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

On 13/03/2015 15:46, Jason Baron wrote:

quoted

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