From: Davide Libenzi <davidel@xmailserver.org>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: "Dieter Nützel" <Dieter.Nuetzel@hamburg.de>,
"Linux Kernel List" <linux-kernel@vger.kernel.org>
Subject: Re: 7.52 second kernel compile
Date: Mon, 18 Mar 2002 15:53:32 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.44.0203181541360.1606-100000@blue1.dev.mcafeelabs.com> (raw)
In-Reply-To: <Pine.LNX.4.33.0203181434440.10517-100000@penguin.transmeta.com>
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On Mon, 18 Mar 2002, Linus Torvalds wrote:
>
> On Mon, 18 Mar 2002, Dieter [iso-8859-15] Nützel wrote:
> >
> > it seems to be that it depends on gcc and flags.
>
> That instability doesn't seem to show up on a PII. Interesting. Looks like
> the athlon may be reordering TLB accesses, while the PII apparently
> doesn't.
>
> Or maybe the program is just flawed, and the interesting 1/8 pattern comes
> from something else altogether.
Umhh, something magic should happen inside the Athlon p/line to explain this :
processor : 0
vendor_id : AuthenticAMD
cpu family : 6
model : 4
model name : AMD Athlon(tm) Processor
stepping : 2
cpu MHz : 999.561
cache size : 256 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov
pat pse36 mmx fxsr syscall mmxext 3dnowext 3dnow
bogomips : 1992.29
$ gcc -o tlb_test tlb_test.c
#APP
rdtsc
#NO_APP
movl %eax, -16(%ebp)
movl -4(%ebp), %eax
addl -12(%ebp), %eax
movl (%eax), %eax
#APP
rdtsc
#NO_APP
movl %eax, -20(%ebp)
98.76: 21
$ gcc -O2 -o tlb_test tlb_test.c
#APP
rdtsc
#NO_APP
movl -16(%ebp), %edx
movl %eax, %ecx
movl (%ebx,%edx), %eax
#APP
rdtsc
#NO_APP
subl %ecx, %eax
97.59: 94
The only thing i can think is that stuff is moved between the two rdtsc
... maybe a barrier should help to have more consistent results.
- Davide
next prev parent reply other threads:[~2002-03-18 23:49 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-03-18 22:12 7.52 second kernel compile Dieter Nützel
2002-03-18 22:46 ` Linus Torvalds
2002-03-18 23:53 ` Davide Libenzi [this message]
2002-03-19 0:20 ` David S. Miller
2002-03-19 0:47 ` Davide Libenzi
2002-03-19 1:37 ` Andreas Ferber
2002-03-19 1:38 ` David S. Miller
2002-03-19 2:08 ` Linus Torvalds
2002-03-19 5:24 ` Erik Andersen
-- strict thread matches above, loose matches on Subject: below --
2002-03-13 8:52 10.31 " Anton Blanchard
2002-03-16 6:15 ` 7.52 " Anton Blanchard
2002-03-16 8:05 ` Linus Torvalds
2002-03-16 11:54 ` yodaiken
2002-03-16 11:04 ` Paul Mackerras
2002-03-16 18:32 ` Linus Torvalds
2002-03-17 2:00 ` Paul Mackerras
2002-03-17 2:40 ` Linus Torvalds
2002-03-17 2:50 ` M. Edward Borasky
2002-03-18 19:42 ` Cort Dougan
2002-03-18 20:04 ` Linus Torvalds
2002-03-18 20:23 ` Linus Torvalds
2002-03-18 21:50 ` Rene Herman
2002-03-18 22:36 ` Cort Dougan
2002-03-18 22:47 ` Linus Torvalds
2002-03-18 22:56 ` Cort Dougan
2002-03-18 23:52 ` Paul Mackerras
2002-03-19 0:57 ` Dave Jones
2002-03-19 3:35 ` Jeff Garzik
2002-03-19 0:22 ` David S. Miller
2002-03-19 0:27 ` Cort Dougan
2002-03-19 0:27 ` David S. Miller
2002-03-19 0:36 ` Cort Dougan
2002-03-19 0:38 ` David S. Miller
2002-03-19 1:28 ` Davide Libenzi
2002-03-19 2:42 ` Paul Mackerras
2002-03-27 2:53 ` Richard Henderson
2002-04-02 4:32 ` Linus Torvalds
2002-04-02 10:50 ` Pablo Alcaraz
2002-03-18 21:34 ` Cort Dougan
2002-03-18 22:00 ` Linus Torvalds
2002-03-18 19:37 ` Cort Dougan
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