide in this platform. Thanks & Regards, Amit Daniel Kachhap Samsung India s/w operations, Bangalore On Sat, May 28, 2011 at 1:26 PM, Andrew Morton <akpm(a)linux-foundation.org> wrote: > On Fri, 27 May 2011 18:01:28 +0530 Ankita Garg <ankita(a)in.ibm.com> wrote: > >> This patchset proposes a generic memory regions infrastructure that can be >> used to tag boundaries of memory blocks which belongs to a specific memory >> power management domain and further enable exploitation of platform memory >> power management capabilities. > > A couple of quick thoughts... > > I'm seeing no estimate of how much energy we might save when this work > is completed. But saving energy is the entire point of the entire > patchset! So please spend some time thinking about that and update and > maintain the [patch 0/n] description so others can get some idea of the > benefit we might get from all of this. That estimate should include an > estimate of what proportion of machines are likely to have hardware > which can use this feature and in what timeframe. > > IOW, if it saves one microwatt on 0.001% of machines, not interested ;) > > > Also, all this code appears to be enabled on all machines? So machines > which don't have the requisite hardware still carry any additional > overhead which is added here. I can see that ifdeffing a feature like > this would be ghastly but please also have a think about the > implications of this and add that discussion also. > > If possible, it would be good to think up some microbenchmarks which > probe the worst-case performance impact and describe those and present > the results. So others can gain an understanding of the runtime costs. > > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel(a)lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >

