Messages in this thread | | | Date | Fri, 8 Jan 1999 23:28:16 -0700 (MST) | From | Dax Kelson <> | Subject | 2.2.0-pre[56] swap performance poor with > 1 thrashing task |
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On 7 Jan 1999, Zlatko Calusic wrote:
> 2.2.0-pre5 works very good, indeed, but it still has some not > sufficiently explored nuisances: > > 1) Swap performance in pre-5 is much worse compared to pre-4 in > *certain* circumstances. I'm using quite stupid and unintelligent > program to check for raw swap speed (attached below). With 64 MB of > RAM I usually run it as 'hogmem 100 3' and watch for result which is > recently around 6 MB/sec. But when I lately decided to start two > instances of it like "hogmem 50 3 & hogmem 50 3 &" in pre-4 I got 2 x > 2.5 MB/sec and in pre-5 it is only 2 x 1 MB/sec and disk is making > very weird and frightening sounds. My conclusion is that now (pre-5) > system behaves much poorer when we have more than one thrashing > task. *Please*, check this, it is a quite serious problem.
I just tried this on 2.2.0-pre6 PentiumII 412Mhz, 128MB SDRAM, one IDE disk (/ & swap).
./hogmem 100 3 (no swapping) Memory speed: 167.60 MB/sec
./hogmem 200 3 Memory speed: 9.01 MB/sec
./hogmem 100 3 & ./hogmem 100 3 Memory speed: 0.96 MB/sec Memory speed: 0.96 MB/sec
./hogmem 100 3 (no swap) Memory speed: 180.18 MB/sec
./hogmem 200 3 Memory speed: 8.68 MB/sec
I then tried
./hogmem 200 3 &
find / (on about 1.5GB of data on ext2 and vfat and nfs repeatedly)
And launched netscape. After 45 mins, I didn't restart the find, and about 3 mins later the hogmem completed at 0.75MB/sec. Netscape was surprisingly responsive however.
Dax Kelson
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