Messages in this thread | | | From | "Adam Kropelin" <> | Subject | Re: [PATCH *] rmap VM 11c (RMAP IS A WINNER!) | Date | Sat, 19 Jan 2002 17:15:09 -0500 |
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(Andrea, the previous version of this mail wasn't supposed to go out yet. I fat-fingered and sent it before I was done. This is the full version.)
Andrea Arcangeli: > On Sat, Jan 19, 2002 at 01:39:22PM -0500, Adam Kropelin wrote: > > Andrea Arcangeli: > > > With -aa something sane along the above lines is: > > > > > > /bin/echo "10 2000 0 0 500 3000 30 5 0" > /proc/sys/vm/bdflush > > > > Unfortunately, those adjustments on top of 2.4.18-pre2aa2 set a new record for > > worst performance: 7:19. > > then please try to decrease the nfract variable again, the above set it > to 2000, if you've a slow harddisk maybe that's too much, so you can try > to set it to 500 again.
Yes, the harddisk is definitely slow: it's a hw RAID5 partition with older drives, so writes are pretty slow.
I tried various nfract settings:
/bin/echo "10 300 0 0 500 3000 30 5 0" > /proc/sys/vm/bdflush 7:33
/bin/echo "10 500 0 0 500 3000 30 5 0" > /proc/sys/vm/bdflush 6:00
/bin/echo "10 800 0 0 500 3000 30 5 0" > /proc/sys/vm/bdflush 7:17
nfract=500 seems to be the best and gets much closer to the performance of rmap and -ac. Writeout is still very bursty compared to the other kernels, but that may not really matter, I don't know.
> I'd also give a try with the below settings: > > /bin/echo "10 500 0 0 500 3000 80 8 0" > /proc/sys/vm/bdflush
7:08
<snip>
> Also just in case, I'd suggest to try to repeat each benchmark three > times, so we know we are not bitten by random variations in the numbers.
I've been doing a variation on that theme already. The numbers I've been reporting are best of 2 runs. I have never seen the 2 runs differ by more than +/- 10 seconds.
--Adam
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