From: Linus Torvalds <torvalds@linux-foundation.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Nikita V. Youshchenko" <nyoushchenko@mvista.com>,
Matt Fleming <matt@console-pimps.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] signal: sys_rt_sigtimedwait: simplify the timeout logic
Date: Mon, 25 Apr 2011 10:34:30 -0700 [thread overview]
Message-ID: <BANLkTinrC1+5CVgnBCxrt895TAnLCKjTRg@mail.gmail.com> (raw)
In-Reply-To: <20110425172644.GA20689@redhat.com>
On Mon, Apr 25, 2011 at 10:26 AM, Oleg Nesterov <oleg@redhat.com> wrote:
>
> If only I knew what this comment could say except
>
> /* Why do we add (tv_sec || tv_nsec) ? */
>
> I'd better send 4/3 which simply removes this (I hope) unneeded code.
It's to guarantee that timeout is at least one tick more than asked
for, because the rule is that you really have to wait for AT LEAST the
time asked for. With the "zero timeout" being special, since that is
"immediate".
Imagine that you ask for one timer tick - but that you're in the
_middle_ of the current one. Waiting for the next timer is going to be
too short - you'll only get half a timer tick. So we need to ask for
"ceiling(nanoseconds / nanosecondspertick) + 1" to make sure that we
really wait _longer_ than asked for.
So "+ (tv_sec || tv_nsec)" is just the "+1" for the "not zero timeout" case.
Linus
next prev parent reply other threads:[~2011-04-25 17:35 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-18 13:44 [RFC PATCH v2 0/7] signal: sigprocmask fixes Oleg Nesterov
2011-04-18 13:44 ` [PATCH v2 1/7] signal: introduce retarget_shared_pending() Oleg Nesterov
2011-04-22 12:04 ` Matt Fleming
2011-04-25 10:49 ` Tejun Heo
2011-04-18 13:45 ` [PATCH v2 2/7] signal: retarget_shared_pending: consider shared/unblocked signals only Oleg Nesterov
2011-04-22 12:22 ` Matt Fleming
2011-04-25 10:52 ` Tejun Heo
2011-04-25 15:20 ` Oleg Nesterov
2011-04-25 16:19 ` Tejun Heo
2011-04-25 17:02 ` Oleg Nesterov
2011-04-25 17:11 ` Tejun Heo
2011-04-26 19:45 ` Oleg Nesterov
2011-04-28 15:26 ` [PATCHSET] signals-review branch Oleg Nesterov
2011-04-30 12:51 ` Tejun Heo
2011-04-18 13:45 ` [PATCH v2 3/7] signal: retarget_shared_pending: optimize while_each_thread() loop Oleg Nesterov
2011-04-22 12:26 ` Matt Fleming
2011-04-25 11:03 ` Tejun Heo
2011-04-18 13:45 ` [PATCH v2 4/7] signal: sigprocmask: narrow the scope of ->siglock Oleg Nesterov
2011-04-22 12:31 ` Matt Fleming
2011-04-25 11:05 ` Tejun Heo
2011-04-18 13:45 ` [PATCH v2 5/7] signal: sigprocmask() should do retarget_shared_pending() Oleg Nesterov
2011-04-22 12:46 ` Matt Fleming
2011-04-25 11:14 ` Tejun Heo
2011-04-18 13:46 ` [PATCH v2 6/7] x86: signal: handle_signal() should use set_current_blocked() Oleg Nesterov
2011-04-22 13:45 ` Matt Fleming
2011-04-25 11:19 ` Tejun Heo
2011-04-18 13:46 ` [PATCH v2 7/7] x86: signal: sys_rt_sigreturn() " Oleg Nesterov
2011-04-22 14:14 ` Matt Fleming
2011-04-23 18:12 ` Oleg Nesterov
2011-04-25 11:21 ` Tejun Heo
