Re: [SCHED] Totally WRONG prority calculation with specifictest-case (since 2.6.10-bk12)

From: Paolo Ornati
Date: Wed Dec 28 2005 - 05:20:28 EST

On Wed, 28 Dec 2005 10:59:13 +1100
Peter Williams <pwil3058@xxxxxxxxxxxxxx> wrote:

> Any chance of you applying the PlugSched patches and seeing how the
> other schedulers that it contains handle this situation?
>
> The patch at:
>
> <http://prdownloads.sourceforge.net/cpuse/plugsched-6.1.6-for-2.6.15-rc5.patch?download>
>
> should apply without problems to the 2.6.15-rc7 kernel.
>
> Very Brief Documentation:
>
> You can select a default scheduler at kernel build time. If you wish to
> boot with a scheduler other than the default it can be selected at boot
> time by adding:
>
> cpusched=<scheduler>
>
> to the boot command line where <scheduler> is one of: ingosched,
> nicksched, staircase, spa_no_frills, spa_ws, spa_svr or zaphod. If you
> don't change the default when you build the kernel the default scheduler
> will be ingosched (which is the normal scheduler).


First of all, this is the "pstree" structure of transcode an friends:

|-kdesktop---perl---sh---transcode-+-2*[sh-+-tccat]
| | |-tcdecode]
| | |-tcdemux]
| | `-tcextract]
| `-transcode---5*[transcode]


Results with various schedulers:

------------------------------------------------------------------------

1) nicksched: perfect! This is the behaviour I want.

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
5562 paolo 40 0 115m 18m 2428 R 82.2 3.7 0:22.16 transcode
5576 paolo 26 0 50348 4516 1912 S 9.5 0.9 0:02.43 tcdecode
5566 paolo 23 0 115m 18m 2428 S 4.6 3.7 0:01.24 transcode
5573 paolo 21 0 115m 18m 2428 S 0.9 3.7 0:00.22 transcode
5577 paolo 27 0 20356 1140 920 S 0.9 0.2 0:00.21 tcdemux
5295 root 20 0 167m 17m 3624 S 0.6 3.5 0:11.02 X
5579 paolo 20 0 47308 2540 1996 S 0.5 0.5 0:00.14 tcdecode
5574 paolo 20 0 20356 1144 920 S 0.4 0.2 0:00.11 tcdemux
...

transcode get recognized for what it is, and I/O bounded processes
don't even notice that it is running :)


2) staircase: bad, as you can see:

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
5582 paolo 26 0 115m 18m 2428 R 82.7 3.7 0:47.63 transcode
5599 paolo 39 0 50352 4516 1912 R 9.6 0.9 0:05.21 tcdecode
5586 paolo 0 0 115m 18m 2428 S 4.5 3.7 0:02.61 transcode
5622 paolo 39 0 4948 1520 412 R 1.1 0.3 0:00.15 dd
5591 paolo 0 0 115m 18m 2428 S 0.6 3.7 0:00.36 transcode
5575 paolo 0 0 98476 37m 9392 S 0.4 7.5 0:01.44 perl
5597 paolo 27 0 20356 1144 920 S 0.4 0.2 0:00.21 tcdemux
5475 paolo 0 0 86556 22m 15m S 0.2 4.5 0:01.24 konsole
5388 root 0 0 167m 17m 3208 S 0.1 3.4 0:03.16 X
5587 paolo 0 0 115m 18m 2428 S 0.1 3.7 0:00.03 transcode
5595 paolo 20 0 47312 2540 1996 S 0.1 0.5 0:00.14 tcdecode
5596 paolo 26 0 22672 1268 1020 S 0.1 0.2 0:00.03 tccat
5598 paolo 28 0 22364 1436 932 S 0.1 0.3 0:00.04 tcextract


And "DD" is affected badly:

paolo@tux /mnt $ mount space/; sync; sleep 1; time dd if=space/bigfile
of=/dev/null bs=1M count=128; umount space/ 128+0 records in
128+0 records out

real 0m6.341s
user 0m0.002s
sys 0m0.229s

While transcoding:

paolo@tux /mnt $ mount space/; sync; sleep 1; time dd if=space/bigfile
of=/dev/null bs=1M count=256; umount space/ 256+0 records in
256+0 records out

real 0m15.793s
user 0m0.001s
sys 0m0.374s


3) spa_no_frills: bad, but this is OK since it is Round Robin :)

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
5356 paolo 20 0 115m 18m 2428 R 81.1 3.7 0:27.61 transcode
5371 paolo 20 0 50348 4516 1912 R 8.9 0.9 0:02.97 tcdecode
5360 paolo 20 0 115m 18m 2428 S 4.1 3.7 0:01.54 transcode
5378 paolo 20 0 4948 1520 412 D 1.4 0.3 0:00.29 dd
5364 paolo 20 0 20352 1144 920 S 0.9 0.2 0:00.20 tcdemux
5373 paolo 20 0 115m 18m 2428 S 0.7 3.7 0:00.32 transcode
5369 paolo 20 0 20356 1144 920 S 0.5 0.2 0:00.14 tcdemux
5205 root 20 0 165m 15m 2584 R 0.2 3.2 0:01.86 X


