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Message-ID: <20160513230834.GB26763@bbox>
Date: Sat, 14 May 2016 08:08:34 +0900
From: Minchan Kim <minchan@...nel.org>
To: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
CC: Andrew Morton <akpm@...ux-foundation.org>,
<linux-kernel@...r.kernel.org>,
Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: Re: [PATCH] zram: introduce per-device debug_stat sysfs node
On Fri, May 13, 2016 at 10:03:58PM +0900, Sergey Senozhatsky wrote:
> 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.
>
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> Acked-by: Minchan Kim <minchan@...nel.org>
Fortunately, Andrew isn't pick up this patch yet so I want to replace
it to below suggested by Sergey which is better.
>From ba2f6c37ceeb11c6afc0f078ccc2ed0ead5e1104 Mon Sep 17 00:00:00 2001
From: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Date: Sat, 14 May 2016 07:55:31 +0900
Subject: [PATCH] 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.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Signed-off-by: Minchan Kim <minchan@...nel.org>
---
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 --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram
index 2e69e83bf510..4518d30b8c2e 100644
--- a/Documentation/ABI/testing/sysfs-block-zram
+++ b/Documentation/ABI/testing/sysfs-block-zram
@@ -166,3 +166,12 @@ Contact: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
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@...il.com>
+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 --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index d88f0c70cd7f..13100fb3c26d 100644
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -172,6 +172,7 @@ mem_limit RW the maximum amount of memory ZRAM can use to store
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 --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 8fcfbebe79cd..8fcad8b761f1 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -435,8 +435,26 @@ static ssize_t mm_stat_show(struct device *dev,
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 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
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 --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 06b1636f4722..3f5bf66a27e4 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/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 {
--
1.9.1
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