Subject: Re: [linux-audio-dev] Disk use causes freezes
From: Andre Pang (ozone_AT_algorithm.com.au)
Date: Wed Aug 01 2001 - 16:56:10 EEST
On Wed, Aug 01, 2001 at 03:19:35PM +0300, Juhana Sadeharju wrote:
> I'm a bit worried about it because Debian 2.2 rev 2 is behaving similarly.
> If I copy large files, or perform md5sums on large files, it may take even
> 45 seconds before I get the password prompt on the console or get
> a directory listing. Typically it takes 25-30 seconds. Writing text in
> Emacs may have 4-5 seconds latency; sometimes larger.
Juhana, if i understand you correctly, are you saying that Linux
has extremely bad latency when you're deep into swap space? if
you are, that can't be helped. if Linux needs to swap things
back into memory to get the next task to run, then it needs to
swap things into memory. disks are slow.
> Yes I have a swap space, and it looks like it is taking all the power of
> Linux under disk use (entire memory is filled with md5summed file and no
> room is left to other processes). It could be wise to take swap away if
> one is expected to use an audio editor in real-time, but that should not
> be the solution to the problem.
unless somebody thinks of a better idea, i think that if you're
really after 'real-time' performance from things like audio
editors, then you cannot use swap. if it is utterly critical
that you don't swap out, then, yes, you must lock your pages and
declare them unswappable. (cdrdao and cdrecord do this for
their buffer pages so your burner doesn't have an underrun
halfway.) Linux is smart enough to keep your current 'working
set' in memory; it will swap the least active programs out to
disk. no operating system can save you if your current working
set exceeds the amount of real RAM you have on the system.
am i reading you correctly or am i misinterpreting what you
wrote?
-- #ozone/algorithm <ozone_AT_algorithm.com.au> - trust.in.love.to.save
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