From: Andi Kleen <andi@firstfloor.org>
To: Nikanth Karthikesan <knikanth@suse.de>
Cc: Ingo Molnar <mingo@redhat.com>, Nick Piggin <npiggin@kernel.dk>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Andrew Morton <akpm@linux-foundation.org>,
Jan Beulich <JBeulich@novell.com>, Jack Steiner <steiner@sgi.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] x86: avoid atomic operation in test_and_set_bit_lock if possible
Date: Thu, 24 Mar 2011 11:38:28 -0700 [thread overview]
Message-ID: <m2tyestlcr.fsf@firstfloor.org> (raw)
In-Reply-To: <201103241026.01624.knikanth@suse.de> (Nikanth Karthikesan's message of "Thu, 24 Mar 2011 10:26:01 +0530")
Nikanth Karthikesan <knikanth@suse.de> writes:
> On x86_64 SMP with lots of CPU atomic instructions which assert the LOCK #
> signal can stall other CPUs. And as the number of cores increase this penalty
This description is very wrong. No modern CPU still has a LOCK # signal
or does global stalls for LOCK.
Do you actually have any data this is a problem and how much
difference the patch makes?
Also there's the missing barrier now of course.
-Andi
--
ak@linux.intel.com -- Speaking for myself only
prev parent reply other threads:[~2011-03-24 18:39 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-24 4:56 [PATCH RFC] x86: avoid atomic operation in test_and_set_bit_lock if possible Nikanth Karthikesan
2011-03-24 8:52 ` Jan Beulich
2011-03-24 8:56 ` Ingo Molnar
2011-03-24 14:52 ` Borislav Petkov
2011-03-24 16:48 ` Jan Beulich
2011-03-24 17:19 ` Ingo Molnar
2011-03-25 10:06 ` Jan Beulich
2011-03-25 11:10 ` Ingo Molnar
2011-03-25 12:04 ` Nikanth Karthikesan
2011-03-25 13:12 ` Jack Steiner
2011-03-25 16:29 ` Linus Torvalds
2011-03-25 16:47 ` Jan Beulich
2011-03-25 16:49 ` Jack Steiner
2011-03-24 17:30 ` Jack Steiner
2011-03-24 20:00 ` Ingo Molnar
2011-03-24 20:40 ` Andi Kleen
2011-03-24 20:50 ` Ingo Molnar
2011-03-24 21:37 ` Andi Kleen
2011-03-24 20:48 ` Eric Dumazet
2011-03-24 20:54 ` Ingo Molnar
2011-03-24 21:02 ` Eric Dumazet
2011-03-24 21:42 ` Andi Kleen
2011-03-24 23:26 ` Linus Torvalds
2011-03-24 23:56 ` Andi Kleen
2011-03-25 5:47 ` Eric Dumazet
2011-03-25 9:32 ` Ingo Molnar
2011-03-25 9:44 ` Eric Dumazet
2011-03-25 9:59 ` Ingo Molnar
2011-03-25 10:50 ` Borislav Petkov
2011-03-25 11:10 ` Peter Zijlstra
2011-03-25 11:11 ` Ingo Molnar
2011-03-25 16:16 ` Robert Richter
2011-03-25 17:22 ` Andi Kleen
2011-03-25 19:26 ` Ingo Molnar
2011-03-25 9:38 ` Eric Dumazet
2011-03-25 20:29 ` Peter Zijlstra
2011-03-26 8:15 ` Eric Dumazet
2011-03-26 9:44 ` Peter Zijlstra
2011-03-26 9:57 ` Ingo Molnar
2011-03-25 9:22 ` Ingo Molnar
2011-03-25 10:21 ` Peter Zijlstra
2011-03-25 16:08 ` Robert Richter
2011-03-25 19:31 ` Ingo Molnar
2011-03-25 17:15 ` Andi Kleen
2011-03-25 19:21 ` Ingo Molnar
2011-03-25 9:35 ` Ingo Molnar
2011-03-24 17:01 ` Linus Torvalds
2011-03-24 17:13 ` Jack Steiner
2011-03-24 18:38 ` Andi Kleen [this message]
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