lkml.org 
[lkml]   [2013]   [Sep]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC] eventpoll: Move a kmem_cache_alloc and kmem_cache_free
On 09/18/2013 02:09 PM, Jason Baron wrote:
> On 09/13/2013 11:54 AM, Nathan Zimmer wrote:
>> We noticed some scaling issue in the SPECjbb benchmark. Running perf
>> we found that the it was spending lots of time in SYS_epoll_ctl.
>> In particular it is holding the epmutex.
>> This patch helps by moving out the kmem_cache_alloc and kmem_cache_free out
>> from under the lock. It improves throughput by around 15% on 16 sockets.
>>
>> While this patch should be fine as it is there are probably is more things
>> that can be done out side the lock, like wakeup_source_unregister, but I am
>> not familar with the area and I don't know of many tests. I did find the
>> one posted by Jason Baron at https://lkml.org/lkml/2011/2/25/297.
>>
>> Any thoughts?
>>
> Hi,
>
> Intersting - I think its also possible to completely drop taking the
> 'epmutex' for EPOLL_CTL_DEL by using rcu, and restricting it on add
> to more 'complex' topologies. That is when we have an epoll descriptor
> that doesn't nest with other epoll descriptors, we don't need the
> global 'epmutex' either. Any chance you can re-run with this? Its a bit
> hacky, but we can clean it up if it makes sense.
>
> Thanks,
>
> -Jason
>
That is working GREAT. It is scaling to 16 jobs quite well.
I will have to grab a larger machine( to see what the new scaling curve
will be.


\
 
 \ /
  Last update: 2013-09-19 19:01    [W:0.107 / U:1.036 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site