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SubjectRe: [bigmem-patch] 4GB with Linux on IA32
: On Mon, 16 Aug 1999, Matthew Wilcox wrote:
: >Have you got some lmbench results to back this up?
: Does lmbench benchmark the _allocation_ of the memory? If so could you
: point out to me the exact lmbench command? (you would save me the time for
: writing such a simple bench ;). I looked a bit at lmbench and it seems to
: me that all mm tools are measuring the time _after_ the allocation
: happened (so measuring the hardware bus/cache speed or page-colouring
: algorithms and not the OS anonymous/shm page-fault time). But maybe I am
: overlooking something?

lmbench's timing loops are loops, in other words they want to be able to do
something N times to get accurate numbers. The only time they don't run
it N times is if the run takes longer than some threshold, I think it was
either a second or 5 seconds.

If you tell me what you want to measure I can probably code up something
for you. Or tell you how to do it - there is a lot of infrastructure in
lmbench which makes writing new tests trivial and I would hope you would
do that. For example, suppose you had a new system call "sysWhizzy"
and you wanted to benchmark it. An lmbench program which would do that
would look like

#include "bench.h"

BENCH(sysWhizzy(args), 0);
micro("Whizzy", get_n());

Pretty easy, no?

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