From: john cooper <john.cooper@third-harmonic.com>
To: "Peter W. Morreale" <pmorreale@novell.com>
Cc: rostedt@goodmis.org, Darren Hart <dvhltc@us.ibm.com>,
"lkml," <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Gregory Haskins <ghaskins@novell.com>,
Sven-Thorsten Dietrich <sdietrich@novell.com>,
Chris Wright <chrisw@sous-sol.org>,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
Eric Dumazet <eric.dumazet@gmail.com>,
john cooper <john.cooper@redhat.com>
Subject: Re: RFC: Ideal Adaptive Spinning Conditions
Date: Sat, 03 Apr 2010 13:51:38 -0400 [thread overview]
Message-ID: <4BB7802A.6020004@third-harmonic.com> (raw)
In-Reply-To: <1270081066.2997.22.camel@hermosa.site>
Peter W. Morreale wrote:
> Right. This was *critical* for the adaptive rtmutex. Note in the RT
> patch, everybody spins as long as the current owner is on CPU.
>
> FWIW, IIRC, Solaris has a heuristic approach where incoming tasks spin
> for a period of time before going to sleep. (Cray UINCOS did the same)
IIRC Solaris mutexes are declared either simple spin or adaptive,
an acquisition attempt of the latter only checking the hold
status of the mutex and if held the owner's run status before
making the spin vs. block decision.
I don't believe mixing of the two mutex types within a given path
was permissible as a previously acquired simple spin mutex could
remain held when a subsequent adaptive mutex decided to block.
Although presumably an elevated IPL could have been sufficient to
flag that scenario.
-john
--
john.cooper@third-harmonic.com
next prev parent reply other threads:[~2010-04-03 18:03 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-31 23:21 RFC: Ideal Adaptive Spinning Conditions Darren Hart
2010-03-31 23:35 ` Roland Dreier
2010-04-01 2:03 ` Darren Hart
2010-04-01 17:02 ` Chris Wright
2010-03-31 23:38 ` Steven Rostedt
2010-04-01 0:17 ` Peter W. Morreale
2010-04-01 2:25 ` Darren Hart
2010-04-03 18:00 ` john cooper
2010-04-05 14:06 ` Darren Hart
2010-04-03 17:51 ` john cooper [this message]
2010-04-01 2:13 ` Darren Hart
2010-04-01 2:25 ` Steven Rostedt
2010-04-01 5:15 ` Darren Hart
2010-04-01 12:46 ` Gregory Haskins
2010-04-04 1:50 ` Rik van Riel
2010-04-04 15:06 ` Peter W. Morreale
2010-04-05 14:10 ` Darren Hart
2010-04-01 2:10 ` Darren Hart
2010-04-01 14:04 ` Chris Mason
2010-04-01 14:20 ` Avi Kivity
2010-04-01 15:54 ` Darren Hart
2010-04-01 16:10 ` Avi Kivity
2010-04-01 17:10 ` Darren Hart
2010-04-01 17:15 ` Avi Kivity
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