linaro-kernel March 2012

linaro-kernel@lists.linaro.org

38 participants
53 discussions

by Arnd Bergmann

We've had a discussion in the Linaro storage team (Saugata, Venkat and me, with Luca joining in on the discussion) about swapping to flash based media such as eMMC. This is a summary of what we found and what we think should be done. If people agree that this is a good idea, we can start working on it. The basic problem is that Linux without swap is sort of crippled and some things either don't work at all (hibernate) or not as efficient as they should (e.g. tmpfs). At the same time, the swap code seems to be rather inappropriate for the algorithms used in most flash media today, causing system performance to suffer drastically, and wearing out the flash hardware much faster than necessary. In order to change that, we would be implementing the following changes: 1) Try to swap out multiple pages at once, in a single write request. My reading of the current code is that we always send pages one by one to the swap device, while most flash devices have an optimum write size of 32 or 64 kb and some require an alignment of more than a page. Ideally we would try to write an aligned 64 kb block all the time. Writing aligned 64 kb chunks often gives us ten times the throughput of linear 4kb writes, and going beyond 64 kb usually does not give any better performance. 2) Make variable sized swap clusters. Right now, the swap space is organized in clusters of 256 pages (1MB), which is less than the typical erase block size of 4 or 8 MB. We should try to make the swap cluster aligned to erase blocks and have the size match to avoid garbage collection in the drive. The cluster size would typically be set by mkswap as a new option and interpreted at swapon time. 3) As Luca points out, some eMMC media would benefit significantly from having discard requests issued for every page that gets freed from the swap cache, rather than at the time just before we reuse a swap cluster. This would probably have to become a configurable option as well, to avoid the overhead of sending the discard requests on media that don't benefit from this. Does this all sound appropriate for the Linux memory management people? Also, does this sound useful to the Android developers? Would you start using swap if we make it perform well and not destroy the drives? Finally, does this plan match up with the capabilities of the various eMMC devices? I know more about SD and USB devices and I'm quite convinced that it would help there, but eMMC can be more like an SSD in some ways, and the current code should be fine for real SSDs. Arnd

11 years, 9 months

[ACTIVITY] ... for the last 2 months (!)

by Nicolas Pitre

[ Yeah OK... I'm really bad with this stuff. ] January 23 to FEbruary 03 - More on-going study of the standalone b.L switcher code. - Discussion with Le.chi Thu, Paul Larson and others about big.LITTLE switcher testing requirements. - Involved in the review cycle for a patch about the new generic ioremap optimization from Pawel Moll which turned out to be bad and needed a subsequent revert. - Obtaining and setting up the b.L Fast Model license. - Review of some RCU changes pushed down the platform idle code path by Paul E. McKenney which I ended up NAKing. - Review of a patch from Stephen Boyd to disable preemption when reading CCSIDR on ARMv7 to which I suggested a simpler alternative. - Review of the initial test plan for the big.LITTLE switcher. - REview of the SA11x0 cleanups from RMK. - Investigation and prodding sent to Andrew Lunn for fixing a few Kirkwood breakages from recent consolidation changes. - More design discussions around b.L switcher with people from ARM Ltd, notably Robin Randhawa. - Preparing for Linaro Connect. February 06 to 10 - Attending Linaro Connect. - REview of Rob Herring's series cleaning up and removing IRQ and FIQ related macros from the kernel. - Wrote an article about big.LITTLE switcher for LWN. - REview of Marc Zyngier's series to add per SoC SMP and CPU hotplug operations. - Quickstart session with Dave Martin to run the ARM Fast Model for b.L. February 13 to 24 - Refinement to my LWN article about b.L before publication. - Review of a patch series preparing the kernel for being entered in hypervisor mode by Dave Martin. - Discussion (on IRC) between Dave Martin and myself about design changes brought to the in-kernel b.L switcher. - Start experimenting with the b.L fast model. - Read and digested various documents about the ARM virtualization, the GIC, etc. - Produced some b.L project status to help project management transition from Usman to Mounir. - Posted a patch to add support for early console output via semihosting. - Wrote the first part of the big.LITTLE write-up for the monthly member report (Paul McKenney did the second part). February 27 to March 02 - Away on vacation. March 05 to 16 - Review of the initial Kirkwood conversion to FDT by jason(a)lakedaemon.net. - Review of a patch series removing most instances of io.h by Rob Herring. - Comments/suggestions on how to deal with unresponsive maintainers, prompted by Amit Kucheria. - Review of a patch by Stephen Warren to generalize u-Boot's uImage wrapping in the kernel build. - More experiments with the b.L software model, attempting to boot a 8-core SMP system, running into cross cluster cache coherency problems. Finally get it to boot, thanks to the ARM guys who provided the missing clue. - Look at the multi-cluster aware boot protocol patches by Lorenzo Pieralisi. Some of it might be directly useful for the b.L switcher. - Review of Dave Martin's patch series to facilitate custom opcode injection. - Improved a patch I posted months ago to remove the debugging restrictions inside the devicemaps_init() function and pushed upstream. REcent changes to the kernel are making this patch very useful for people to debug their own kernel. - Quick review of the Cortex-M3 support by Uwe Kleine-König. - Moved to the arm-soc tree to implement the in-kernel switcher as it contains everything to boot a vexpress config with device tree on the software model. Nicolas

