[PLUG] Morning Slugishness
Russell Senior
seniorr at aracnet.com
Mon Jul 31 20:57:24 UTC 2006
>>>>> "Daniel" == Daniel Hedlund <daniel at digitree.org> writes:
Daniel> [...] If I change the value to a low number such as 10 (or
Daniel> even 0, "echo 10 > /var/sys/vm/swappiness") just before
Daniel> running updatedb, the kernel will be very unlikely to swap out
Daniel> any memory unless it really really has to. Once updatedb is
Daniel> done, you can set the swappiness back to its previous value:
Daniel> http://lwn.net/Articles/83588/ http://kerneltrap.org/node/3000
Won't solve the problem (of applications laggily swapping back in).
Rsync on big jobs chews up lots of RAM (has to maintain a lookup of
visited inodes in order to get hardlinks right). That pressure is apt
to push idle jobs out of RAM.
Daniel> However, I think the easiest solution would be to either
Daniel> disable updatedb in the nightly cron job and make run it once
Daniel> a week.
Not a solution to nightly backups. The nightliness is a desired feature.
Daniel> There is also apparently a patch being proposed (not sure if
Daniel> it's been implemented in the main trunk yet), which would
Daniel> automatically reload certain applications back into memory
Daniel> after they've been paged out to swap
Daniel> (http://members.optusnet.com.au/ckolivas/kernel/index.html).
The ability to do something like that on a per-process basis could
solve the problem. Something like: swapin $(pidof mozilla)
Depending on the situation/machine, though, my swapoff/swapon trick
will work too. Thanks for pointing out the caution though. I am not
sure what happens if swapoff can't swap everything back in.
--
Russell Senior ``I have nine fingers; you have ten.''
seniorr at aracnet.com
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