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From: Paolo Bonzini <pbonzini-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Fam Zheng <famz-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: "Michael Kerrisk (man-pages)"
	<mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>,
	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>,
	David Herrmann
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	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>,
	Rasmus Villemoes
	<linux-qQsb+v5E8BnlAoU/VqSP6n9LOBIZ5rWg@public.gmane.org>,
	Rashika Kheria
	<rashika.kheria-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Mathieu
Subject: Re: [PATCH RFC 5/6] epoll: Add implementation for epoll_mod_wait
Date: Wed, 21 Jan 2015 12:50:44 +0100	[thread overview]
Message-ID: <54BF9294.3070902@redhat.com> (raw)
In-Reply-To: <20150121111404.GA3804-ZfWej9ACyHUXGNroddHbYwC/G2K4zDHf@public.gmane.org>



On 21/01/2015 12:14, Fam Zheng wrote:
> > My take for simplicity will be leaving epoll_ctl as-is, and my take for
> > performance will be epoll_pwait1. And I don't really like putting my time on
> > epoll_ctl_batch, thinking it as a ambivalent compromise in between.
> 
> > I agree with Michael actually.  The big change is going from O(n)
> > epoll_ctl calls to O(1), and epoll_ctl_batch achieves that just fine.
> > Changing 2 syscalls to 1 is the icing on the cake, but we're talking of
> > a fraction of a microsecond.
> 
> Maybe I'm missing something, but in common cases, the set of fds for epoll_wait
> doesn't change that radically from one iteration to another, does it?

That depends on the application.

Paolo

  parent reply	other threads:[~2015-01-21 11:50 UTC|newest]

Thread overview: 28+ 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 ` [PATCH RFC 1/6] epoll: Extract epoll_wait_do and epoll_pwait_do Fam Zheng
2015-01-20  9:57 ` [PATCH RFC 2/6] epoll: Specify clockid explicitly 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 ` [PATCH RFC 4/6] epoll: Extract ep_ctl_do Fam Zheng
2015-01-20  9:57 ` [PATCH RFC 5/6] epoll: Add implementation for epoll_mod_wait Fam Zheng
2015-01-20 12:50   ` Michael Kerrisk (man-pages)
2015-01-21  4:59     ` Fam Zheng
     [not found]       ` <20150121045903.GA2858-+wGkCoP0yD+sDdueE5tM26fLeoKvNuZc@public.gmane.org>
2015-01-21  7:52         ` Michael Kerrisk (man-pages)
2015-01-21  8:58           ` Fam Zheng
     [not found]             ` <20150121085827.GB23024-ZfWej9ACyHUXGNroddHbYwC/G2K4zDHf@public.gmane.org>
2015-01-21 10:37               ` Paolo Bonzini
2015-01-21 11:14                 ` Fam Zheng
     [not found]                   ` <20150121111404.GA3804-ZfWej9ACyHUXGNroddHbYwC/G2K4zDHf@public.gmane.org>
2015-01-21 11:50                     ` Paolo Bonzini [this message]
2015-01-22 21:12                       ` Andy Lutomirski
     [not found]                         ` <CALCETrWwuJpFK+38mBxxTQCu7Oig22Nr+mAuO++Y+0CdAhfzkw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-01-23  6:20                           ` Fam Zheng
2015-01-23  9:56                           ` Paolo Bonzini
2015-01-21 10:34           ` Paolo Bonzini
     [not found]   ` <1421747878-30744-6-git-send-email-famz-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2015-01-21  7:56     ` Omar Sandoval
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
     [not found] ` <1421747878-30744-1-git-send-email-famz-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2015-01-20 10:37   ` [PATCH RFC 0/6] epoll: Introduce new syscall "epoll_mod_wait" Rasmus Villemoes
     [not found]     ` <874mrl3fh9.fsf-qQsb+v5E8BnlAoU/VqSP6n9LOBIZ5rWg@public.gmane.org>
2015-01-20 10:53       ` Fam Zheng
2015-01-20 12:48   ` Michael Kerrisk (man-pages)
     [not found]     ` <54BE4EA4.6080901-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-01-21  9:05       ` Fam Zheng
2015-01-20 22:40   ` Andy Lutomirski
     [not found]     ` <CALCETrU4TeG1ShVLkQgqQ6usFm8pg_t0D8K=Mi_UJGSfxUwXtA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-01-20 23:03       ` josh-iaAMLnmF4UmaiuxdJuQwMA
2015-01-21  5:55       ` Michael Kerrisk (man-pages)
2015-01-21  9:07       ` Fam Zheng

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