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Re: [PATCH 1/3] signal: avoid useless test in do_signal()

To: "Ralf Baechle" <ralf@linux-mips.org>
Subject: Re: [PATCH 1/3] signal: avoid useless test in do_signal()
From: "Franck Bui-Huu" <vagabon.xyz@gmail.com>
Date: Fri, 9 Feb 2007 17:50:36 +0100
Cc: linux-mips@linux-mips.org, anemo@mba.ocn.ne.jp, "Franck Bui-Huu" <fbuihuu@gmail.com>
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On 2/9/07, Ralf Baechle <ralf@linux-mips.org> wrote:
Ralf Baechle wrote:
On Fri, Feb 09, 2007 at 04:07:36PM +0100, Franck Bui-Huu wrote:

-                       if (test_thread_flag(TIF_RESTORE_SIGMASK))
-                               clear_thread_flag(TIF_RESTORE_SIGMASK);

This is a microoptimization.  The assumption here is TIF_RESTORE_SIGMASK
will rarely need to be cleared and atomic operations are somewhat
expensive if as in this case we have to assume the cacheline isn't
held exclusive yet.


I missed that. You can forget this patch or maybe something like this
is more appropriate ?

        if (unlikely(test_thread_flag(TIF_RESTORE_SIGMASK)))
                clear_thread_flag(TIF_RESTORE_SIGMASK);
--
              Franck

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