Date: Sun, 28 Nov 2010 18:26:24 +1100 From: Peter Jeremy <peterjeremy@acm.org> To: freebsd-stable@freebsd.org Subject: idprio processes slowing down system Message-ID: <20101128072624.GA76358@server.vk2pj.dyndns.org>
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Since scheduler issues have been popular lately, I thought I'd
investigate a ULE issue I've been aware of for a while...
I normally have some boinc (ports/astro/boinc) applications running
and I'd noticed that my nightly builds appear to end much sooner when
there's no boinc work units (this has been common for setiathome).
This morning, I timed 4 "make -j3 KERNCONF=GENERIC buildkernel" of
8-stable with the following results:
boinc running:
1167.839u 287.055s 18:45.69 129.2% 6140+1975k 1+0io 114pf+0w
1166.431u 288.265s 18:00.16 134.6% 6139+1975k 0+0io 106pf+0w
1168.490u 287.599s 17:52.24 135.7% 6137+1975k 0+0io 106pf+0w
1165.747u 287.641s 17:10.38 141.0% 6138+1975k 0+0io 106pf+0w
boinc stopped:
1165.052u 291.492s 15:54.72 152.5% 6125+1972k 0+0io 106pf+0w
1166.101u 290.305s 15:42.54 154.5% 6132+1973k 0+0io 106pf+0w
1165.248u 290.335s 15:35.93 155.5% 6132+1974k 0+0io 106pf+0w
1166.100u 289.749s 15:26.35 157.1% 6137+1974k 0+0io 106pf+0w
Since the the results were all monotonically reducing in wallclock
time, I decided to do a further 4 buildkernels with boinc running:
1168.242u 284.693s 17:33.05 137.9% 6140+1975k 0+0io 106pf+0w
1167.191u 285.332s 17:19.27 139.7% 6140+1976k 0+0io 106pf+0w
1224.813u 291.963s 20:14.90 124.8% 6121+1966k 0+0io 106pf+0w
1213.132u 294.564s 19:48.98 126.8% 6116+1967k 0+0io 106pf+0w
ministat(1) reports there is no statistical difference in the user
or system time:
User time:
x boinc_running
+ boinc_stopped
+----------------------------------------------------------------------+
| +* x |
| +*xx x x|
||________|A_M___________A_______________________| |
+----------------------------------------------------------------------+
N Min Max Median Avg Stddev
x 8 1165.747 1224.813 1168.242 1180.2356 24.12896
+ 4 1165.052 1166.101 1166.1 1165.6253 0.55457454
No difference proven at 95.0% confidence
System time:
x boinc_running
+ boinc_stopped
+----------------------------------------------------------------------+
| + |
|x x x xx x + + + x x|
| |_________________M____A________|___MA_____|__| |
+----------------------------------------------------------------------+
N Min Max Median Avg Stddev
x 8 284.693 294.564 287.641 288.389 3.3142183
+ 4 289.749 291.492 290.335 290.47025 0.73252412
No difference proven at 95.0% confidence
But there is a significant difference in the wallclock time:
x boinc_running
+ boinc_stopped
+----------------------------------------------------------------------+
|+ + + + x x x x x x x x|
||__AM_| |___________M____A_______________| |
+----------------------------------------------------------------------+
N Min Max Median Avg Stddev
x 8 1030.38 1214.9 1080.16 1100.5838 69.364795
+ 4 926.35 954.72 942.54 939.885 11.915879
Difference at 95.0% confidence
-160.699 +/- 79.6798
-14.6012% +/- 7.23977%
(Student's t, pooled s = 58.4006)
Since all the boinc processes are running at i31, why are they impacting
a buildkernel that runs with 0 nicety?
System information: AMD Athlon(tm) Dual Core Processor 4850e
(2511.45-MHz K8-class CPU) running FreeBSD/amd64 from just before
8.1-RELEASE with WITNESS and WITNESS_SKIPSPIN, 8GB RAM, src and obj
are both on ZFS.
--
Peter Jeremy
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