11 years, 11 months

[PATCH] staging: android/ram_console: Don't build on arches w/o ioremap

by Anton Vorontsov

This patch fixes UML build: CC drivers/staging/android/ram_console.o drivers/staging/android/ram_console.c: In function 'ram_console_driver_probe': drivers/staging/android/ram_console.c:358:2: error: implicit declaration of function 'ioremap' [-Werror=implicit-function-declaration] cc1: some warnings being treated as errors make[3]: *** [drivers/staging/android/ram_console.o] Error 1 Signed-off-by: Anton Vorontsov <anton.vorontsov(a)linaro.org> --- drivers/staging/android/Kconfig | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/drivers/staging/android/Kconfig b/drivers/staging/android/Kconfig index becf711..2054ccb 100644 --- a/drivers/staging/android/Kconfig +++ b/drivers/staging/android/Kconfig @@ -27,6 +27,7 @@ config ANDROID_LOGGER config ANDROID_RAM_CONSOLE bool "Android RAM buffer console" + depends on !S390 && !UML default n config ANDROID_RAM_CONSOLE_ENABLE_VERBOSE -- 1.7.7.6

12 years

linux-linaro on IMX53QSB

by Eric Bénard

Hi Eric, while testing the Quick Start Board, I quickly tried several kernel built from git://git.linaro.org/bsp/freescale/linux-linaro.git - lt-3.2-imx5 : needs some fixes to build, boots but X fails to run (with 11.09.01 BSP's userland on the VGA output) - lt-3.2-imx6: needs some fixes to build, fails to boot - lt-3.1-2011.12: don't remember the result - rel_imx_2.6.38_12.01.01 : fails to boot I can provide log & more details for each configuration later if needed. The instructions on the Wiki ( https://wiki.linaro.org/Boards/MX53QuickStart ) seems outdated. Is this platform still supported by Linaro ? What is the Freescale Landing team's recommended tag to use to test linux-linaro on iMX53QSB ? What are the recommended GPU & VPU libraries to use to get the best of the i.MX53 with linux-linaro ? Thanks Eric -- http://eukrea.com/en/news/104-2012

12 years

[ACTIVITY] (Deepak Saxena) March 25 - 31

by Deepak Saxena

== Deepak Saxena <dsaxena> == === Highlights === * Worked on article on "Kernel Upstreaming Challenges" for executive member update. Ended up writing one version and completely throwing it away as it was too introductory but hope to use that to write a larger white-paper type of document on the topic. Update article draft @ http://goo.gl/9SBpT. * Self-review, engineer review. (Do we really need to do these every 3-4 months?) * Worked with Mounir on 12.04 blueprint updates * Submitted talk proposal on "One zImage to Rule Them All" to LinuxCon Japan * Regular 1:1s and meetings === Plans === * Finish review cycle work * Finish patch tracking spreadsheet for upstream kernel work * Connect planning * Roadmap cards === Issues === * No major ones, though still feeling behind on everything due to being sick earlier in the month. :/ === Travel/Time Off === * Off May 4th and following week, back to work on Monday the 13th. Will have no interwebs and limited phone access. * Connect Q2, possibly with follow up

