From: Ingo Molnar <mingo@elte.hu>
To: Mandeep Singh Baines <msb@google.com>
Cc: linux-kernel@vger.kernel.org,
"Peter Zijlstra" <peterz@infradead.org>,
"Frédéric Weisbecker" <fweisbec@gmail.com>,
rientjes@google.com, mbligh@google.com, thockin@google.com,
"Andrew Morton" <akpm@linux-foundation.org>
Subject: Re: [PATCH v4] softlockup: remove hung_task_check_count
Date: Tue, 27 Jan 2009 14:26:26 +0100 [thread overview]
Message-ID: <20090127132626.GH23121@elte.hu> (raw)
In-Reply-To: <20090127003055.GA21269@google.com>
* Mandeep Singh Baines <msb@google.com> wrote:
> The design was proposed by Frédéric Weisbecker. Peter Zijlstra suggested
> the use of RCU.
ok, this looks _much_ cleaner.
One question:
> - read_lock(&tasklist_lock);
> + rcu_read_lock();
> do_each_thread(g, t) {
> - if (!--max_count)
> + if (need_resched())
> goto unlock;
Isnt it dangerous to skip a check just because we got marked for
reschedule? Since it runs so rarely it could by accident be preempted and
we'd not get any checking done for a long time.
Ingo
next prev parent reply other threads:[~2009-01-27 13:26 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-25 20:50 [RFC][PATCH 2/2] add a counter for writers spinning on a rwlock Frederic Weisbecker
2009-01-26 13:32 ` Ingo Molnar
2009-01-26 13:48 ` Peter Zijlstra
2009-01-26 15:25 ` Frédéric Weisbecker
2009-01-26 15:37 ` Peter Zijlstra
2009-01-26 16:04 ` Frédéric Weisbecker
2009-01-26 17:36 ` Mandeep Baines
2009-01-26 17:41 ` Peter Zijlstra
2009-01-27 0:30 ` [PATCH v4] softlockup: remove hung_task_check_count Mandeep Singh Baines
2009-01-27 9:27 ` Frederic Weisbecker
2009-01-27 13:26 ` Ingo Molnar [this message]
2009-01-27 18:48 ` Mandeep Singh Baines
2009-01-28 8:25 ` Peter Zijlstra
2009-01-29 1:42 ` Mandeep Singh Baines
2009-01-30 20:41 ` Mandeep Singh Baines
2009-01-30 20:46 ` [PATCH 1/2] softlockup: convert read_lock in hung_task to rcu_read_lock Mandeep Singh Baines
2009-01-30 20:49 ` [PATCH 2/2] softlockup: check all tasks in hung_task Mandeep Singh Baines
2009-01-31 19:22 ` Peter Zijlstra
2009-02-03 0:05 ` [PATCH 2/2 v2] " Mandeep Singh Baines
2009-02-03 12:23 ` Ingo Molnar
2009-02-03 20:56 ` [PATCH 2/2 v3] " Mandeep Singh Baines
2009-02-04 19:43 ` Ingo Molnar
2009-02-05 4:35 ` [PATCH 2/2 v4] " Mandeep Singh Baines
2009-02-05 14:34 ` Ingo Molnar
2009-02-05 17:48 ` Andrew Morton
2009-02-05 18:07 ` Ingo Molnar
2009-02-05 18:30 ` Andrew Morton
2009-02-05 18:58 ` Ingo Molnar
2009-02-05 18:40 ` Mandeep Singh Baines
2009-02-05 17:56 ` [PATCH] softlockup: convert read_lock in hung_task to rcu_read_lock Mandeep Singh Baines
2009-02-05 18:13 ` Ingo Molnar
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