lkml.org 
[lkml]   [2010]   [Apr]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: hackbench regression due to commit 9dfc6e68bfe6e
On Tue, 6 Apr 2010, Zhang, Yanmin wrote:

> Thanks. I tried 2 and 4 times and didn't see much improvement.
> I checked /proc/vamallocinfo and it doesn't have item of pcpu_get_vm_areas
> when I use 4 times of PERCPU_DYNAMIC_RESERVE.

> I used perf to collect dtlb misses and LLC misses. dtlb miss data is not
> stable. Sometimes, we have a bigger dtlb miss, but get a better result.
>
> LLC misses data are more stable. Only LLC-load-misses is the clear sign now.
> LLC-store-misses has no big difference.

LLC-load-miss is exactly what condition?

The cacheline environment in the hotpath should only include the following
cache lines (without debugging and counters):

1. The first cacheline from the kmem_cache structure

(This is different from the sitation before the 2.6.34 changes. Earlier
some critical values (object length etc) where available
from the kmem_cache_cpu structure. The cacheline containing the percpu
structure array was needed to determome the kmem_cache_cpu address!)

2. The first cacheline from kmem_cache_cpu

3. The first cacheline of the data object (free pointer)

And in case of a kfree/ kmem_cache_free:

4. Cacheline that contains the page struct of the page the object resides
in.

Can you post the .config you are using and the bootup messages?



\
 
 \ /
  Last update: 2010-04-06 17:45    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site