12 years

[ACTIVITY] (Rajendra Nayak) Mar 19 - Mar 30

by Rajendra Nayak

== Rajendra Nayak <rnayak> == === Highlights === * Worked on patches to make OMAP transition to common clk one SoC family at a time and also maintaining git-bisect. Turned out much ugly than I initially thought. Shared the patches along with a few minor fixes with Mike. * Started working on optimizing (reducing) OMAP4 common clk data on top of Mikes' initial work. Mostly done manual cleanups for now. Need to update the autogen scripts. * Started validating OMAP5 common clk using Mikes' framework changes and autogen updates. === Plans === * Autogen updates for OMAP4 data, OMAP5 validation and fixes to framework changes. === Misc === * Planning to take off on 2,9,10 April due to some personal emergency travel.

12 years

[ACTIVITY](John Stultz) Mar 26-30

by John Stultz

=== Highlights === * Sent out last bits of timekeeping changes for 3.4 & got them merged. * Spent a bit of time re-installing & reconfiguring my system environment per new internal policies: http://www.codinghorror.com/.a/6a0120a85dcdae970b016301e98de2970d-800wi * Sent out first pass at config fragment integration into the linaro kernel. Got some good feedback & patches from Tixy and Tushar. * Ran Android Subteam phone meeting & set up recurring phone meeting biweekly. * Reviewed Danial Walkers performance comparision between shm based and android logger based logging. Got into a longish discussion off-list discussion with him about Android's design requirements. Hopefully will see another iteration from Daniel. * At Tixy's prodding, contacted Dima to see about the earlysuspend removal in 3.3 and what fixes for the log flooding that caused are recommended. Got a quick response that they have a fix, and are looking to push it out soon. Tixy suggested a fix in the meantime. * Did a first pass fwd port of the Android 3.3 patch stack to 3.4. Messed up some of the mmc items and will likely have to try again. * Got a first pass at reworking the fadvise volatile code to store tree roots in a hash rather then bloat the address_space structure. It seems to be working, but I kind of don't believe it. === Plans === * More testing on fadvise volatile hash rework & send to lkml * Get all of Tushar's changes merged into the config fragment tree * Take another shot at fwd porting the Android tree to 3.4 === Issues === * NA

12 years

[ACTIVITY] (Arnd Bergmann) March 19 - March 30th

by Arnd Bergmann

== Arnd Bergmann == === Highlights === * Merge window, part two: everything we had queued is now in mainline * Discussed swap on flash with a few people, sent out first proposal * Continued DT discussion for spear, kirkwood, shmobile === Plans === * more review for DT conversions * regression testing post merge window * getting my build server back running * dig out my CONFIG_NO_IOPORT patch set and get that into linux-next

12 years

[ACTIVITY] (Venkatraman S) March 19 - March 30th

by Venkatraman S

== Venkatraman S svenkatr == == Highlights == * Sent out pull request for UFS and eMMC features for Linaro Kernel release * Coding up eMMC foreground HPI code. Sent a rough first cut to Storage folks. * Studies UFS implementation. Plan to abstract out the PCI specific part of driver files == Plans == * More HPI coding and do some stress tests * Test eMMC Power off notify with OMAP. == Misc == * Was on leave for 2 days

12 years

[ACTIVITY] (Saugata Das) March 26th - March 30th

by Saugata Das

== Saugata Das sdas == === Activity Summary === * Tested cases for < 4KB sector and EFI partition, with native sector support patch (https://blueprints.launchpad.net/linux-linaro/+spec/emmc4.5-native-sector) * Power OFF notify patch submitted === Plans === * Work on context ID patch (https://blueprints.launchpad.net/linux-linaro/+spec/emmc4.5-context-id) * Submit a proposal on the implementation of large block size (https://blueprints.launchpad.net/linux-linaro/+spec/vfs-larger-than-4k-bloc…) === Issues === * None

12 years

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linaro-kernel March 2012