Re: [Bug #11308] tbench regression on each kernel release from 2.6.22 -> 2.6.28

Mike Galbraith
2008-09-13T11:44:47Z

On Fri, 2008-09-12 at 17:05 -0500, Christoph Lameter wrote:
> Rafael J. Wysocki wrote:
> > This message has been generated automatically as a part of a report
> > of recent regressions.
> >
> > The following bug entry is on the current list of known regressions
> > from 2.6.26. Please verify if it still should be listed and let me know
> > (either way).
> >
> >
> > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=11308
> > Subject : tbench regression on each kernel release from 2.6.22 -&gt; 2.6.28
> > Submitter : Christoph Lameter <cl-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
> > Date : 2008-08-11 18:36 (33 days old)
> > References : http://marc.info/?l=linux-kernel&m=121847986119495&w=4
> >
> >
> >
>
> tbench
>
> 2.6.27-rc6 2760 MB/sec
> 2.6.22 3235.47 MB/sec

Numbers from my Q6600 Aldi supermarket box (hm, your box is from different shelf)

tbench -t 60 4 localhost followed by 4 60s netperf TCP_RR pairs, each pair
jabbering on a separate port and affine to a separate CPU. Configs are
as close as I can make them, all kernels built and tested today by
identical userland.

2.6.22.19
Throughput 1136.02 MB/sec 4 procs

16384 87380 1 1 60.01 94179.12
16384 87380 1 1 60.01 88780.61
16384 87380 1 1 60.01 91057.72
16384 87380 1 1 60.01 94242.16

2.6.22.19-cfs-v24.1 (identical config)
Throughput 1126.79 MB/sec 4 procs

16384 87380 1 1 60.00 88809.14
16384 87380 1 1 60.00 89971.25
16384 87380 1 1 60.01 89452.91
16384 87380 1 1 60.01 89478.63

2.6.23.17
Throughput 1073.2 MB/sec 4 procs

16384 87380 1 1 60.00 83635.61
16384 87380 1 1 60.00 82754.36
16384 87380 1 1 60.00 84594.59
16384 87380 1 1 60.00 82995.81

2.6.23.17-cfs-v24.1 (identical config)
Throughput 1145.28 MB/sec 4 procs

16384 87380 1 1 60.00 90278.55
16384 87380 1 1 60.01 90579.31
16384 87380 1 1 60.01 89412.14
16384 87380 1 1 60.00 90270.97

2.6.24.7
Throughput 1119.28 MB/sec 4 procs

16384 87380 1 1 60.00 84092.78
16384 87380 1 1 60.00 84120.68
16384 87380 1 1 60.00 84076.73
16384 87380 1 1 60.00 83995.07

2.6.25.17
Throughput 1113.82 MB/sec 4 procs

16384 87380 1 1 60.00 84629.98
16384 87380 1 1 60.00 84776.38
16384 87380 1 1 60.00 84356.49
16384 87380 1 1 60.00 84469.71

2.6.26.5
Throughput 1095.26 MB/sec 4 procs

16384 87380 1 1 60.00 84481.11
16384 87380 1 1 60.00 84604.38
16384 87380 1 1 60.01 86526.84
16384 87380 1 1 60.01 84478.01

2.6.27-rc6
Throughput 1037.98 MB/sec 4 procs

16384 87380 1 1 60.00 80293.80
16384 87380 1 1 60.00 80266.60
16384 87380 1 1 60.00 80394.83
16384 87380 1 1 60.01 80397.27

I spent two weeks chasing various and sundry netperf numbers recently,
only learning in the process that netperf is _utterly immune_ to
bisection. Tbench numbers don't look promising for bisection from here.

Note to quixotic self: destroy log immediately lest you be tempted.

-Mike