Re: [PATCH v4 0/9] epoll: Introduce new syscalls, epoll_ctl_batch and epoll_pwait1

[Paolo Bonzini]

On 13/03/2015 15:46, Jason Baron wrote:
> > The throttling algorithm computes a duration for the next IO, which is used to
> > arm a timer in order to delay the request a bit. As timers are always rounded
> > *UP* to the effective granularity, the timeout being 1ms in epoll_pwait is just
> > too coarse and will lead to severe inaccuracy. With epoll_pwait1, we can avoid
> > the rounding-up.
> 
> right, but we could use the timerfd here to get the desired precision.

Fam, didn't you see slowdowns with few file descriptors
epoll_ctl+epoll_wait+timerfd compared to ppoll?

Do they disappear or improve with epoll_ctl_batch and epoll_pwait1?

Paolo
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