From: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Subject: zram: introduce per-device debug_stat sysfs node debug_stat sysfs is read-only and represents various debugging data that zram developers may need. This file is not meant to be used by anyone else: its content is not documented and will change any time w/o any notice. Therefore, the output of debug_stat file contains a version string. To avoid any confusion, we will increase the version number every time we modify the output. At the moment this file exports only one value -- the number of re-compressions, IOW, the number of times compression fast path has failed. This stat is temporary any will be useful in case if any per-cpu compression streams regressions will be reported. Link: http://lkml.kernel.org/r/20160513230834.GB26763@bbox Link: http://lkml.kernel.org/r/20160511134553.12655-1-sergey.senozhatsky@xxxxxxxxx Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/ABI/testing/sysfs-block-zram | 9 ++++++++ Documentation/blockdev/zram.txt | 1 drivers/block/zram/zram_drv.c | 21 +++++++++++++++++++ drivers/block/zram/zram_drv.h | 1 4 files changed, 32 insertions(+) diff -puN Documentation/ABI/testing/sysfs-block-zram~zram-introduce-per-device-debug_stat-sysfs-node Documentation/ABI/testing/sysfs-block-zram --- a/Documentation/ABI/testing/sysfs-block-zram~zram-introduce-per-device-debug_stat-sysfs-node +++ a/Documentation/ABI/testing/sysfs-block-zram @@ -166,3 +166,12 @@ Description: The mm_stat file is read-only and represents device's mm statistics (orig_data_size, compr_data_size, etc.) in a format similar to block layer statistics file format. + +What: /sys/block/zram<id>/debug_stat +Date: July 2016 +Contact: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> +Description: + The debug_stat file is read-only and represents various + device's debugging info useful for kernel developers. Its + format is not documented intentionally and may change + anytime without any notice. diff -puN Documentation/blockdev/zram.txt~zram-introduce-per-device-debug_stat-sysfs-node Documentation/blockdev/zram.txt --- a/Documentation/blockdev/zram.txt~zram-introduce-per-device-debug_stat-sysfs-node +++ a/Documentation/blockdev/zram.txt @@ -172,6 +172,7 @@ mem_limit RW the maximum amou pages_compacted RO the number of pages freed during compaction (available only via zram<id>/mm_stat node) compact WO trigger memory compaction +debug_stat RO this file is used for zram debugging purposes WARNING ======= diff -puN drivers/block/zram/zram_drv.c~zram-introduce-per-device-debug_stat-sysfs-node drivers/block/zram/zram_drv.c --- a/drivers/block/zram/zram_drv.c~zram-introduce-per-device-debug_stat-sysfs-node +++ a/drivers/block/zram/zram_drv.c @@ -435,8 +435,26 @@ static ssize_t mm_stat_show(struct devic return ret; } +static ssize_t debug_stat_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + int version = 1; + struct zram *zram = dev_to_zram(dev); + ssize_t ret; + + down_read(&zram->init_lock); + ret = scnprintf(buf, PAGE_SIZE, + "version: %d\n%8llu\n", + version, + (u64)atomic64_read(&zram->stats.writestall)); + up_read(&zram->init_lock); + + return ret; +} + static DEVICE_ATTR_RO(io_stat); static DEVICE_ATTR_RO(mm_stat); +static DEVICE_ATTR_RO(debug_stat); ZRAM_ATTR_RO(num_reads); ZRAM_ATTR_RO(num_writes); ZRAM_ATTR_RO(failed_reads); @@ -719,6 +737,8 @@ compress_again: zcomp_strm_release(zram->comp, zstrm); zstrm = NULL; + atomic64_inc(&zram->stats.writestall); + handle = zs_malloc(meta->mem_pool, clen, GFP_NOIO | __GFP_HIGHMEM); if (handle) @@ -1181,6 +1201,7 @@ static struct attribute *zram_disk_attrs &dev_attr_comp_algorithm.attr, &dev_attr_io_stat.attr, &dev_attr_mm_stat.attr, + &dev_attr_debug_stat.attr, NULL, }; diff -puN drivers/block/zram/zram_drv.h~zram-introduce-per-device-debug_stat-sysfs-node drivers/block/zram/zram_drv.h --- a/drivers/block/zram/zram_drv.h~zram-introduce-per-device-debug_stat-sysfs-node +++ a/drivers/block/zram/zram_drv.h @@ -85,6 +85,7 @@ struct zram_stats { atomic64_t zero_pages; /* no. of zero filled pages */ atomic64_t pages_stored; /* no. of pages currently stored */ atomic_long_t max_used_pages; /* no. of maximum pages stored */ + atomic64_t writestall; /* no. of write slow paths */ }; struct zram_meta { _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
