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SubjectRe: Phoronix CFS vs BFS bencharks
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On Mon, 2009-09-14 at 22:49 +0200, Willy Tarreau wrote:
> On Mon, Sep 14, 2009 at 09:14:35PM +0200, Marcin Letyns wrote:
> > 2009/9/14 Mike Galbraith <efault@gmx.de>
> > >
> > > On Mon, 2009-09-14 at 16:27 +0200, Marcin Letyns wrote:
> > > > Hello,
> > > >
> > > > Disabling NEW_FAIR_SLEEPERS makes a lot of difference here in the
> > > > Apache benchmark:
> > > >
> > > > 2.6.30.6-bfs: 7311.05
> > > >
> > > > 2.6.30.6-cfs-fair_sl_disabled: 8249.17
> > > >
> > > > 2.6.30.6-cfs-fair_sl_enabled: 4894.99
> > >
> > > Wow.
> > >
> > > Some loads like wakeup preemption (mysql+oltp), and some hate it. This
> > > load appears to REALLY hate it (as does volanomark, but that thing is
> > > extremely overloaded). How many threads does that benchmark run
> > > concurrently?
> >
> > >From the benchmark description:
> >
> > This is a test of ab, which is the Apache Benchmark program. This test
> > profile measures how many requests per second a given system can
> > sustain when carrying out 500,000 requests with 100 requests being
> > carried out concurrently.
>
> Be careful not to run ab on the same machine as you run apache, otherwise
> the numerous apache processes can limit ab's throughput. This is the same
> reason as why I educate people so that they don't run a single-process
> proxy in front of a multi-process/multi-thread web server. Apparently
> it's not obvious to everyone.

I turned on apache, and played with ab a bit, and yup, ab is a hog, so
any fairness hurts it a badly. Ergo, running ab on the same box as
apache suffers with CFS when NEW_FAIR_SLEEPERS are turned on. Issuing
ab bandwidth to match it's 1:N pig nature brings throughput right back.

(In all the comparison testing I've done, BFS favors hogs, and with
NEW_FAIR_SLEEPERS turned off, so does CFS, though not as much.)

Running apache on one core and ab on another (with shared cache tho),
something went south with BFS. I would have expected it to be much
closer (shrug).

Some likely not very uninteresting numbers below. I wasted a lot more
of my time generating them than anyone will downloading them :)

ab -n 500000 -c 100 http://localhost/openSUSE.org.html

2.6.31-bfs221-smp
Concurrency Level: 100
Time taken for tests: 43.556 seconds
Complete requests: 500000
Failed requests: 0
Write errors: 0
Total transferred: 7158558404 bytes
HTML transferred: 7027047358 bytes
Requests per second: 11479.50 [#/sec] (mean)
Time per request: 8.711 [ms] (mean)
Time per request: 0.087 [ms] (mean, across all concurrent requests)
Transfer rate: 160501.38 [Kbytes/sec] received

2.6.32-tip-smp NO_NEW_FAIR_SLEEPERS
Concurrency Level: 100
Time taken for tests: 42.834 seconds
Complete requests: 500000
Failed requests: 0
Write errors: 0
Total transferred: 7158429480 bytes
HTML transferred: 7026921590 bytes
Requests per second: 11672.84 [#/sec] (mean)
Time per request: 8.567 [ms] (mean)
Time per request: 0.086 [ms] (mean, across all concurrent requests)
Transfer rate: 163201.63 [Kbytes/sec] received

2.6.32-tip-smp NEW_FAIR_SLEEPERS
Concurrency Level: 100
Time taken for tests: 68.221 seconds
Complete requests: 500000
Failed requests: 0
Write errors: 0
Total transferred: 7158357900 bytes
HTML transferred: 7026851325 bytes
Requests per second: 7329.12 [#/sec] (mean)
Time per request: 13.644 [ms] (mean)
Time per request: 0.136 [ms] (mean, across all concurrent requests)
Transfer rate: 102469.65 [Kbytes/sec] received

2.6.32-tip-smp NEW_FAIR_SLEEPERS + ab at nice -15
Concurrency Level: 100
Time taken for tests: 42.824 seconds
Complete requests: 500000
Failed requests: 0
Write errors: 0
Total transferred: 7158451988 bytes
HTML transferred: 7026943572 bytes
Requests per second: 11675.68 [#/sec] (mean)
Time per request: 8.565 [ms] (mean)
Time per request: 0.086 [ms] (mean, across all concurrent requests)
Transfer rate: 163241.78 [Kbytes/sec] received

taskset -c 2 /etc/init.d/apache2 restart
taskset -c 3 ab -n 500000 -c 100 http://localhost/openSUSE.org.html

2.6.31-bfs221-smp
Concurrency Level: 100
Time taken for tests: 86.590 seconds
Complete requests: 500000
Failed requests: 0
Write errors: 0
Total transferred: 7158000000 bytes
HTML transferred: 7026500000 bytes
Requests per second: 5774.37 [#/sec] (mean)
Time per request: 17.318 [ms] (mean)
Time per request: 0.173 [ms] (mean, across all concurrent requests)
Transfer rate: 80728.41 [Kbytes/sec] received

2.6.32-tip-smp
Concurrency Level: 100
Time taken for tests: 48.640 seconds
Complete requests: 500000
Failed requests: 0
Write errors: 0
Total transferred: 7158000000 bytes
HTML transferred: 7026500000 bytes
Requests per second: 10279.71 [#/sec] (mean)
Time per request: 9.728 [ms] (mean)
Time per request: 0.097 [ms] (mean, across all concurrent requests)
Transfer rate: 143715.15 [Kbytes/sec] received



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