On Fri, 17 Oct 2003, Bruce Evans wrote: > How would one test if it was an improvement on the 4BSD scheduler? It > is not even competitive in my simple tests. [scripts results deleted] > > Summary: SCHED_ULE was more than twice as slow as SCHED_4BSD for the > obj and depend stages. These stages have little parallelism. SCHED_ULE > was only 19% slower for the all stage. It apparently misses many > oppurtunities to actually run useful processes. This may be related > to /usr being nfs mounted. There is lots of idling waiting for nfs > even in the SCHED_4BSD case. The system times are smaller for SCHED_ULE, > but this might not be significant. E.g., zeroing pages can account > for several percent of the system time in buildworld, but on unbalanced > systems that have too much idle time most page zero gets done in idle > time and doesn't show up in the system time. At one point ULE was at least as fast as 4BSD and in most cases faster. This is a regression. I'll sort it out soon. > > Test 1 for fair scheduling related to niceness: > > for i in 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 > do > nice -$i sh -c "while :; do echo -n;done" & > done > top -o time > > [Output deleted]. This shows only a vague correlation between niceness > and runtime for SCHED_ULE. However, top -o cpu shows a strong correlation > between %CPU and niceness. Apparently, %CPU is very innacurate and/or > not enough history is kept for long-term scheduling to be fair. > > Test 5 for fair scheduling related to niceness: > > for i in -20 -16 -12 -8 -4 0 4 8 12 16 20 > do > nice -$i sh -c "while :; do echo -n;done" & > done > time top -o cpu > > With SCHED_ULE, this now hangs the system, but it worked yesterday. Today > it doesn't get as far as running top and it stops the nfs server responding. > To unhang the system and see what the above does, run a shell at rtprio 0 > and start top before the above, and use top to kill processes (I normally > use "killall sh" to kill all the shells generated by tests 1-5, but killall > doesn't work if it is on nfs when the nfs server is not responding). 661 root 112 -20 900K 608K RUN 0:24 27.80% 27.64% sh 662 root 114 -16 900K 608K RUN 0:19 12.43% 12.35% sh 663 root 114 -12 900K 608K RUN 0:15 10.66% 10.60% sh 664 root 114 -8 900K 608K RUN 0:11 9.38% 9.33% sh 665 root 115 -4 900K 608K RUN 0:10 7.91% 7.86% sh 666 root 115 0 900K 608K RUN 0:07 6.83% 6.79% sh 667 root 115 4 900K 608K RUN 0:06 5.01% 4.98% sh 668 root 115 8 900K 608K RUN 0:04 3.83% 3.81% sh 669 root 115 12 900K 608K RUN 0:02 2.21% 2.20% sh 670 root 115 16 900K 608K RUN 0:01 0.93% 0.93% sh I think you cvsup'd at a bad time. I fixed a bug that would have caused the system to lock up in this case late last night. On my system it freezes for a few seconds and then returns. I can stop that by turning down the interactivity threshold. Thanks, Jeff > > Bruce > _______________________________________________ > freebsd-current_at_freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_freebsd.org" >Received on Thu Oct 16 2003 - 21:28:26 UTC
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