Re: [PATCH RFC 5/6] epoll: Add implementation for epoll_mod_wait

[Paolo Bonzini]

On 21/01/2015 12:14, Fam Zheng wrote:
> > My take for simplicity will be leaving epoll_ctl as-is, and my take for
> > performance will be epoll_pwait1. And I don't really like putting my time on
> > epoll_ctl_batch, thinking it as a ambivalent compromise in between.
> 
> > I agree with Michael actually.  The big change is going from O(n)
> > epoll_ctl calls to O(1), and epoll_ctl_batch achieves that just fine.
> > Changing 2 syscalls to 1 is the icing on the cake, but we're talking of
> > a fraction of a microsecond.
> 
> Maybe I'm missing something, but in common cases, the set of fds for epoll_wait
> doesn't change that radically from one iteration to another, does it?

That depends on the application.

Paolo
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