Re: [PATCH] Documentation: fix wrong value in md.txt

[Jonathan Corbet]

On Fri, 17 Jun 2016 09:40:02 +0800 (CST)
"Tiezhu Yang"  wrote:

> 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.

Applied to the docs tree, thanks.

jon

Re: [PATCH] Documentation: fix wrong value in md.txt

[Jonathan Corbet]

On Fri, 17 Jun 2016 09:40:02 +0800 (CST)
"Tiezhu Yang"  wrote:

> 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.

Applied to the docs tree, thanks.

jon

[PATCH] Documentation: fix wrong value in md.txt

[Tiezhu Yang]

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 
---
 Documentation/md.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/md.txt b/Documentation/md.txt
index 1a2ada4..d6e2fcf 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)
-- 
1.8.3.1

[PATCH] Documentation: fix wrong value in md.txt

[Tiezhu Yang]

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 
---
 Documentation/md.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/md.txt b/Documentation/md.txt
index 1a2ada4..d6e2fcf 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)
-- 
1.8.3.1