From: Roland McGrath <roland@hack.frob.com>
To: Chris Metcalf <cmetcalf@tilera.com>
Cc: Maxim Kuvyrkov <maxim@codesourcery.com>,
Andrew Haley <aph@redhat.com>,
David Miller <davem@davemloft.net>,
<joseph@codesourcery.com>, <rdsandiford@googlemail.com>,
<libc-ports@sourceware.org>, <libc-alpha@sourceware.org>
Subject: Re: [PATCH] Unify pthread_spin_[try]lock implementations.
Date: Wed, 25 Jul 2012 20:43:00 -0000 [thread overview]
Message-ID: <20120725204248.DB82E2C0F1@topped-with-meat.com> (raw)
In-Reply-To: Chris Metcalf's message of Wednesday, 25 July 2012 16:28:44 -0400 <501056FC.80104@tilera.com>
> Some work we did a while back found that bounded exponential delay tended
> to work best for any kind of spinlock. So if we fail to acquire the lock
> the first time around, we wait a few cycles and try again, then keep
> doubling the wait time up to some ceiling (around 1000 cycles or so); see
> ports/sysdeps/tile/nptl/pthread_spin_lock.c.
I see. Some sort of exponential backoff like that is probably a good idea
generally. But in generic code it certainly wouldn't be one that's based
on taking cycle counter samples. It would have to be just counting
iterations of calling atomic_delay.
Thanks,
Roland
next prev parent reply other threads:[~2012-07-25 20:43 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-14 4:36 [PATCH 2/3, MIPS] Rewrite MIPS' pthread_spin_[try]lock using __atomic_* builtins Maxim Kuvyrkov
2012-06-28 23:10 ` Joseph S. Myers
2012-07-11 5:58 ` [PATCH] Unify pthread_spin_[try]lock implementations Maxim Kuvyrkov
2012-07-11 8:15 ` Roland McGrath
2012-07-11 8:25 ` David Miller
2012-07-11 8:44 ` Andrew Haley
2012-07-11 8:54 ` Maxim Kuvyrkov
2012-07-11 9:02 ` Andrew Haley
2012-07-11 9:05 ` Maxim Kuvyrkov
2012-07-11 11:22 ` Roland McGrath
2012-07-11 14:52 ` Chris Metcalf
2012-07-11 22:16 ` Maxim Kuvyrkov
2012-07-25 18:13 ` Roland McGrath
2012-07-25 19:04 ` Chris Metcalf
2012-07-25 20:22 ` Roland McGrath
2012-07-25 20:29 ` Chris Metcalf
2012-07-25 20:43 ` Roland McGrath [this message]
2012-08-15 3:17 ` Maxim Kuvyrkov
2012-08-15 16:27 ` Roland McGrath
2012-08-15 16:39 ` Maxim Kuvyrkov
2012-08-15 16:44 ` Roland McGrath
2012-08-15 16:53 ` Maxim Kuvyrkov
2012-08-15 16:56 ` Roland McGrath
2012-08-15 17:05 ` Maxim Kuvyrkov
2012-08-15 17:05 ` Jeff Law
2012-08-15 17:11 ` Roland McGrath
2012-08-15 17:24 ` Jeff Law
2012-08-15 16:40 ` Joseph S. Myers
2012-08-15 16:43 ` Carlos O'Donell
2012-08-15 22:00 ` Andreas Schwab
2012-08-16 10:21 ` Torvald Riegel
2012-08-16 12:40 ` Chris Metcalf
2012-08-22 23:16 ` Maxim Kuvyrkov
2012-07-11 8:26 ` Maxim Kuvyrkov
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