lkml.org 
[lkml]   [2010]   [Apr]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: hackbench regression due to commit 9dfc6e68bfe6e
From
Date
On Thu, 2010-04-01 at 10:53 -0500, Christoph Lameter wrote:
> On Thu, 1 Apr 2010, Zhang, Yanmin wrote:
>
> > I suspect the moving of place of cpu_slab in kmem_cache causes the new cache
> > miss. But when I move it to the tail of the structure, kernel always panic when
> > booting. Perhaps there is another potential bug?
>
> Why would that cause an additional cache miss?
>
>
> The node array is following at the end of the structure. If you want to
> move it down then it needs to be placed before the node field

Thanks. The moving cpu_slab to tail doesn't improve it.

I used perf to collect statistics. Only data cache miss has a little difference.
My testing command on my 2 socket machine:
#hackbench 100 process 20000

With 2.6.33, it takes for about 96 seconds while 2.6.34-rc2 (or the latest tip tree)
takes for about 101 seconds.

perf shows some functions around SLUB have more cpu utilization, while some other
SLUB functions have less cpu utilization.




\
 
 \ /
  Last update: 2010-04-02 10:07    [W:0.118 / U:0.308 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site