Subject: Re: [linux-audio-dev] Disk use causes freezes
From: Juhana Sadeharju (kouhia_AT_nic.funet.fi)
Date: Wed Aug 01 2001 - 21:55:00 EEST
>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.
Hey, sorry, I will put it more clearly:
No program is using that much memory that the swap space is needed.
It looks like cp, md5sum, tar and/or flac program (which all have
handled large data for me) either use much memory, or Linux VM is
loading data always to a new memory location and eventually fills the
whole memory. I don't know if VM is really swapping anything when the
memory is completely filled. It could just take time to either have
a memory for a new program or get disk loading time for loading the
new program in to memory. Or, in the case of Emacs (freeze of 5
seconds), scheduler lowers the process priorities too much --- are
there any latencies caused by lowered priority in SCHED_USER mode?
I actually don't know details of Linux kernel. I'm sure both using
latest kernels and turning DMA on will help, but I would like to
have a test program which would tell me that the system should be
configured better for multimedia use, or that there could be something
wrong.
Regards,
Juhana
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