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SubjectRe: 2.2.5 optimizations for web benchmarks?
> for a web benchmark. I understand many of the tunables 
> in /proc/sys, but I'm not sure if I'm missing something
> crucial.

You actually probably don't need to tune them

> Assuming fast hardware, with lots of RAM (ranging from
> 512MB - 2GB), and with/without RAID (software), and a
> fast network (yellowfin or eepro100), and ext2fs.

For 2Gig of RAM you want to recompile as per the directions in the
kernel tree (include/asm-i386/page.h) to use an offset of 0x80000000.

> What should I change at 2.2.5 compile time? I'm
> especially curious if increasing the initial tcp cwnd
> to min (4380, 4*MSS) as suggested by IETF/tcpimpl would

It will do for an http/1.0 test, it doesn't for real world. You can tell
if its a factor because you will see much less than 100% CPU usage and
that adding clients increases performance.

> connections of the benchmark (I presume I'd have to
> change both snd_cwnd and snd_cwnd_cnt)


> Will I get any benefit from changing the tunables in eepro100.c and
> yellowfin.c ?

There is nothing there you need to touch

> inode-max
> bdflush
> buffermem
> freepages
> kswapd
> pagecache
> Any other I'm missing ?

You shouldnt need to touch those either.

> I'm using many of the common apache 1.4.3
> optimizations. Is there anything I can do to improve
> SMP performance, to help the built in affinity-scheme
> of linux?

Apache does fine with the default CPU affinity. You probably need to tune
the apache configuration more than anything else. You want the logging and
swap on a different disk to the pages and to the system preferably. For the
raid you want striping (obviously) and the raid howto/tools tell you how
to find the optimal stripe size.

If you want to answer the question "how fast is linux as a web server"
consider benchmarking using Zeus ( too.


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