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Date: Thu, 13 Nov 2008 18:34:51 +0100
From: Andi Kleen <andi@firstfloor.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Andi Kleen <andi@firstfloor.org>,
       =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>,
       Ingo Molnar <mingo@elte.hu>,
       Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] tracing/function-return-tracer: Make the function return tracer lockless
Message-ID: <20081113173451.GY3810@one.firstfloor.org>
References: <491B4F0A.3080901@gmail.com> <87od0jd6ds.fsf@basil.nowhere.org> <c62985530811130901t7ddf84beof39a964582fb94a0@mail.gmail.com> <20081113171220.GX3810@one.firstfloor.org> <alpine.DEB.1.10.0811131219250.23751@gandalf.stny.rr.com>
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> So the answer to this is:
> 
>   i = index++;
>   barrier();
>   write to index i (not index);

That was my first thought when I wrote the original email,
but the disadvantage is that barrier() is a big hammer
that flushes everything and can make the code much worse.
That is why I suggested local_add_return() instead.

-Andi

-- 
ak@linux.intel.com