I hope this is the appropriate place to ask this kind of question ... I
could'nt really find any useful info otherwise (web search). Here I go:
I use almost Linux mostly for all my computing needs -- both personal and
corporate. I've been extremely pleased for over 4 years. However
something bothers me.
I've noticed that under heavy loads, and actually, not so heavy loads,
Linux's responsiveness is effectively very poor.
2 cases I've encountered lately:
1 - My company has a MySQL-backed web server. We need to compute stats and
generate somewhat long series of queries on a regular basis (every n
minutes). The database fits entirely in the disk cache, AFAIK: the machine
is equipped with 300MB and the whole database is ~ 45MB. Now, as more
queries are concurrently issued (more than 1 at once), the responsiveness
gets worse. It's mostly significant when spawning new processes -- I.e
when logging in from telnet from instance, which takes a few seconds. The
system isn't even swapping, I can verify it. The load average in that case
is between 2 and 4. The system is a proliant 1600 with 1 PII-450.
It's not like there's a bunch of runaway processe: at most, 5 processes
are running.
2 - I was using a perl script to install the Unreal Tournament Bonus
pack .umod (basically a compressed package). The said script is marked as
not being optimised, and it used up to 230M of memory whereas I have 128M
of physical ram. Of course, it swapped a lot, as I expected it. But ...
the system was absolutely unusable during that time. Not just slow ...
absolutely unusable. Plus top showed it as 80% idle most of the time.
(The disk is connected using UDMA/33 on a BE6-2 MB, the system is a
PIII-450).
Now I *hear* (but is it true?) that *BSD handles this sort of case much
more nicely. Is it true? Is there anything planned to make linux perform
better in this area? Are there workarounds? Niceing the process doesn't
seem to do any good. Is there, for example, a way to force a process not
to consume more than a certain % of the CPU?
Thanks in advance for your help.
(Please CC me on the replies)
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