12 years, 10 months

[PATCHv10 0/10] Contiguous Memory Allocator

by Marek Szyprowski

Hello everyone, Like I've promised during the Memory Management summit at Linaro Meeting in Budapest I continued the development of the CMA. The goal is to integrate it as tight as possible with other kernel subsystems (like memory management and dma-mapping) and finally merge to mainline. This version introduces integration with DMA-mapping subsystem for ARM architecture, but I believe that similar integration can be done for other archs too. I've also rebased all the code onto latest v3.0-rc2 kernel. A few words for these who see CMA for the first time: The Contiguous Memory Allocator (CMA) makes it possible for device drivers to allocate big contiguous chunks of memory after the system has booted. The main difference from the similar frameworks is the fact that CMA allows to transparently reuse memory region reserved for the big chunk allocation as a system memory, so no memory is wasted when no big chunk is allocated. Once the alloc request is issued, the framework will migrate system pages to create a required big chunk of physically contiguous memory. For more information see the changelog and links to previous versions of CMA framework. The current version of CMA is just an allocator that handles allocation of contiguous memory blocks. The difference between this patchset and Kamezawa's alloc_contig_pages() are: 1. alloc_contig_pages() requires MAX_ORDER alignment of allocations which may be unsuitable for embeded systems where a few MiBs are required. Lack of the requirement on the alignment means that several threads might try to access the same pageblock/page. To prevent this from happening CMA uses a mutex so that only one cm_alloc()/cm_free() function may run at one point. 2. CMA may use its own migratetype (MIGRATE_CMA) which behaves similarly to ZONE_MOVABLE but can be put in arbitrary places. This is required for us since we need to define two disjoint memory ranges inside system RAM. (ie. in two memory banks (do not confuse with nodes)). 3. alloc_contig_pages() scans memory in search for range that could be migrated. CMA on the other hand maintains its own allocator to decide where to allocate memory for device drivers and then tries to migrate pages from that part if needed. This is not strictly required but I somehow feel it might be faster. The integration with ARM DMA-mapping subsystem is quite straightforward. Once cma context is available alloc_pages() can be replaced by cm_alloc() call. Current version have been tested on Samsung S5PC110 based Aquila machine and s5p-fimc V4L2 driver. The driver itself uses videobuf2 dma-contig memory allocator, which in turn relies on dma_alloc_coherent() from DMA-mapping subsystem. By integrating CMA with DMA-mapping we manage to get this driver working with CMA without any single change required in the driver or videobuf2-dma-contig allocator. TODO: 1. use struct page * or pfn internally instead of physicall address 2. use some simple bitmap based allocator instead of genaloc 3. provide a function similar to dma_declare_coherent_memory(), which will created and register cma area for particular device 4. code cleanup and simplification 5. discussion 6. double-mapping issues with ARMv6+ and coherent memory Best regards -- Marek Szyprowski Samsung Poland R&D Center Links to previous versions of the patchset: v9: <http://article.gmane.org/gmane.linux.kernel.mm/60787> v8: <http://article.gmane.org/gmane.linux.kernel.mm/56855> v7: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v6: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v5: (intentionally left out as CMA v5 was identical to CMA v4) lv4: <http://article.gmane.org/gmane.linux.kernel.mm/52010> v3: <http://article.gmane.org/gmane.linux.kernel.mm/51573> v2: <http://article.gmane.org/gmane.linux.kernel.mm/50986> v1: <http://article.gmane.org/gmane.linux.kernel.mm/50669> Changelog: v10: 1. Rebased onto 3.0-rc2 and resolved all conflicts 2. Simplified CMA to be just a pure memory allocator, for use with platfrom/bus specific subsystems, like dma-mapping. Removed all device specific functions are calls. 3. Integrated with ARM DMA-mapping subsystem. 4. Code cleanup here and there. 5. Removed private context support. v9: 1. Rebased onto 2.6.39-rc1 and resolved all conflicts 2. Fixed a bunch of nasty bugs that happened when the allocation failed (mainly kernel oops due to NULL ptr dereference). 3. Introduced testing code: cma-regions compatibility layer and videobuf2-cma memory allocator module. v8: 1. The alloc_contig_range() function has now been separated from CMA and put in page_allocator.c. This function tries to migrate all LRU pages in specified range and then allocate the range using alloc_contig_freed_pages(). 2. Support for MIGRATE_CMA has been separated from the CMA code. I have not tested if CMA works with ZONE_MOVABLE but I see no reasons why it shouldn't. 3. I have added a @private argument when creating CMA contexts so that one can reserve memory and not share it with the rest of the system. This way, CMA acts only as allocation algorithm. v7: 1. A lot of functionality that handled driver->allocator_context mapping has been removed from the patchset. This is not to say that this code is not needed, it's just not worth posting everything in one patchset. Currently, CMA is "just" an allocator. It uses it's own migratetype (MIGRATE_CMA) for defining ranges of pageblokcs which behave just like ZONE_MOVABLE but dispite the latter can be put in arbitrary places. 2. The migration code that was introduced in the previous version actually started working. v6: 1. Most importantly, v6 introduces support for memory migration. The implementation is not yet complete though. Migration support means that when CMA is not using memory reserved for it, page allocator can allocate pages from it. When CMA wants to use the memory, the pages have to be moved and/or evicted as to make room for CMA. To make it possible it must be guaranteed that only movable and reclaimable pages are allocated in CMA controlled regions. This is done by introducing a MIGRATE_CMA migrate type that guarantees exactly that. Some of the migration code is "borrowed" from Kamezawa Hiroyuki's alloc_contig_pages() implementation. The main difference is that thanks to MIGRATE_CMA migrate type CMA assumes that memory controlled by CMA are is always movable or reclaimable so that it makes allocation decisions regardless of the whether some pages are actually allocated and migrates them if needed. The most interesting patches from the patchset that implement the functionality are: 09/13: mm: alloc_contig_free_pages() added 10/13: mm: MIGRATE_CMA migration type added 11/13: mm: MIGRATE_CMA isolation functions added 12/13: mm: cma: Migration support added [wip] Currently, kernel panics in some situations which I am trying to investigate. 