* [PATCH] Allow a larger buffer for writes to cpuset files
@ 2006-10-31 2:38 Paul Menage
2006-10-31 4:00 ` Paul Jackson
0 siblings, 1 reply; 3+ messages in thread
From: Paul Menage @ 2006-10-31 2:38 UTC (permalink / raw)
To: Andrew Morton, Paul Jackson; +Cc: linux-kernel
When using fake NUMA setup, the number of memory nodes can greatly
exceed the number of CPUs. So the current limit in
cpuset_common_file_write() is insufficient. PAGE_SIZE is still a bit
of an arbitrary limit, but gives more breathing room.
Signed-off-by: Paul Menage <menage@google.com>
--- 2.6.19-rc2.orig/kernel/cpuset.c
+++ 2.6.19-rc2/kernel/cpuset.c
@@ -1292,7 +1292,7 @@ static ssize_t cpuset_common_file_write(
int retval = 0;
/* Crude upper limit on largest legitimate cpulist user might write. */
- if (nbytes > 100 + 6 * NR_CPUS)
+ if (nbytes >= PAGE_SIZE)
return -E2BIG;
/* +1 for nul-terminator */
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Allow a larger buffer for writes to cpuset files
2006-10-31 2:38 [PATCH] Allow a larger buffer for writes to cpuset files Paul Menage
@ 2006-10-31 4:00 ` Paul Jackson
2006-10-31 4:15 ` Paul Menage
0 siblings, 1 reply; 3+ messages in thread
From: Paul Jackson @ 2006-10-31 4:00 UTC (permalink / raw)
To: Paul Menage; +Cc: akpm, linux-kernel
Paul M wrote:
> @@ -1292,7 +1292,7 @@ static ssize_t cpuset_common_file_write(
> int retval = 0;
>
> /* Crude upper limit on largest legitimate cpulist user might write. */
> - if (nbytes > 100 + 6 * NR_CPUS)
> + if (nbytes >= PAGE_SIZE)
On a system with 4 Kbyte pages, this imposes a tighter limit
if NR_CPUS is > 666.
On a system with 16 Kbyte pages, this imposes a tighter limit
if NR_CPUS is > 2714.
Those CPU counts don't look that futuristic to me.
And it makes the limit more aribitrary ... like what the heck does
that check have to do with PAGE_SIZE ?
How about coding for the possibility that either NR_CPUS or MAX_NUMNODES
is larger, and removing 'cpu' from the comment:
/* Crude upper limit on largest legitimate list user might write. */
if (nbytes > 100 + 6 * max(NR_CPUS, MAX_NUMNODES))
--
I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <pj@sgi.com> 1.925.600.0401
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] Allow a larger buffer for writes to cpuset files
2006-10-31 4:00 ` Paul Jackson
@ 2006-10-31 4:15 ` Paul Menage
0 siblings, 0 replies; 3+ messages in thread
From: Paul Menage @ 2006-10-31 4:15 UTC (permalink / raw)
To: Paul Jackson; +Cc: akpm, linux-kernel
On 10/30/06, Paul Jackson <pj@sgi.com> wrote:
>
> How about coding for the possibility that either NR_CPUS or MAX_NUMNODES
> is larger, and removing 'cpu' from the comment:
>
> /* Crude upper limit on largest legitimate list user might write. */
> if (nbytes > 100 + 6 * max(NR_CPUS, MAX_NUMNODES))
>
Yes, that does seem like a better idea.
Paul
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2006-10-31 4:15 UTC | newest]
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2006-10-31 2:38 [PATCH] Allow a larger buffer for writes to cpuset files Paul Menage
2006-10-31 4:00 ` Paul Jackson
2006-10-31 4:15 ` Paul Menage
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