4) spa_ws: bad

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
5334 paolo 32 0 115m 18m 2428 R 82.7 3.7 0:18.77 transcode
5349 paolo 32 0 50348 4516 1912 R 8.9 0.9 0:02.00 tcdecode
5338 paolo 21 0 115m 18m 2428 S 4.6 3.7 0:01.08 transcode
5356 paolo 32 0 4948 1520 412 D 1.1 0.3 0:00.12 dd
5351 paolo 32 0 115m 18m 2428 S 1.0 3.7 0:00.20 transcode
5199 root 21 0 165m 15m 2584 S 0.4 3.2 0:01.68 X
5347 paolo 32 0 20356 1140 920 S 0.4 0.2 0:00.08 tcdemux
5296 paolo 22 0 98472 37m 9392 S 0.2 7.5 0:01.47 perl
5299 paolo 21 0 86556 22m 15m S 0.2 4.4 0:00.75 konsole
5344 paolo 32 0 47308 2540 1996 S 0.2 0.5 0:00.07 tcdecode
5339 paolo 21 0 115m 18m 2428 S 0.1 3.7 0:00.01 transcode

paolo@tux /mnt $ mount space/; sync; sleep 1; time dd if=space/bigfile
of=/dev/null bs=1M count=256; umount space/ 256+0 records in
256+0 records out

real 0m8.112s
user 0m0.001s
sys 0m0.444s

paolo@tux /mnt $ mount space/; sync; sleep 1; time dd if=space/bigfile
of=/dev/null bs=1M count=256; umount space/ 256+0 records in
256+0 records out

real 0m29.222s
user 0m0.000s
sys 0m0.400s


5) spa_svr: surprise, surprise! Not all that bad. At least DD
gets better priority than transcode... and DD real time is only a bit
affected (8s --> ~9s).


PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
5334 paolo 33 0 115m 18m 2428 R 78.1 3.7 0:22.70 transcode
5349 paolo 28 0 50352 4516 1912 S 9.0 0.9 0:02.41 tcdecode
5338 paolo 25 0 115m 18m 2428 S 4.7 3.7 0:01.29 transcode
5363 paolo 27 0 4952 1520 412 R 4.7 0.3 0:00.25 dd
5342 paolo 33 0 20352 1140 920 S 1.6 0.2 0:00.21 tcdemux
5351 paolo 25 0 115m 18m 2428 S 0.8 3.7 0:00.23 transcode
5144 root 22 0 166m 16m 3120 S 0.4 3.3 0:01.85 X
5344 paolo 23 0 47308 2540 1996 S 0.4 0.5 0:00.13 tcdecode
5347 paolo 27 0 20356 1144 920 S 0.4 0.2 0:00.10 tcdemux
5231 paolo 22 0 86660 22m 15m S 0.2 4.5 0:00.95 konsole
5271 paolo 25 0 98476 37m 9396 S 0.2 7.5 0:01.54 perl
5341 paolo 23 0 22672 1268 1020 S 0.2 0.2 0:00.02 tccat


6) zaphod: more or less like spa_svr

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
5308 paolo 34 0 115m 18m 2428 R 52.1 3.7 0:49.77 transcode
5323 paolo 32 0 50352 4516 1912 S 6.0 0.9 0:05.61 tcdecode
5356 paolo 28 0 4952 1520 412 D 3.5 0.3 0:00.28 dd
5312 paolo 28 0 115m 18m 2428 S 2.6 3.7 0:02.71 transcode
5325 paolo 31 0 115m 18m 2428 S 0.7 3.7 0:00.55 transcode
5316 paolo 37 0 20352 1140 920 S 0.4 0.2 0:00.33 tcdemux
5202 root 23 0 165m 15m 2584 S 0.2 3.1 0:01.57 X
5318 paolo 31 0 47312 2540 1996 S 0.2 0.5 0:00.28 tcdecode
5321 paolo 33 0 20356 1144 920 S 0.2 0.2 0:00.26 tcdemux
4760 messageb 25 0 13248 1068 848 S 0.1 0.2 0:00.07
dbus-daemon-1 5264 paolo 24 0 93920 17m 10m S 0.1 3.5
0:00.38 kded 5282 paolo 23 0 92712 19m 12m S 0.1 3.9
0:00.36 kdesktop


7) ingosched: bad, as already said in the original post

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
5209 paolo 16 0 115m 18m 2428 R 72.0 3.7 0:22.13 transcode
5224 paolo 22 0 50348 4516 1912 R 8.4 0.9 0:02.44 tcdecode
5213 paolo 15 0 115m 18m 2428 S 4.2 3.7 0:01.24 transcode
5243 paolo 18 0 4948 1520 412 R 1.8 0.3 0:00.14 dd
5217 paolo 19 0 20356 1144 920 R 0.8 0.2 0:00.19 tcdemux
5108 root 15 0 165m 15m 2584 S 0.6 3.1 0:01.44 X
5226 paolo 15 0 115m 18m 2428 S 0.6 3.7 0:00.20 transcode
5216 paolo 18 0 22676 1268 1020 S 0.4 0.2 0:00.03 tccat
5219 paolo 18 0 47312 2540 1996 R 0.4 0.5 0:00.12 tcdecode
5222 paolo 18 0 20356 1144 920 S 0.4 0.2 0:00.10 tcdemux
5195 paolo 16 0 98488 37m 9392 S 0.2 7.5 0:01.41 perl
5198 paolo 16 0 86552 22m 15m R 0.2 4.4 0:00.66 konsole

paolo@tux /mnt $ mount space/; sync; sleep 1; time dd if=space/bigfile of=/dev/null bs=1M count=256; umount space/
256+0 records in
256+0 records out

real 0m23.393s (instead of 8s)
user 0m0.001s
sys 0m0.418s

------------------------------------------------------------------------


So the winner for manifest superiority is "nicksched", it looks to me
even better than 2.6.10-bk12 (ingosched) with
"remove_interactive_credit" reverted.

:)

--
Paolo Ornati
Linux 2.6.15-rc5-plugsched on x86_64
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