Re: Benchmarking objrmap under memory pressure

Martin J. Bligh
2004-04-13T07:55:57Z

--Andrew Morton <akpm@osdl.org> wrote (on Tuesday, April 13, 2004 00:51:11 -0700):

> "Martin J. Bligh" <mbligh@aracnet.com> wrote:
>>
>> UP Athlon 2100+ with 512Mb of RAM. Rebooted clean before each test
>> then did "make clean; make vmlinux; make clean". Then I timed a
>> "make -j 256 vmlinux" to get some testing under mem pressure.
>>
>> I was trying to test the overhead of objrmap under memory pressure,
>> but it seems it's actually distinctly negative overhead - rather pleasing
>> really ;-)
>>
>> 2.6.5
>> 225.18user 30.05system 6:33.72elapsed 64%CPU (0avgtext+0avgdata 0maxresident)k
>> 0inputs+0outputs (37590major+2604444minor)pagefaults 0swaps
>>
>> 2.6.5-anon_mm
>> 224.53user 26.00system 5:29.08elapsed 76%CPU (0avgtext+0avgdata 0maxresident)k
>> 0inputs+0outputs (29127major+2577211minor)pagefaults 0swaps
>
> A four second reduction in system time caused a one minute reduction in
> runtime? Pull the other one ;)

Look at the cpu percentage though. I presume it's blocked itself on disk IO.
Possibly because the space overhead of pte_chains causes more mem pressure.

> Average of five runs, please...

Maybe in the morning ;-). I mean ... a sensible time later this morning ;-)

M.