Messages in this thread | | | Date | Wed, 26 Jan 2011 07:52:23 -0800 (PST) | From | Davide Libenzi <> | Subject | Re: sys_epoll_wait high CPU load in 2.6.37 |
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On Wed, 26 Jan 2011, Eric Dumazet wrote:
> Le mercredi 26 janvier 2011 à 07:31 -0800, Davide Libenzi a écrit : > > On Wed, 26 Jan 2011, Eric Dumazet wrote: > > > > > > diff --git a/fs/eventpoll.c b/fs/eventpoll.c > > > index cc8a9b7..7ec0890 100644 > > > --- a/fs/eventpoll.c > > > +++ b/fs/eventpoll.c > > > @@ -1126,7 +1126,9 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, > > > > > > if (timeout > 0) { > > > ktime_get_ts(&end_time); > > > - timespec_add_ns(&end_time, (u64)timeout * NSEC_PER_MSEC); > > > + end_time.tv_sec += timeout / MSEC_PER_SEC; > > > + timeout %= MSEC_PER_SEC; > > > + timespec_add_ns(&end_time, timeout * NSEC_PER_MSEC); > > > slack = select_estimate_accuracy(&end_time); > > > to = &expires; > > > *to = timespec_to_ktime(end_time); > > > > Yep, we can overflow the timeout, with the calculation above. > > A timespec_add_ms()? > > Well, given timeout after modulo contains a number between 0 and 999, > multiply by 1.000.000 (NSEC_PER_MSEC) cant overflow.
For "above", I meant the current epoll expire time calculation, which was described above in the message ;) The hint for a timespec_add_ms() was because we must be doing something similar in poll, don't we (/me got no code in front ATM)?
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