The patch titled Subject: zram: introduce ZRAM_IDLE flag has been added to the -mm tree. Its filename is zram-introduce-zram_idle-flag.patch
This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/zram-introduce-zram_idle-flag.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/zram-introduce-zram_idle-flag.patch
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------------------------------------------------------ From: Minchan Kim minchan@kernel.org Subject: zram: introduce ZRAM_IDLE flag
To support idle page writeback with upcoming patches, this patch introduces a new ZRAM_IDLE flag.
Userspace can mark zram slots as "idle" via "echo all > /sys/block/zramX/idle" which marks every allocated zram slot as ZRAM_IDLE. User could see it by /sys/kernel/debug/zram/zram0/block_state.
300 75.033841 ...i 301 63.806904 s..i 302 63.806919 ..hi
Once there is IO for the slot, the mark will be disappeared.
300 75.033841 ... 301 63.806904 s..i 302 63.806919 ..hi
Therefore, 300th block is idle zpage. With this feature, user can how many zram has idle pages which are waste of memory.
Link: http://lkml.kernel.org/r/20181127055429.251614-5-minchan@kernel.org Signed-off-by: Minchan Kim minchan@kernel.org Cc: Joey Pabalinas joeypabalinas@gmail.com Cc: Sergey Senozhatsky sergey.senozhatsky.work@gmail.com Cc: stable@vger.kernel.org [4.14+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
Documentation/ABI/testing/sysfs-block-zram | 8 ++ Documentation/blockdev/zram.txt | 10 ++- drivers/block/zram/zram_drv.c | 57 ++++++++++++++++++- drivers/block/zram/zram_drv.h | 1 4 files changed, 69 insertions(+), 7 deletions(-)
--- a/Documentation/ABI/testing/sysfs-block-zram~zram-introduce-zram_idle-flag +++ a/Documentation/ABI/testing/sysfs-block-zram @@ -98,3 +98,11 @@ Description: The backing_dev file is read-write and set up backing device for zram to write incompressible pages. For using, user should enable CONFIG_ZRAM_WRITEBACK. + +What: /sys/block/zram<id>/idle +Date: November 2018 +Contact: Minchan Kim minchan@kernel.org +Description: + idle file is write-only and mark zram slot as idle. + If system has mounted debugfs, user can see which slots + are idle via /sys/kernel/debug/zram/zram<id>/block_state --- a/Documentation/blockdev/zram.txt~zram-introduce-zram_idle-flag +++ a/Documentation/blockdev/zram.txt @@ -169,6 +169,7 @@ comp_algorithm RW show and change compact WO trigger memory compaction debug_stat RO this file is used for zram debugging purposes backing_dev RW set up backend storage for zram to write out +idle WO mark allocated slot as idle
User space is advised to use the following files to read the device statistics. @@ -251,16 +252,17 @@ pages of the process with*pagemap. If you enable the feature, you could see block state via /sys/kernel/debug/zram/zram0/block_state". The output is as follows,
- 300 75.033841 .wh - 301 63.806904 s.. - 302 63.806919 ..h + 300 75.033841 .wh. + 301 63.806904 s... + 302 63.806919 ..hi
First column is zram's block index. Second column is access time since the system was booted Third column is state of the block. (s: same page w: written page to backing store -h: huge page) +h: huge page +i: idle page)
First line of above example says 300th block is accessed at 75.033841sec and the block's state is huge so it is written back to the backing --- a/drivers/block/zram/zram_drv.c~zram-introduce-zram_idle-flag +++ a/drivers/block/zram/zram_drv.c @@ -281,6 +281,47 @@ static ssize_t mem_used_max_store(struct return len; }
