From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>,
hpa@zytor.com, josh@joshtriplett.org, rostedt@goodmis.org,
mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com,
torvalds@linux-foundation.org, mingo@kernel.org,
tglx@linutronix.de, linux-kernel@vger.kernel.org,
oleg@redhat.com, linux-tip-commits@vger.kernel.org
Subject: Re: [tip:sched/core] sched/core: Avoid _cond_resched() for PREEMPT=y
Date: Thu, 22 Sep 2016 13:28:17 -0700 [thread overview]
Message-ID: <20160922202817.GT14933@linux.vnet.ibm.com> (raw)
In-Reply-To: <20160922184228.GA5012@twins.programming.kicks-ass.net>
On Thu, Sep 22, 2016 at 08:42:28PM +0200, Peter Zijlstra wrote:
> On Thu, Sep 22, 2016 at 02:25:01PM -0400, Mikulas Patocka wrote:
> > I've found a document that says that cond_resched() is needed on
> > preemptible kernels to mark RCU quiescent states:
> >
> > https://lwn.net/Articles/603252/
> >
> > Paul, is cond_resched() still needed on current RCU implementation? Or not?
>
> No, we ripped that out. See 4a81e8328d37 ("rcu: Reduce overhead of
> cond_resched() checks for RCU")
I would instead say that we changed the algorithm to reduce the overhead
in the common case, but yes, this commit did change things quite a bit.
Thanx, Paul
next prev parent reply other threads:[~2016-09-22 20:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <tip-35a773a07926a22bf19d77ee00024522279c4e68@git.kernel.org>
2016-09-22 18:25 ` [tip:sched/core] sched/core: Avoid _cond_resched() for PREEMPT=y Mikulas Patocka
2016-09-22 18:30 ` Paul E. McKenney
2016-09-22 18:42 ` Peter Zijlstra
2016-09-22 20:28 ` Paul E. McKenney [this message]
2016-09-23 8:44 ` Peter Zijlstra
2016-09-23 14:47 ` Paul E. McKenney
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