strange swap behaviour - test11pre4
Hi
This seems strange to me:
(from vmstat 1):
procs memory swap io system cpu
r b w swpd free buff cache si so bi bo in cs us sy id
1 0 0 107252 956 204 44024 2376 4 594 1 256 304 11 4 85 0 1 0 107272 952 204 43980 2436 60 641 15 284 324 5 7 88 1 0 0 107308 952 204 43976 2344 68 586 31 256 279 5 9 86 2 0 0 107284 952 204 43916 1488 24 372 6 199 257 5 6 89 0 1 0 107268 952 204 43840 2328 12 582 13 259 294 5 2 93 1 0 0 107252 952 204 43780 2580 32 645 8 272 312 12 1 87 0 1 0 107220 952 204 43680 2436 4 643 1 290 298 13 3 84 2 0 0 107176 952 204 43580 2324 0 581 10 273 299 10 3 87 0 1 0 107216 956 204 43576 2532 84 633 21 296 298 6 5 89 1 0 0 107172 952 204 43484 1948 0 487 0 251 273 6 2 92 0 1 0 107152 956 204 43420 2348 24 593 6 266 288 5 5 90
There is a perl program running (80 Meg's in size, 20 Megs resident) that is chatting to a database and building up a large hash in memory. The machine has 64M of RAM. The bit that doesn't make sense is why the cache is so large - the VM seems to have got stuck paging in stuff from swap repeatedly (bits of the perl program it would seem). Surely it should shrink the cache to provide more breathing room or am I being an idiot about this?
Should I be running a different kernel? 2.2.19preXXX ? Should I be tuning vm things in proc and if so how?
Thank you,
--Craig
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[snip, vmstat stuff, me]
Quoted 6 lines
There is a perl program running (80 Meg's in size, 20 Megs resident) that is chatting to a database and building up a large hash in memory. The machine has 64M of RAM. The bit that doesn't make sense is why the cache is so large - the VM seems to have got stuck paging in stuff from swap repeatedly (bits of the perl program it would seem). Surely it should shrink the cache to provide more breathing room or am I being an idiot about this?
$idiot++;
Quoted 2 lines
Should I be running a different kernel? 2.2.19preXXX ? Should I be tuning vm things in proc and if so how?
Hmmmm ... I think more RAM will help. I was hoping that it was some VM problem but having tested 2.2.19pre5 now (which does seem 'better' - it keeps about 45M of the program resident) it seems as if program really is keen on actually using most of the 80Megs it has allocated ... sheesh ... it makes mozilla look lean.
My apologies for the noise ...
--Craig
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Quoted 10 lines · Craig Schlenter
[snip, vmstat stuff, me]
Quoted 7 lines
There is a perl program running (80 Meg's in size, 20 Megs resident) that is chatting to a database and building up a large hash in memory. The machine has 64M of RAM. The bit that doesn't make sense is why the cache is so large - the VM seems to have got stuck paging in stuff from swap repeatedly (bits of the perl program it would seem). Surely it should shrink the cache to provide more breathing room or am I being an idiot about this?
$idiot++;
You probably got fooled by the new vm: All shm pages are now in the page cache and thus appear as 'cached'. But they cannot be shrinked away...
So I would vote for $idiot--; ;-)
Greetings
Christoph
P.S: I expect this to become an FAQ
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