2. cma_pin() and cma_unpin() functions has been added (after a conversation with Johan Mossberg). The idea is that whenever hardware does not use the memory (no transaction is on) the chunk can be moved around. This would allow defragmentation to be implemented if desired. No defragmentation algorithm is provided at this time. 3. Sysfs support has been replaced with debugfs. I always felt unsure about the sysfs interface and when Greg KH pointed it out I finally got to rewrite it to debugfs. v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: 1. The "asterisk" flag has been removed in favour of requiring that platform will provide a "*=<regions>" rule in the map attribute. 2. The terminology has been changed slightly renaming "kind" to "type" of memory. In the previous revisions, the documentation indicated that device drivers define memory kinds and now, v3: 1. The command line parameters have been removed (and moved to a separate patch, the fourth one). As a consequence, the cma_set_defaults() function has been changed -- it no longer accepts a string with list of regions but an array of regions. 2. The "asterisk" attribute has been removed. Now, each region has an "asterisk" flag which lets one specify whether this region should by considered "asterisk" region. 3. SysFS support has been moved to a separate patch (the third one in the series) and now also includes list of regions. v2: 1. The "cma_map" command line have been removed. In exchange, a SysFS entry has been created under kernel/mm/contiguous. The intended way of specifying the attributes is a cma_set_defaults() function called by platform initialisation code. "regions" attribute (the string specified by "cma" command line parameter) can be overwritten with command line parameter; the other attributes can be changed during run-time using the SysFS entries. 2. The behaviour of the "map" attribute has been modified slightly. Currently, if no rule matches given device it is assigned regions specified by the "asterisk" attribute. It is by default built from the region names given in "regions" attribute. 3. Devices can register private regions as well as regions that can be shared but are not reserved using standard CMA mechanisms. A private region has no name and can be accessed only by devices that have the pointer to it. 4. The way allocators are registered has changed. Currently, a cma_allocator_register() function is used for that purpose. Moreover, allocators are attached to regions the first time memory is registered from the region or when allocator is registered which means that allocators can be dynamic modules that are loaded after the kernel booted (of course, it won't be possible to allocate a chunk of memory from a region if allocator is not loaded). 5. Index of new functions: +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, size_t size, + dma_addr_t alignment) +static inline int +cma_info_about(struct cma_info *info, const const char *regions) +int __must_check cma_region_register(struct cma_region *reg); +dma_addr_t __must_check +cma_alloc_from_region(struct cma_region *reg, + size_t size, dma_addr_t alignment); +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, + size_t size, dma_addr_t alignment); +int cma_allocator_register(struct cma_allocator *alloc); Patches in this patchset: lib: bitmap: Added alignment offset for bitmap_find_next_zero_area() lib: genalloc: Generic allocator improvements Some improvements to genalloc API (most importantly possibility to allocate memory with alignment requirement). mm: move some functions from memory_hotplug.c to page_isolation.c mm: alloc_contig_freed_pages() added Code "stolen" from Kamezawa. The first patch just moves code around and the second provide function for "allocates" already freed memory. mm: alloc_contig_range() added This is what Kamezawa asked: a function that tries to migrate all pages from given range and then use alloc_contig_freed_pages() (defined by the previous commit) to allocate those pages. mm: MIGRATE_CMA migration type added mm: MIGRATE_CMA isolation functions added Introduction of the new migratetype and support for it in CMA. MIGRATE_CMA works similar to ZONE_MOVABLE expect almost any memory range can be marked as one. mm: cma: Contiguous Memory Allocator added The code CMA code. Manages CMA contexts and performs memory allocations. ARM: integrate CMA with dma-mapping subsystem Main client of CMA frame work. CMA serves as a alloc_pages() replacement if device has the cma context assigned. ARM: S5PV210: add CMA support for FIMC devices on Aquila board Example of platform/board specific code that creates cma context and assigns it to particular devices. Patch summary: KAMEZAWA Hiroyuki (2): mm: move some functions from memory_hotplug.c to page_isolation.c mm: alloc_contig_freed_pages() added Marek Szyprowski (3): mm: cma: Contiguous Memory Allocator added ARM: integrate CMA with dma-mapping subsystem ARM: S5PV210: add CMA support for FIMC devices on Aquila board Michal Nazarewicz (5): lib: bitmap: Added alignment offset for bitmap_find_next_zero_area() lib: genalloc: Generic allocator improvements mm: alloc_contig_range() added mm: MIGRATE_CMA migration type added mm: MIGRATE_CMA isolation functions added arch/arm/include/asm/device.h | 3 + arch/arm/include/asm/dma-mapping.h | 19 ++ arch/arm/mach-s5pv210/Kconfig | 1 + arch/arm/mach-s5pv210/mach-aquila.c | 26 +++ arch/arm/mm/dma-mapping.c | 60 +++++-- include/linux/bitmap.h | 24 ++- include/linux/cma.h | 189 ++++++++++++++++++ include/linux/genalloc.h | 50 +++--- include/linux/mmzone.h | 43 ++++- include/linux/page-isolation.h | 50 ++++-- lib/bitmap.c | 22 ++- lib/genalloc.c | 190 +++++++++++-------- mm/Kconfig | 29 +++- mm/Makefile | 1 + mm/cma.c | 358 +++++++++++++++++++++++++++++++++++ mm/compaction.c | 10 + mm/internal.h | 3 + mm/memory_hotplug.c | 111 ----------- mm/page_alloc.c | 292 ++++++++++++++++++++++++++--- mm/page_isolation.c | 130 ++++++++++++- 20 files changed, 1319 insertions(+), 292 deletions(-) create mode 100644 include/linux/cma.h create mode 100644 mm/cma.c -- 1.7.1.569.g6f426

