Messages in this thread | | | Date | Thu, 08 Jan 2015 12:10:51 +0100 | From | Paolo Bonzini <> | Subject | Re: [RESEND PATCH 2/3] epoll: Add implementation for epoll_pwait1 |
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On 08/01/2015 10:16, Fam Zheng wrote: > Unlike ppoll(2), which accepts a timespec argument "timeout_ts" to > specify the timeout, epoll_wait(2) and epoll_pwait(2) expect a > microsecond timeout in int type. > > This is an obstacle for applications in switching from ppoll to epoll, > if they want nanosecond resolution in their event loops. > > Therefore, adding this variation of epoll wait interface, giving user an > option with *both* advantages, is a reasonable move: there could be > constantly scalable performance polling many fds, while having a > nanosecond timeout precision (assuming it has properly set up timer > slack with prctl(2)). > > Signed-off-by: Fam Zheng <famz@redhat.com> > --- > fs/eventpoll.c | 24 ++++++++++++++++++++++++ > include/linux/syscalls.h | 4 ++++ > kernel/sys_ni.c | 3 +++ > 3 files changed, 31 insertions(+)
As mentioned by Miklos in the non-resent version, please add a flags argument. Invalid flags should return -EINVAL.
In fact, we could already use the flags argument to specify an absolute timeout, which is a nice thing to have for QEMU too.
Paolo
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