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| author | Tiezhu Yang <kernelpatch@126.com> | 2016-06-17 03:40:02 +0200 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2016-06-23 16:08:36 +0200 |
| commit | a37376f32687cb4043e72f5f761df5cc52e08073 (patch) | |
| tree | fa2779cb363661a8ee5add61862dd98539396d0a /Documentation/md.txt | |
| parent | bcache: documentation formatting, edited for clarity, stripe alignment notes (diff) | |
| download | linux-a37376f32687cb4043e72f5f761df5cc52e08073.tar.xz linux-a37376f32687cb4043e72f5f761df5cc52e08073.zip | |
Documentation: fix wrong value in md.txt
In the current Documentation/md.txt, the lower limit value of
stripe_cache_size is 16 and the default value is 128, but when
I update kernel to the latest mainline version and RAID5 array
is created by mdadm, then execute the following commands, it
shows an error and a difference respectively.
1) set stripe_cache_size to 16
[root@localhost ~]# echo 16 > /sys/block/md0/md/stripe_cache_size
bash: echo: write error: Invalid argument
2) read the default value of stripe_cache_size
[root@localhost ~]# cat /sys/block/md0/md/stripe_cache_size
256
I read drivers/md/raid5.c and find the following related code:
1) in function 'raid5_set_cache_size':
if (size <= 16 || size > 32768)
return -EINVAL;
2) #define NR_STRIPES 256
So the lower limit value of stripe_cache_size should be 17 and
the default value should be 256.
Signed-off-by: Tiezhu Yang <kernelpatch@126.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/md.txt')
| -rw-r--r-- | Documentation/md.txt | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/Documentation/md.txt b/Documentation/md.txt index 1a2ada46aaed..d6e2fcf27337 100644 --- a/Documentation/md.txt +++ b/Documentation/md.txt @@ -602,7 +602,7 @@ These currently include stripe_cache_size (currently raid5 only) number of entries in the stripe cache. This is writable, but - there are upper and lower limits (32768, 16). Default is 128. + there are upper and lower limits (32768, 17). Default is 256. strip_cache_active (currently raid5 only) number of active entries in the stripe cache preread_bypass_threshold (currently raid5 only) |