From: Nathan Zimmer <nzimmer@sgi.com>
To: Jason Baron <jbaron@akamai.com>
Cc: <linux-fsdevel@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [RFC] eventpoll: Move a kmem_cache_alloc and kmem_cache_free
Date: Thu, 19 Sep 2013 11:37:59 -0500 [thread overview]
Message-ID: <523B2867.7000209@sgi.com> (raw)
In-Reply-To: <5239FA69.8030202@akamai.com>
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.
next prev parent reply other threads:[~2013-09-19 16:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-13 15:54 [RFC] eventpoll: Move a kmem_cache_alloc and kmem_cache_free Nathan Zimmer
2013-09-18 19:09 ` Jason Baron
2013-09-19 16:37 ` Nathan Zimmer [this message]
2013-09-23 15:17 ` Jason Baron
2013-09-23 16:47 ` Nathan Zimmer
2013-09-24 19:30 ` Nathan Zimmer
2013-09-22 20:41 ` Eric Wong
2013-09-23 15:45 ` Jason Baron
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=523B2867.7000209@sgi.com \
--to=nzimmer@sgi.com \
--cc=jbaron@akamai.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).