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Date: Fri, 25 Jan 2002 18:10:12 -0800
From: Andrew Morton <akpm@zip.com.au>
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To: Linus Torvalds <torvalds@transmeta.com>
CC: Andi Kleen <ak@suse.de>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] syscall latency improvement #1
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Linus Torvalds wrote:
> 
> It should be eminently testable. Just remove the cli from the standard
> kernel, and do before-and-after tests.
> 

#include <unistd.h>

main()
{
        int i = 100 * 1000 * 1000;

        while (i--)
                getpid();
}

With cli:
	./a.out  22.05s user 15.31s system 99% cpu 37.361 total

without cli: 
	./a.out  18.29s user 17.42s system 99% cpu 35.731 total


That's 4.6%.  Intel P3.

It's also 306 cycles per iteration.  So the cli added 14 cycles.

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