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Date: Wed, 22 Jul 2015 06:45:31 +0200
From: Borislav Petkov <bp@alien8.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Michal Marek <mmarek@suse.cz>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Josh Poimboeuf <jpoimboe@redhat.com>,
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        live-patching@vger.kernel.org, X86 ML <x86@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>
Subject: Re: [RFC PATCH 04/21] x86/hweight: Add stack frame dependency for
 __arch_hweight*()
Message-ID: <20150722044531.GC6345@nazgul.tnic>
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On Tue, Jul 21, 2015 at 09:39:23PM -0700, Andy Lutomirski wrote:
> So your shiny perf profile shows cumulative time in whatever called
> them.  Sure, this is arguably silly if we're stuck with frame
> pointers.

You can count 20ish cycles tops for any one of them.

At least that was from the last time when comparing POPCNT perf to the
__sw_hweight* ones. IOW, POPCNT didn't show any improvement vs those sw
versions.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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