From: Fam Zheng <famz@redhat.com> To: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org, Alexander Viro <viro@zeniv.linux.org.uk>, Andrew Morton <akpm@linux-foundation.org>, Kees Cook <keescook@chromium.org>, Andy Lutomirski <luto@amacapital.net>, David Herrmann <dh.herrmann@gmail.com>, Alexei Starovoitov <ast@plumgrid.com>, Miklos Szeredi <mszeredi@suse.cz>, David Drysdale <drysdale@google.com>, Oleg Nesterov <oleg@redhat.com>, "David S. Miller" <davem@davemloft.net>, Vivek Goyal <vgoyal@redhat.com>, Mike Frysinger <vapier@gentoo.org>, "Theodore Ts'o" <tytso@mit.edu>, Heiko Carstens <heiko.carstens@de.ibm.com>, Rashika Kheria <rashika.kheria@gmail.com>, Hugh Dickins <hughd@google.com>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, Peter Zijlstra <peterz@infradead.org>, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, Josh Triplett <josh@joshtriplett.org>, "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>, Paolo Bonzini <pbonzini@redhat.com> Subject: Re: [PATCH RFC 0/6] epoll: Introduce new syscall "epoll_mod_wait" Date: Tue, 20 Jan 2015 18:53:38 +0800 [thread overview] Message-ID: <20150120105338.GA4040@ad.nay.redhat.com> (raw) In-Reply-To: <874mrl3fh9.fsf@rasmusvillemoes.dk> On Tue, 01/20 11:37, Rasmus Villemoes wrote: > On Tue, Jan 20 2015, Fam Zheng <famz@redhat.com> wrote: > > > DESCRIPTION > > > > The epoll_mod_wait() system call can be seen as an enhanced combination > > of several epoll_ctl(2) calls, which are followed by an epoll_pwait(2) > > call. It is superior in two cases: > > > > 1) When epoll_ctl(2) are followed by epoll_wait(2), using epoll_mod_wait > > will save context switches between user mode and kernel mode; > > > > 2) When you need higher precision than microsecond for wait timeout. > > You probably want to say millisecond. Yes, you see that I just can't make this right. :) > > > struct epoll_mod_cmd { > [...] > > }; > > > > struct epoll_wait_spec { > [...] > > } EPOLL_PACKED; > > Either both or none of these should mention that EPOLL_PACKED is in fact > part of the actual definition. The changelog for 3/6 sorta mentions > that it's not really needed for epoll_mod_cmd. Why is it necessary for > either struct? Yeah. it's probably not really necessary. > > > RETURN VALUE > > > > When successful, epoll_mod_wait() returns the number of file > > descriptors ready for the requested I/O, or zero if no file descriptor > > became ready during the requested timeout milliseconds. > > And here, it doesn't make sense to mention a unit, since the new timeout > is given using struct timespec (this was the whole point, right?). Right! Thanks, Fam
WARNING: multiple messages have this Message-ID (diff)
From: Fam Zheng <famz-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> To: Rasmus Villemoes <linux-qQsb+v5E8BnlAoU/VqSP6n9LOBIZ5rWg@public.gmane.org> Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>, x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, Alexander Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>, David Herrmann <dh.herrmann-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Alexei Starovoitov <ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>, Miklos Szeredi <mszeredi-AlSwsSmVLrQ@public.gmane.org>, David Drysdale <drysdale-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, "David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>, Vivek Goyal <vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Mike Frysinger <vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org>, "Theodore Ts'o" <tytso-3s7WtUTddSA@public.gmane.org>, Heiko Carstens <heiko.carstens-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>, Rashika Kheria <rashika.kheria-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Mathieu Desnoyers <mathieu.desnoyers-vg+e7yoeK/dWk0Htik3J/w@public.gmane.org>, Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, linux-fsdevel-u79uwXL29TbrhsbdSgBK9A@public.gmane.org Subject: Re: [PATCH RFC 0/6] epoll: Introduce new syscall "epoll_mod_wait" Date: Tue, 20 Jan 2015 18:53:38 +0800 [thread overview] Message-ID: <20150120105338.GA4040@ad.nay.redhat.com> (raw) In-Reply-To: <874mrl3fh9.fsf-qQsb+v5E8BnlAoU/VqSP6n9LOBIZ5rWg@public.gmane.org> On Tue, 01/20 11:37, Rasmus Villemoes wrote: > On Tue, Jan 20 2015, Fam Zheng <famz-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote: > > > DESCRIPTION > > > > The epoll_mod_wait() system