Messages in this thread | | | Date | Wed, 17 Dec 2003 20:49:51 +0100 | From | Roger Luethi <> | Subject | Re: 2.6.0-test9 - poor swap performance on low end machines |
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On Wed, 17 Dec 2003 13:53:28 -0500, Rik van Riel wrote: > On Tue, 16 Dec 2003, Roger Luethi wrote: > > > One potential problem with the benchmarks is that my test box has > > just one bar with 256 MB RAM. The kbuild and efax tests were run with > > mem=64M and mem=32M, respectively. If the difference between mem=32M > > OK, I found another difference with 2.4. > > Try "echo 256 > /proc/sys/vm/min_free_kbytes", I think > that should give the same free watermarks that 2.4 has.
I played around with that knob after wli posted his findings in the "mem=16MB laptop testing" thread. IIRC tweaking min_free_kbytes didn't help nearly as much as I had hoped. I'm running the efax benchmark right now just to make sure. It's going to take a couple of hours, I'll follow up with results.
FWIW akpm posted a patch to initialize min_free_kbytes depending on available RAM which seemed to make sense but it hasn't made it into mainline yet.
> Using 1MB as the min free watermark for lowmem is bound > to result in more free (and less used) memory on systems > with less than 128 MB RAM ... significantly so on smaller > systems.
Possibly. If memory pressure is high enough, though, the allocator ignores the watermarks. And on the other end kswapd seems to be pretty busy anyway during the benchmarks.
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