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Date: Fri, 01 Aug 2014 15:13:19 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Denys Vlasenko <vda.linux@googlemail.com>
CC: Denys Vlasenko <dvlasenk@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Oleg Nesterov <oleg@redhat.com>, Andy Lutomirski <luto@amacapital.net>,
        Frederic Weisbecker <fweisbec@gmail.com>, X86 ML <x86@kernel.org>,
        Alexei Starovoitov <ast@plumgrid.com>, Will Drewry <wad@chromium.org>,
        Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH 4/5] x86: entry_64.S: always allocate complete "struct
 pt_regs"
References: <1406904498-21647-1-git-send-email-dvlasenk@redhat.com> <1406904498-21647-4-git-send-email-dvlasenk@redhat.com> <53DBDDE1.5070805@zytor.com> <CAK1hOcML4guky7VutK1xc3YxNjy4K4bX_78p8+7rEhMW0ZuLdg@mail.gmail.com>
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On 08/01/2014 03:11 PM, Denys Vlasenko wrote:
>>
>> Could you please try to see if there is a measurable change in the
>> latency of a trivial syscall?
> 
> Will do.
> Something along the lines of "how long does it take to execute two
> gazillions of getppid()?"
> 

Something like that, yes, but you have to run enough data points so you
can determine if the difference is statistically significant or just noise.

	-hpa