Re: [ANNOUNCE] Staircase Deadline cpu scheduler version 0.45

From: Willy Tarreau
Date: Sun Apr 22 2007 - 04:09:07 EST


On Sun, Apr 22, 2007 at 05:31:58PM +1000, Con Kolivas wrote:
> On Sunday 22 April 2007 17:27, Con Kolivas wrote:
> > On Sunday 22 April 2007 17:00, Willy Tarreau wrote:
> > > On Sun, Apr 22, 2007 at 02:41:48PM +1000, Con Kolivas wrote:
> > > > A significant bugfix for SMP balancing was just posted for the
> > > > staircase deadline cpu scheduler which improves behaviour dramatically
> > > > on any SMP machine.
> > > >
> > > > Thanks to Willy Tarreau for noticing likely fault point.
> > > >
> > > > Also requested was a version in the Makefile so this version of the
> > > > patch adds -sd045 to the kernel version.
> > >
> > > Con, I'm sorry, but it is worse with this one :-(
> >
> > Well that was quick testing, thanks.
> >
> > > The lag when typing in xterms is even more noticeable and vmstat output
> > > oscillates between 8 and 65, with idle rates around 50%, as you can see
> > > below :
> > >
> > > Renicing X or not does not change anything here.
> > >
> > > I suspect that the bug you fixed was hiding another one :-/
> > > If you want me to test another patch, feel free to ask.
>
> Just as a debug point could you please try this patch? Thanks.

OK, this time, the ocbench took ages to start. They appeared immediately
but very few of them (less than 8 out of 64) really started to work. The
system remained very responsive and smooth during the test. But I guess
I know why : all the load was sent to CPU 0 :

procs memory swap io system cpu
r b w swpd free buff cache si so bi bo in cs us sy id
63 0 0 0 923476 6516 57456 0 0 0 28 175 1281 14 26 59
64 0 2 0 922976 6516 57456 0 0 0 0 4 261 19 31 50
64 0 0 0 922924 6516 57492 0 0 0 0 1 85 17 33 50
64 0 0 0 922924 6516 57492 0 0 0 0 0 110 25 25 50
64 0 1 0 922924 6516 57492 0 0 0 0 3 83 24 27 50
64 0 0 0 922924 6516 57492 0 0 0 4 16 267 18 33 50
64 0 0 0 922924 6516 57492 0 0 0 0 15 244 24 27 50
64 0 0 0 922956 6516 57492 0 0 0 0 8 200 20 31 49
59 0 0 0 922956 6516 57492 0 0 0 0 1 98 18 34 49
59 0 0 0 922956 6516 57492 0 0 0 0 0 105 21 30 49
64 0 0 0 922956 6516 57492 0 0 0 0 1 97 19 32 49
62 0 0 0 922972 6516 57492 0 0 0 0 0 114 23 28 49
64 0 0 0 922972 6516 57492 0 0 0 0 1 95 23 28 49
64 0 0 0 922972 6516 57492 0 0 0 0 0 104 22 29 49


CPU0 states: 45.0% user 54.0% system 0.0% nice 0.0% iowait 0.0% idle
CPU1 states: 0.1% user 0.0% system 0.0% nice 0.0% iowait 99.0% idle
Mem: 1034876k av, 112296k used, 922580k free, 0k shrd, 6524k buff
34232k active, 45428k inactive
Swap: 497972k av, 0k used, 497972k free 57536k cached

PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME CPU COMMAND
1402 willy 31 0 2272 640 548 R 2.9 0.0 0:00 0 ocbench
1407 willy 31 0 2272 640 548 R 2.9 0.0 0:00 0 ocbench
1452 willy 31 0 2272 640 548 R 2.9 0.0 0:00 0 ocbench
1455 willy 31 0 2272 640 548 R 2.9 0.0 0:00 0 ocbench
1394 willy 29 0 2272 640 548 R 1.9 0.0 0:00 0 ocbench
1395 willy 29 0 2272 640 548 R 1.9 0.0 0:00 0 ocbench
1396 willy 31 0 2272 640 548 R 1.9 0.0 0:00 0 ocbench
1400 willy 31 0 2272 640 548 R 1.9 0.0 0:00 0 ocbench
1401 willy 29 0 2272 640 548 R 1.9 0.0 0:00 0 ocbench
1404 willy 31 0 2272 640 548 R 1.9 0.0 0:00 0 ocbench
1408 willy 31 0 2272 640 548 R 1.9 0.0 0:00 0 ocbench
1409 willy 31 0 2272 640 548 R 1.9 0.0 0:00 0 ocbench
1411 willy 31 0 2272 640 548 R 1.9 0.0 0:00 0 ocbench
1412 willy 31 0 2272 640 548 R 1.9 0.0 0:00 0 ocbench
1413 willy 31 0 2272 640 548 R 1.9 0.0 0:00 0 ocbench


Willy

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