From: Greg Edwards <edwardsg@sgi.com>
To: Paul Jackson <pj@sgi.com>
Cc: paulmck@us.ibm.com, akpm@osdl.org, dada1@cosmosbay.com,
linux-kernel@vger.kernel.org, nickpiggin@yahoo.com.au,
Simon.Derr@bull.net, ak@suse.de, clameter@sgi.com
Subject: Re: CONFIG_DEBUG_PREEMPT (was: [PATCH 04/04] Cpuset: skip rcu check ...)
Date: Mon, 19 Dec 2005 10:39:30 -0600 [thread overview]
Message-ID: <20051219163930.GG1320@sgi.com> (raw)
In-Reply-To: <20051219080401.861acca2.pj@sgi.com>
On Mon, Dec 19, 2005 at 08:04:01AM -0800, Paul Jackson wrote:
| Greg - CONFIG_DEBUG_PREEMPT adds a couple of pages of assembly code
| due to various BUG checks beneath rcu_read_lock() on some hot code
| paths (which is where rcu is most popular). See the two calls
| add_preempt_count() and sub_preempt_count() in kernel/sched.c.
|
| Was this intentional to enable CONFIG_DEBUG_PREEMPT in sn2_defconfig?
It wasn't intentional at the time. I believe it was pulled in
automatically when we refreshed since we had CONFIG_PREEMPT on. That
said, it has proven itself useful in turning up some bugs.
Greg
prev parent reply other threads:[~2005-12-19 16:39 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-14 8:40 [PATCH 01/04] Cpuset: remove rcu slab cache optimization Paul Jackson
2005-12-14 8:40 ` [PATCH 02/04] Cpuset: use rcu directly optimization Paul Jackson
2005-12-16 17:55 ` Paul E. McKenney
2005-12-16 20:22 ` Paul Jackson
2005-12-14 8:40 ` [PATCH 03/04] Cpuset: mark number_of_cpusets read_mostly Paul Jackson
2005-12-14 8:40 ` [PATCH 04/04] Cpuset: skip rcu check if task is in root cpuset Paul Jackson
2005-12-16 17:52 ` Paul E. McKenney
2005-12-16 20:06 ` Paul Jackson
2005-12-17 16:47 ` Paul E. McKenney
2005-12-19 14:48 ` Paul Jackson
2005-12-19 16:04 ` CONFIG_DEBUG_PREEMPT (was: [PATCH 04/04] Cpuset: skip rcu check ...) Paul Jackson
2005-12-19 16:39 ` Greg Edwards [this message]
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