Messages in this thread | | | Date | Mon, 29 Apr 1996 01:09:25 +0200 | From | (Benoit Poulot-Cazajous) | Subject | Re: Bad 1.3.95 interactive performance |
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Matthias Sattler <m_sattle@informatik.uni-kl.de> wrote :
> With 1.3.95 and some kernels before (i don't know exactly when it started) > I notice unnecessary heavy swapping activity when the system is up some time. > ... > As long as the working set does not change everything is normal, but even > the smallest change results in heavy swapping (while the output of free > looks normal). > ... > What can I do to fine out more about the nature of this problem (yes I will > try the normal ncr driver...) ?
It may be a problem in the buffer cache management. How big is your buffer cache when performance is so bad ?
To know if the buffer cache is too small, run 'hdparm -t /dev/hda'. If hdparm complains, there is one more victim of the page cache vs buffer cache fight... If you want to join the club, try this : # dd if=/dev/zero of=foobar bs=$[1024*1024] count=32 32+0 records in 32+0 records out # cp foobar /dev/null # hdparm -t /dev/hda /dev/hda: Timing buffer-cache reads: 32 MB in 6.03 seconds = 5.31 MB/sec Timing buffered disk reads: 16 MB in 2.66 seconds = 6.02 MB/sec Hmm.. suspicious results: probably not enough free memory for a proper test.
-- Benoit
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