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Date: Mon, 23 Sep 2002 01:02:46 +0200 (CEST)
From: Ingo Molnar <mingo@elte.hu>
Reply-To: Ingo Molnar <mingo@elte.hu>
To: bob <bob@watson.ibm.com>
Cc: Karim Yaghmour <karim@opersys.com>, <okrieg@us.ibm.com>, <trz@us.ibm.com>,
       linux-kernel <linux-kernel@vger.kernel.org>,
       LTT-Dev <ltt-dev@shafik.org>, Linus Torvalds <torvalds@transmeta.com>
Subject: Re: [ltt-dev] Re: [PATCH] LTT for 2.5.38 1/9: Core infrastructure
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On Sun, 22 Sep 2002, bob wrote:

> [...] On a technical note: a cache-line ping-ponging is bad - a global
> spinlock is horrendous. They're different - the lock-less MP scheme gets
> rid of them both.

(on the contrary - a global spinlock is bad for exactly that reason,
because it causes a cacheline ping-pong. So if two CPUs are trying to
write trace events at once, you'll get the same effect as if they were
using a global spinlock.)

	Ingo

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