12 years, 11 months

Reminder: Next face to face

by Jesse Barker

Hi all, Just a reminder (as previously discussed in Budapest and in the recent IRC meeting), the next face to face mini-summit will be at the Linaro Connect event from August 1-5 in Cambourne, UK (just outside Cambridge). The actual mini-summit will be, as with Budapest, afternoons on Monday through Wednesday. We will also be co-locating the next V4L2 brainstorming meeting at the Connect as well (right, Laurent?). Details for registering, booking the conference hotel, etc. can be found here: https://wiki.linaro.org/Events/LinaroConnectQ3.11 Please let me know if you have questions, concerns, etc. cheers, Jesse

12 years, 11 months

[RFC 0/2] ARM: DMA-mapping & IOMMU integration

by Marek Szyprowski

Hello, Folloing the discussion about the driver for IOMMU controller for Samsung Exynos4 platform and Arnd's suggestions I've decided to start working on redesign of dma-mapping implementation for ARM architecture. The goal is to add support for IOMMU in the way preffered by the community :) Some of the ideas about merging dma-mapping api and iommu api comes from the following threads: http://www.spinics.net/lists/linux-media/msg31453.html http://www.spinics.net/lists/arm-kernel/msg122552.html http://www.spinics.net/lists/arm-kernel/msg124416.html They were also discussed on Linaro memory management meeting at UDS (Budapest 9-12 May). I've finaly managed to clean up a bit my works and present the initial, very proof-of-concept version of patches that were ready just before Linaro meeting. What have been implemented: 1. Introduced arm_dma_ops dma_map_ops from include/linux/dma-mapping.h suffers from the following limitations: - lack of start address for sync operations - lack of write-combine methods - lack of mmap to user-space methods - lack of map_single method For the initial version I've decided to use custom arm_dma_ops. Extending common interface will take time, until that I wanted to have something already working. dma_{alloc,free,mmap}_{coherent,writecombine} have been consolidated into dma_{alloc,free,mmap}_attrib what have been suggested on Linaro meeting. New attribute for WRITE_COMBINE memory have been introduced. 2. moved all inline ARM dma-mapping related operations to arch/arm/mm/dma-mapping.c and put them as methods in generic arm_dma_ops structure. The dma-mapping.c code deinitely needs cleanup, but this is just a first step. 3. Added very initial IOMMU support. Right now it is limited only to dma_alloc_attrib, dma_free_attrib and dma_mmap_attrib. It have been tested with s5p-fimc driver on Samsung Exynos4 platform. 4. Adapted Samsung Exynos4 IOMUU driver to make use of the introduced iommu_dma proposal. This patch series contains only patches for common dma-mapping part. There is also a patch that adds driver for Samsung IOMMU controller on Exynos4 platform. All required patches are available on: git://git.infradead.org/users/kmpark/linux-2.6-samsung dma-mapping branch Git web interface: http://git.infradead.org/users/kmpark/linux-2.6-samsung/shortlog/refs/heads… Future: 1. Add all missing operations for IOMMU mappings (map_single/page/sg, sync_*) 2. Move sync_* operations into separate function for better code sharing between iommu and non-iommu dma-mapping code 3. Splitting out dma bounce code from non-bounce into separate set of dma methods. Right now dma-bounce code is compiled conditionally and spread over arch/arm/mm/dma-mapping.c and arch/arm/common/dmabounce.c. 4. Merging dma_map_single with dma_map_page. I haven't investigated deeply why they have separate implementation on ARM. If this is a requirement then dma_map_ops need to be extended with another method. 5. Fix dma_alloc to unmap from linear mapping. 6. Convert IO address space management code from gen-alloc to some simpler bitmap based solution. 7. resolve issues that might araise during discussion & comments Please note that this is very early version of patches, definitely NOT intended for merging. I just wanted to make sure that the direction is right and share the code with others that might want to cooperate on dma-mapping improvements. Best regards -- Marek Szyprowski Samsung Poland R&D Center Patch summary: Marek Szyprowski (2): ARM: Move dma related inlines into arm_dma_ops methods ARM: initial proof-of-concept IOMMU mapper for DMA-mapping arch/arm/Kconfig | 1 + arch/arm/include/asm/device.h | 3 + arch/arm/include/asm/dma-iommu.h | 30 ++ arch/arm/include/asm/dma-mapping.h | 653 +++++++++++------------------ arch/arm/mm/dma-mapping.c | 817 +++++++++++++++++++++++++++++++++--- arch/arm/mm/vmregion.h | 2 +- include/linux/dma-attrs.h | 1 + 7 files changed, 1033 insertions(+), 474 deletions(-) create mode 100644 arch/arm/include/asm/dma-iommu.h -- 1.7.1.569.g6f426

12 years, 11 months

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