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Date: Mon, 28 Sep 2015 13:24:01 -0700
From: Davidlohr Bueso <dave@stgolabs.net>
To: Denys Vlasenko <dvlasenk@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>,
        Andy Lutomirski <luto@amacapital.net>, Borislav Petkov <bp@alien8.de>,
        Brian Gerst <brgerst@gmail.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/signal: Deinline get_sigframe, save 240 bytes
Message-ID: <20150928202401.GB4035@linux-uzut.site>
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On Mon, 28 Sep 2015, Denys Vlasenko wrote:

>On 09/28/2015 02:33 PM, H. Peter Anvin wrote:
>> This one makes me slightly nervous, because it isn't clear
>> that these aren't potentially performance sensitive.
>
>CALL instruction is not a crime :)
>It costs about the same as one read-modify-write
>operation on a memory operand.
>
>This function is used in signal delivery code.
>If performance critical code uses massive numbers
>of signals, it already has a problem, Unix signals
>are too inefficient. That's why we have futexes etc...

True, but in general I don't think that justifies anything -- and not only
referring to this particular signal patch.

Nothing really against or in favor of these patches, but I don't think that
saving 240 bytes (or whatever) is worth such changes, in fact we have Josh's
tinyfication project for those systems that do in fact care.

Thanks,
Davidlohr