Message-Id: <3.0.32.19990713233149.0110d2f0@pop.xs4all.nl>
X-Sender: diep AT pop DOT xs4all DOT nl
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Date: Tue, 13 Jul 1999 23:31:51 +0100
To: pgcc AT delorie DOT com
From: Vincent Diepeveen <diep AT xs4all DOT nl>
Subject: Re: Kernel Optimization and RH 6
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Reply-To: pgcc AT delorie DOT com

At 05:20 PM 7/12/99 -0600, you wrote:
>Are the lines below the best option to compile a 2.2.x kernel with
egcs/pgcc running
>on a Pentium II?

-mpentiumpro gives me several tens of slower code for my programs
using pgcc or gcc or egcs

I'm having a pentium pro 200 and a PII-450

Greetings,
Vincent
>-O6 -mpentiumpro -march=pentiumpro -malign-function=2
>-malign-jumps=2 -malign-loops=2 -fomit-frame-pointer
>-fstrength-reduce
>
>Background
>
>We have recently installed RedHat 6 on a PowerEdge 4300, PII 350Mhz with
256MB
>of RAM.  RedHat 6 determines the type of processor and installs the compiled
>kernel accordingly.  This kernel has been compiled with the "best"
performance
>optimizations depending on the hardware. 
>
>As a non-scientific measure of this kernel performance, at boot time, the
>RAID 5 routines reached 850MB/s.  This measure can be seen after booting
in /var/log/messages
>
>After that, we updated the kernel to version 2.2.7, but we obtained only
835MB/s
>in the same measure.
>
>These are the options used and the compiler version:
>
>Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/egcs-2.91.66/specs
>gcc version egcs-2.91.66 19990314/Linux (egcs-1.1.2 release)
>
>We modify /usr/src/linux/Makefile like this:
>
>HOSTCC = egcs
>HOSTCFLAGS = -Wall -Wstrict-prototypes -O6 -fomit-frame-pointer
>CC = $(CROSS_COMPILE)egcs -D__KERNEL__ -I$(HPATH)
>
>
>And /usr/src/linux/arch/i386 as the following:
>
>CFLAGS_NSR := -fstrength-reduce
>ifdef CONFIG_M686
>CFLAGS := $(CFLAGS) -mpentiumpro -march=pentiumpro -malign-loops=2
>-malign-jumps=2 -malign-functions=2 -DCPU=686
>endif
>
>The machine is used as transparent proxy server with squid 2.2.stable3
(compiled
>with the same options)
>
>We didn't have any trouble at compilation time nor we had stability problems
>with egcs.  Squid is reaching the 50% Hit Ratio but is using too much CPU
time, 
>around 27% with 17% of system time and 10% of user time.
>
>I understand that optimizing the kernel is not what best improves
performance, but
>there is nothing else we could do to the PowerEdge 4300 with our current
budget, and
>given that the options used to compile RedHat 6 achieved a better throughput
>(850 versus 835) and that squid is using too much system time, 
>maybe there should be something that could be done to recompile the
>kernel and squid with egcs/pgcc and obtain some kind of improvement.
>
>I'll appreciate your advice on this.
>
>Regards,
>
>Rolando
>
>
>
>
>
>