Subject: Re: Nice 20 process running despite needed CPU time
To: R. C. Dowdeswell <firstname.lastname@example.org>
From: Bjoern Labitzke <email@example.com>
Date: 05/02/2000 16:02:33
* R. C. Dowdeswell (firstname.lastname@example.org) [000502 15:39]:
| On 957225444 seconds since the Beginning of the UNIX epoch
| Bjoern Labitzke wrote:
| >To summarize: Processes with a nice value of 20 don't get CPU cycles, if
| >processes with values <=0 need them, _unless_ one or more processes with a
| >value between 1 and 18 are using cycles as well.
| >It seems to me, that this behaviour is not correct. If it is the intended
| >behaviour, the setpriority man page should be changed appropriatly. Or do I
| >miss something?
| I tried this with busy loops on alpha and I couldn't reproduce your results,
| are you sure that lame isn't being niced to 4 because of its accumulated CPU
ps -axu output:
USER PID %CPU %MEM VSZ RSS TT STAT STARTED TIME COMMAND
hermit 409 88.6 10.6 620 13780 E4 R+ 3:45PM 4:46.00 ./setiathome -n
hermit 427 6.6 0.9 1108 1220 E3 DN 3:47PM 0:12.06 cvs -d anoncvs@
hermit 151 2.5 0.3 604 384 ?? RNs 3:13PM 28:40.96 /usr/local/dnet
[non-relevant rest of output cut]
ps -lax output
UID PID PPID CPU PRI NI VSZ RSS WCHAN STAT TT TIME COMMAND
1001 151 1 0 68 20 604 384 - RNs ?? 28:46.02 /usr/local/dn
1001 427 425 5 -5 10 1212 1344 biowai DN E3 0:23.18 cvs -d anoncv
1001 409 146 33 61 0 620 12752 - R+ E4 7:46.97 ./setiathome
As you can see I am running setiathome for this test with nice level 0, cvs
with nice level 10 and the dnet-client with nice level 20. Before starting
the cvs client, setiathome got all the CPU cycles, dnet none. Since starting
cvs dnet gets 0.5-10.0% of the cycles!
But I could not reproduce this behaviour with two seticlients, from which I
niced one to 10. In that scenario dnet got no cycles. So perhaps the problem
occurs only, if the kernel (e.g. for file io) is used. Is this reproducable?
(For me it is, as the above example shows.) Any ideas what I might try as well
to limit the possible scope of the problem?
Bjoern Labitzke <email@example.com>
Use PGP! (Don't you use envelopes for your letters?)