From: Andrew Morton <akpm@osdl.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: ccb@acm.org, linux-kernel@vger.kernel.org
Subject: Re: [patch] increase spinlock-debug looping timeouts from 1 sec to 1 min
Date: Mon, 19 Jun 2006 00:59:55 -0700 [thread overview]
Message-ID: <20060619005955.b05840e8.akpm@osdl.org> (raw)
In-Reply-To: <20060619070229.GA8293@elte.hu>
On Mon, 19 Jun 2006 09:02:29 +0200
Ingo Molnar <mingo@elte.hu> wrote:
> Subject: increase spinlock-debug looping timeouts from 1 sec to 1 min
But it's broken. In the non-debug case we subtract RW_LOCK_BIAS so we know
that the writer will get the lock when all readers vacate. But in the
CONFIG_DEBUG_SPINLOCK case we don't do that, with the result that taking a
write_lock can take over a second.
A much, much better fix (which involves visiting all architectures) would
be to subtract RW_LOCK_BIAS and _then_ wait for a second.
OK, it's only debug code. But RH (for one) have decided to ship zillions
of kernels with this debug code turned on.
next prev parent reply other threads:[~2006-06-19 8:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-12 19:53 BUG: write-lock lockup Charles C. Bennett, Jr.
2006-06-17 17:07 ` Andrew Morton
2006-06-19 7:02 ` [patch] increase spinlock-debug looping timeouts from 1 sec to 1 min Ingo Molnar
2006-06-19 7:59 ` Andrew Morton [this message]
2006-06-19 8:12 ` Ingo Molnar
2006-06-19 8:21 ` Ingo Molnar
2006-06-19 8:32 ` Andrew Morton
2006-06-19 8:35 ` Ingo Molnar
2006-06-19 9:13 ` Andrew Morton
2006-06-19 11:39 ` Ingo Molnar
2006-06-19 19:55 ` Andrew Morton
2006-06-20 8:06 ` Arjan van de Ven
2006-06-20 8:40 ` [patch] fix spinlock-debug looping Ingo Molnar
2006-06-20 8:52 ` Andrew Morton
2006-06-20 9:15 ` Ingo Molnar
2006-06-20 9:32 ` Andrew Morton
2006-06-20 9:34 ` Ingo Molnar
2006-06-20 16:02 ` Dave Olson
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