2011-04-18 13:47 ` [PATCH v2 8/7] signal: cleanup sys_rt_sigprocmask() Oleg Nesterov
2011-04-22 14:30 ` Matt Fleming
2011-04-23 18:20 ` Oleg Nesterov
2011-04-23 18:47 ` Matt Fleming
2011-04-25 11:26 ` Tejun Heo
2011-04-18 17:16 ` [RFC PATCH v2 0/7] signal: sigprocmask fixes Linus Torvalds
2011-04-18 17:32 ` Oleg Nesterov
2011-04-18 17:40 ` Linus Torvalds
2011-04-23 17:59 ` [PATCH 0/3] do_sigtimedwait() needs retarget_shared_pending() Oleg Nesterov
2011-04-23 17:59 ` [PATCH 1/3] signal: sys_rt_sigtimedwait: simplify the timeout logic Oleg Nesterov
2011-04-25 11:37 ` Tejun Heo
2011-04-25 17:26 ` Oleg Nesterov
2011-04-25 17:34 ` Linus Torvalds [this message]
2011-04-25 17:56 ` Oleg Nesterov
2011-04-25 19:38 ` Linus Torvalds
2011-04-26 10:18 ` Matt Fleming
2011-04-23 17:59 ` [PATCH 2/3] signal: introduce do_sigtimedwait() to factor out compat/native code Oleg Nesterov
2011-04-25 11:39 ` Tejun Heo
2011-04-25 11:49 ` Tejun Heo
2011-04-25 15:33 ` Oleg Nesterov
2011-04-25 16:25 ` Tejun Heo
2011-04-26 10:28 ` Matt Fleming
2011-04-23 18:00 ` [PATCH 3/3] signal: do_sigtimedwait() needs retarget_shared_pending() Oleg Nesterov
2011-04-25 11:52 ` Tejun Heo
2011-04-25 16:01 ` Oleg Nesterov
2011-04-25 16:27 ` Tejun Heo
2011-04-25 17:07 ` Oleg Nesterov
2011-04-25 17:12 ` Tejun Heo
2011-04-26 10:40 ` Matt Fleming
2011-04-26 10:42 ` Matt Fleming
2011-04-26 19:48 ` [PATCH v2 0/6] sigtimedwait/sigprocmask need retarget_shared_pending() Oleg Nesterov
2011-04-26 19:48 ` [PATCH v2 1/6] signal: sys_rt_sigtimedwait: simplify the timeout logic Oleg Nesterov
2011-04-26 19:49 ` [PATCH v2 2/6] signal: introduce do_sigtimedwait() to factor out compat/native code Oleg Nesterov
2011-04-27 10:09 ` Tejun Heo
2011-04-27 21:24 ` Matt Fleming
2011-05-11 16:21 ` Mike Frysinger
2011-05-12 18:54 ` Oleg Nesterov
2011-05-13 16:44 ` [PATCH] signal: trivial, fix the "timespec declared inside parameter list" warning Oleg Nesterov
2011-05-13 18:09 ` Mike Frysinger
2011-05-16 12:57 ` Oleg Nesterov
2011-05-16 12:57 ` [PATCH v2] " Oleg Nesterov
2011-05-16 17:39 ` Mike Frysinger
2011-05-18 23:37 ` Andrew Morton
2011-05-19 18:19 ` Oleg Nesterov
2011-05-19 19:21 ` Mike Frysinger
2011-04-26 19:49 ` [PATCH v2 3/6] signal: do_sigtimedwait() needs retarget_shared_pending() Oleg Nesterov
2011-04-26 19:49 ` [PATCH v2 4/6] signal: cleanup sys_sigprocmask() Oleg Nesterov
2011-04-27 10:12 ` Tejun Heo
2011-04-27 21:31 ` Matt Fleming
2011-04-26 19:50 ` [PATCH v2 5/6] signal: sys_sigprocmask() needs retarget_shared_pending() Oleg Nesterov
2011-04-26 21:43 ` Linus Torvalds
2011-04-27 12:57 ` Oleg Nesterov
2011-04-27 13:04 ` Tejun Heo
2011-05-01 20:07 ` [PATCH v2 0/1] " Oleg Nesterov
2011-05-01 20:08 ` [PATCH v2 1/1] " Oleg Nesterov
2011-04-26 19:50 ` [PATCH v2 6/6] signal: rename signandsets() to sigandnsets() Oleg Nesterov
2011-04-27 10:11 ` Tejun Heo
2011-04-27 21:43 ` Matt Fleming
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