+static ssize_t idle_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + struct zram *zram = dev_to_zram(dev); + unsigned long nr_pages = zram->disksize >> PAGE_SHIFT; + int index; + char mode_buf[8]; + ssize_t sz; + + sz = strscpy(mode_buf, buf, sizeof(mode_buf)); + if (sz <= 0) + return -EINVAL; + + /* ignore trailing new line */ + if (mode_buf[sz - 1] == '\n') + mode_buf[sz - 1] = 0x00; + + if (strcmp(mode_buf, "all")) + return -EINVAL; + + down_read(&zram->init_lock); + if (!init_done(zram)) { + up_read(&zram->init_lock); + return -EINVAL; + } + + for (index = 0; index < nr_pages; index++) { + zram_slot_lock(zram, index); + if (!zram_allocated(zram, index)) + goto next; + + zram_set_flag(zram, index, ZRAM_IDLE); +next: + zram_slot_unlock(zram, index); + } + + up_read(&zram->init_lock); + + return len; +} + #ifdef CONFIG_ZRAM_WRITEBACK static void reset_bdev(struct zram *zram) { @@ -638,6 +679,7 @@ static void zram_debugfs_destroy(void)
static void zram_accessed(struct zram *zram, u32 index) { + zram_clear_flag(zram, index, ZRAM_IDLE); zram->table[index].ac_time = ktime_get_boottime(); }
@@ -670,12 +712,13 @@ static ssize_t read_block_state(struct f
ts = ktime_to_timespec64(zram->table[index].ac_time); copied = snprintf(kbuf + written, count, - "%12zd %12lld.%06lu %c%c%c\n", + "%12zd %12lld.%06lu %c%c%c%c\n", index, (s64)ts.tv_sec, ts.tv_nsec / NSEC_PER_USEC, zram_test_flag(zram, index, ZRAM_SAME) ? 's' : '.', zram_test_flag(zram, index, ZRAM_WB) ? 'w' : '.', - zram_test_flag(zram, index, ZRAM_HUGE) ? 'h' : '.'); + zram_test_flag(zram, index, ZRAM_HUGE) ? 'h' : '.', + zram_test_flag(zram, index, ZRAM_IDLE) ? 'i' : '.');
if (count < copied) { zram_slot_unlock(zram, index); @@ -720,7 +763,10 @@ static void zram_debugfs_unregister(stru #else static void zram_debugfs_create(void) {}; static void zram_debugfs_destroy(void) {}; -static void zram_accessed(struct zram *zram, u32 index) {}; +static void zram_accessed(struct zram *zram, u32 index) +{ + zram_clear_flag(zram, index, ZRAM_IDLE); +}; static void zram_debugfs_register(struct zram *zram) {}; static void zram_debugfs_unregister(struct zram *zram) {}; #endif @@ -924,6 +970,9 @@ static void zram_free_page(struct zram * #ifdef CONFIG_ZRAM_MEMORY_TRACKING zram->table[index].ac_time = 0; #endif + if (zram_test_flag(zram, index, ZRAM_IDLE)) + zram_clear_flag(zram, index, ZRAM_IDLE); + if (zram_test_flag(zram, index, ZRAM_HUGE)) { zram_clear_flag(zram, index, ZRAM_HUGE); atomic64_dec(&zram->stats.huge_pages); @@ -1589,6 +1638,7 @@ static DEVICE_ATTR_RO(initstate); static DEVICE_ATTR_WO(reset); static DEVICE_ATTR_WO(mem_limit); static DEVICE_ATTR_WO(mem_used_max); +static DEVICE_ATTR_WO(idle); static DEVICE_ATTR_RW(max_comp_streams); static DEVICE_ATTR_RW(comp_algorithm); #ifdef CONFIG_ZRAM_WRITEBACK @@ -1602,6 +1652,7 @@ static struct attribute *zram_disk_attrs &dev_attr_compact.attr, &dev_attr_mem_limit.attr, &dev_attr_mem_used_max.attr, + &dev_attr_idle.attr, &dev_attr_max_comp_streams.attr, &dev_attr_comp_algorithm.attr, #ifdef CONFIG_ZRAM_WRITEBACK --- a/drivers/block/zram/zram_drv.h~zram-introduce-zram_idle-flag +++ a/drivers/block/zram/zram_drv.h @@ -48,6 +48,7 @@ enum zram_pageflags { ZRAM_SAME, /* Page consists the same element */ ZRAM_WB, /* page is stored on backing_device */ ZRAM_HUGE, /* Incompressible page */ + ZRAM_IDLE, /* not accessed page since last idle marking */
__NR_ZRAM_PAGEFLAGS, }; _
Patches currently in -mm which might be from minchan@kernel.org are
zram-fix-lockdep-warning-of-free-block-handling.patch zram-fix-double-free-backing-device.patch zram-refactoring-flags-and-writeback-stuff.patch zram-introduce-zram_idle-flag.patch zram-support-idle-huge-page-writeback.patch zram-add-bd_stat-statistics.patch zram-writeback-throttle.patch