call can be seen as an enhanced combination > > of several epoll_ctl(2) calls, which are followed by an epoll_pwait(2) > > call. It is superior in two cases: > > > > 1) When epoll_ctl(2) are followed by epoll_wait(2), using epoll_mod_wait > > will save context switches between user mode and kernel mode; > > > > 2) When you need higher precision than microsecond for wait timeout. > > You probably want to say millisecond. Yes, you see that I just can't make this right. :) > > > struct epoll_mod_cmd { > [...] > > }; > > > > struct epoll_wait_spec { > [...] > > } EPOLL_PACKED; > > Either both or none of these should mention that EPOLL_PACKED is in fact > part of the actual definition. The changelog for 3/6 sorta mentions > that it's not really needed for epoll_mod_cmd. Why is it necessary for > either struct? Yeah. it's probably not really necessary. > > > RETURN VALUE > > > > When successful, epoll_mod_wait() returns the number of file > > descriptors ready for the requested I/O, or zero if no file descriptor > > became ready during the requested timeout milliseconds. > > And here, it doesn't make sense to mention a unit, since the new timeout > is given using struct timespec (this was the whole point, right?). Right! Thanks, Fam
next prev parent reply other threads:[~2015-01-20 10:54 UTC|newest] Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-01-20 9:57 [PATCH RFC 0/6] epoll: Introduce new syscall "epoll_mod_wait" Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 9:57 ` [PATCH RFC 1/6] epoll: Extract epoll_wait_do and epoll_pwait_do Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 9:57 ` [PATCH RFC 2/6] epoll: Specify clockid explicitly Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 9:57 ` [PATCH RFC 3/6] epoll: Add definition for epoll_mod_wait structures Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 9:57 ` [PATCH RFC 4/6] epoll: Extract ep_ctl_do Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 9:57 ` [PATCH RFC 5/6] epoll: Add implementation for epoll_mod_wait Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 12:50 ` Michael Kerrisk (man-pages) 2015-01-20 12:50 ` Michael Kerrisk (man-pages) 2015-01-20 12:50 ` Michael Kerrisk (man-pages) 2015-01-21 4:59 ` Fam Zheng 2015-01-21 4:59 ` Fam Zheng 2015-01-21 4:59 ` Fam Zheng 2015-01-21 7:52 ` Michael Kerrisk (man-pages) 2015-01-21 7:52 ` Michael Kerrisk (man-pages) 2015-01-21 7:52 ` Michael Kerrisk (man-pages) 2015-01-21 8:58 ` Fam Zheng 2015-01-21 8:58 ` Fam Zheng 2015-01-21 10:37 ` Paolo Bonzini 2015-01-21 10:37 ` Paolo Bonzini 2015-01-21 11:14 ` Fam Zheng 2015-01-21 11:14 ` Fam Zheng 2015-01-21 11:14 ` Fam Zheng 2015-01-21 11:50 ` Paolo Bonzini 2015-01-21 11:50 ` Paolo Bonzini 2015-01-21 11:50 ` Paolo Bonzini 2015-01-22 21:12 ` Andy Lutomirski 2015-01-22 21:12 ` Andy Lutomirski 2015-01-22 21:12 ` Andy Lutomirski 2015-01-23 6:20 ` Fam Zheng 2015-01-23 6:20 ` Fam Zheng 2015-01-23 6:20 ` Fam Zheng 2015-01-23 9:56 ` Paolo Bonzini 2015-01-23 9:56 ` Paolo Bonzini 2015-01-23 9:56 ` Paolo Bonzini 2015-01-21 10:34 ` Paolo Bonzini 2015-01-21 10:34 ` Paolo Bonzini 2015-01-21 10:34 ` Paolo Bonzini 2015-01-21 7:56 ` Omar Sandoval 2015-01-21 7:56 ` Omar Sandoval 2015-01-21 7:56 ` Omar Sandoval 2015-01-21 8:59 ` Fam Zheng 2015-01-21 8:59 ` Fam Zheng 2015-01-21 8:59 ` Fam Zheng 2015-01-20 9:57 ` [PATCH RFC 6/6] x86: Hook up epoll_mod_wait syscall Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 9:57 ` Fam Zheng 2015-01-20 10:37 ` [PATCH RFC 0/6] epoll: Introduce new syscall "epoll_mod_wait" Rasmus Villemoes 2015-01-20 10:37 ` Rasmus Villemoes 2015-01-20 10:53 ` Fam Zheng [this message] 2015-01-20 10:53 ` Fam Zheng 2015-01-20 12:48 ` Michael Kerrisk (man-pages) 2015-01-20 12:48 ` Michael Kerrisk (man-pages) 2015-01-20 12:48 ` Michael Kerrisk (man-pages) 2015-01-21 9:05 ` Fam Zheng 2015-01-21 9:05 ` Fam Zheng 2015-01-21 9:05 ` Fam Zheng 2015-01-20 22:40 ` Andy Lutomirski 2015-01-20 22:40 ` Andy Lutomirski 2015-01-20 22:40 ` Andy Lutomirski 2015-01-20 23:03 ` josh 2015-01-20 23:03 ` josh-iaAMLnmF4UmaiuxdJuQwMA 2015-01-20 23:03 ` josh-iaAMLnmF4UmaiuxdJuQwMA 2015-01-21 5:55 ` Michael Kerrisk (man-pages) 2015-01-21 5:55 ` Michael Kerrisk (man-pages) 2015-01-21 5:55 ` Michael Kerrisk (man-pages) 2015-01-21 9:07 ` Fam Zheng 2015-01-21 9:07 ` Fam Zheng 2015-01-21 9:07 ` Fam Zheng
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