Re: [OT]Re: Multi-tasking
Raúl Sánchez Siles:
> Here is something I have always liked to asks but I hadn't had the
> chance. The problem is that on my job PC, I use reiser over a LVM over a
> SATA disk. When I have some disk intensive tasks/intervals, my system
> turns not as responsive as I wish and as I think should be.
One part of the problem is crappy PC hardware :-\. Most certainly, the SATA
tranfers block the PCI bus and use up parts of your memory bandwidth while
transfering data, which is a bad thing. The other part (even with
non-crap) - you're putting heavy load on your disk subsystem from one
process. Now, if another process tries to do disk i/o, the heavy load from
the other process slows it down.
> In this situation, I have tried doing top on a konsole, and I find
> that the field "wa" in the above part of the top report, in the middle
> of "id" and "hi" raises to 80-90%. I don't know what exactly this field
> means, but I bet for cpu-wait state as it is the case in disk I/O.
It's the amount of time, your systems spends waiting for i/o requests to
finish, and its quite normal to have 90%+ i/o wait while you're doing disk
i/o. In an ideal world, the disk operation should not influence the rest
of the system too much (apart from slowing down other disk i/o.)
> All of this guessing yields me to the conclusion that I'm sometimes
> wasting up to 90% of cpu time waiting or just doing nothing, I can't
If you're not typing very, very fast (or run some seti stuff in the
background all the time), your system spends nearly 100% of it's time
doing nothing ;-).
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