On 01/15/2015 06:10 PM, Eric Wong wrote:
> Jason Baron <jbaron@xxxxxxxxxx> wrote:
>> I've done a bit of performance evaluation on a dual socket, 10 core, hyper
>> threading enabled box: Intel(R) Xeon(R) CPU E5-2650 v3 @ 2.30GHz. For the
>> simple epfdN->epfdN->pipefdN topology case where each thread has its
>> own unique files and is doing EPOLL_CTL_ADD and EPOLL_CTL_DEL on the pipefd,
>> I see an almost 300% improvement. This is obviously a very contrived case,
>> but shows the motivation for this patch.
> Any improvements for non-contrived cases? :)
I plan to do some more testing and will post performance findings...
>> +++ b/include/linux/fs.h
>> @@ -835,6 +835,9 @@ struct file {
>> /* Used by fs/eventpoll.c to link all the hooks to this file */
>> struct list_head f_ep_links;
>> struct list_head f_tfile_llink;
>> + /* connected component */
>> + struct list_head f_ep_cc_link;
>> + struct ep_cc __rcu *f_ep_cc;
>> #endif /* #ifdef CONFIG_EPOLL */
> This size increase worries me. Perhaps this can be a separately
> allocated struct to avoid penalizing non-epoll users?
Agreed. That was why I marked this RFC. I was planning to try and shrink
some of the lists to singly-linked lists. But I think breaking it out as 'file_eventpoll'
is a good suggestion. We could simply just always allocate it for an epfd,
and then just allocate it for a 'regular' struct file on the first EPOLL_CTL_ADD.
That would actually result in a net shrinkage of the 'struct file' by 3 pointers from
where we are today. So I think that would be nice.
Thanks,
-Jason
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