Re: SUMMARY: A nice(1) question.

From: Szymon Sokol (
Date: Thu Aug 12 1993 - 05:08:33 CDT

Rick Morris ( wrote:

: My question was thus:

: In article <> I wrote:
: > Question: If all other processes are running with a nice
: > value of 0, does it make a difference if the background
: > process runs at a nice value of 4 or 19?

: Many thanks to the folks who responded. If I forgot you, thanks
: too.

[many answers deleted, this one left:]

: Be careful of using nice on anything that isn't CPU bound. I believe
: it's possible for the scheduling and paging algorithms to interfere
: adversely. (I'm having trouble thinking of a watertight example
: though, so maybe this is just urban legend.)

This is interesting. Recently we had a user who allocated much more memory to
his process than the size of physical RAM, so the machine was paging heavily.
'renice' did not help much, because the bottleneck was on the disk, not on the
CPU (in fact, CPU was used in ~70% only - our 690 has 2 CPUs). I wonder though,
if the problem mentioned above (the interference between the scheduling and
paging algorithms) really exists, and if so - how does it affect performance.
Would any Unix kernel wizards care to explain?

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