2.6.23.1-rt9 (and others)

2.6.23.1-rt9 (and others)

[Steven Rostedt]

This is a special announcement for the latest -rt patches. This is
actually announcing more than one tree (pay close attention to the
differences between -rt7, -rt8 and -rt9).

  2.6.23.1-rt6

   - Removed BUG_ON in exit (Steven Rostedt and Daniel Walker)

   -  Turn RCU preempt boost on by default (Steven Rostedt)
      (for when RCU PREEMPT is enabled)

   - Fixes for PowerPC (Paul McKenney)


  2.6.23.1-rt7

   - Found that there's a flaw in the PowerPC patch so
     it was pulled from the tree.

  2.6.23.1-rt8

   - More aggressive RT Balancing (Gregory Haskins)

  2.6.23.1-rt9

   - RT balancing by CPU priorities (Gregory Haskins)


Now benchmarks against 2.6.23.1-rt7 -rt8 and -rt9 would be greatly
appreciated.  These three are all present in

  http://www.kernel.org/pub/linux/kernel/projects/rt/

Gregory and I have been having disagreements on how to solve RT task
balancing among CPUS. Although we shared ideas back and forth, and both
our methods have been greatly influenced by each other, the real answer
comes from actual numbers. So these three versions are posted for your
convenience to see which actually do the best. I would be happy to tell
Gregory he's right, if the numbers prove it.

Currently, what we do to test RT latencies is to run Thomas Gleixner's
cyclictest
(http://git.kernel.org/?p=linux/kernel/git/tglx/rt-tests.git;a=summary)
as well as hackbench, to see what the maximum latencies we get are.

Other tests are welcomed too.


to build a 2.6.23.1-rt7 tree, the following patches should be applied:

  http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.23.1.tar.bz2 
  http://www.kernel.org/pub/linux/kernel/projects/rt/patch-2.6.23.1-rt7.bz2

to build a 2.6.23.1-rt8 tree, the following patches should be applied:

  http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.23.1.tar.bz2 
  http://www.kernel.org/pub/linux/kernel/projects/rt/patch-2.6.23.1-rt8.bz2

to build a 2.6.23.1-rt9 tree, the following patches should be applied:

  http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.23.1.tar.bz2 
  http://www.kernel.org/pub/linux/kernel/projects/rt/patch-2.6.23.1-rt9.bz2


And like always, my RT version of Matt Mackall's ketchup will get this
for you nicely:

  http://people.redhat.com/srostedt/rt/tools/ketchup-0.9.8-rt1

The broken out patches are also available.

Thanks!

-- Steve

Re: 2.6.23.1-rt9 (and others)

[Steven Rostedt]

On Wed, 7 Nov 2007, Steven Rostedt wrote:

> This is a special announcement for the latest -rt patches. This is
> actually announcing more than one tree (pay close attention to the
> differences between -rt7, -rt8 and -rt9).
>

[...]

>   2.6.23.1-rt9
>
>    - RT balancing by CPU priorities (Gregory Haskins)

-rt9 has been found to break UP compilation, so -rt10 has been released
with the fix.

>
>
> Now benchmarks against 2.6.23.1-rt7 -rt8 and -rt9 would be greatly
> appreciated.  These three are all present in

So please compare -rt7, -rt8 and -rt10.

-- Steve

>
>   http://www.kernel.org/pub/linux/kernel/projects/rt/
>

Re: 2.6.23.1-rt9 (and others)

[Gregory Haskins]

>>> On Wed, Nov 7, 2007 at 10:41 AM, in message
<Pine.LNX.4.58.0711071040210.8572@gandalf.stny.rr.com>, Steven Rostedt
<rostedt@goodmis.org> wrote: 

> 
> So please compare -rt7, -rt8 and -rt10.

Here are my results from running:

sudo chrt -f 80 ./cyclictest -n -p 90 -t 8 -d 100 -i 100

with

while true; do make mrproper; make allmodconfig; make -j 128 > /dev/null; done
 on a plain kernel.org kernel

running in the background on an 8-way (4core x2) C2D Xeon 5335 system

23.1-rt7
---------------------------

  144.60 135.30 116.38 30/814 8184

  T: 0 ( 5990) P:90 I:100 C:11560415 Min:2 Act:  5 Avg: 4 Max:  83
  T: 1 ( 5991) P:89 I:200 C:5780208 Min: 2 Act:  5 Avg: 4 Max:  66
  T: 2 ( 5992) P:88 I:300 C:3853472 Min: 2 Act:  5 Avg: 5 Max:  89
  T: 3 ( 5993) P:87 I:400 C:2890104 Min: 2 Act:  6 Avg: 5 Max:  70
  T: 4 ( 5994) P:86 I:500 C:2312083 Min: 2 Act:  4 Avg: 5 Max:  91
  T: 5 ( 5995) P:85 I:600 C:1926736 Min: 2 Act:  5 Avg: 5 Max:  94
  T: 6 ( 5996) P:84 I:700 C:1651488 Min: 2 Act: 12 Avg: 5 Max: 115
  T: 7 ( 5997) P:83 I:800 C:1445052 Min: 2 Act:  6 Avg: 5 Max:  79

23.1-rt8
---------------------------
  119.95 106.56 107.98 37/811 18445

  T: 0 ( 5052) P:90 I:100 C:29592746 Min: 2 Act: 21 Avg: 4 Max:  78
  T: 1 ( 5053) P:89 I:200 C:14796374 Min: 2 Act:  6 Avg: 4 Max:  81
  T: 2 ( 5054) P:88 I:300 C:9864249 Min:  2 Act: 10 Avg: 4 Max:  88
  T: 3 ( 5055) P:87 I:400 C:7398187 Min:  2 Act:  6 Avg: 4 Max:  86
  T: 4 ( 5056) P:86 I:500 C:5918550 Min:  2 Act: 13 Avg: 9 Max:  69
  T: 5 ( 5057) P:85 I:600 C:4932125 Min:  2 Act: 11 Avg: 4 Max:  71
  T: 6 ( 5058) P:84 I:700 C:4227536 Min:  2 Act:  8 Avg: 5 Max:  65
  T: 7 ( 5059) P:83 I:800 C:3699094 Min:  2 Act:  4 Avg: 4 Max: 114

23.1-rt10
---------------------------
  143.39 123.49 117.92 22/791 5802

  T: 0 ( 5305) P:90 I:100 C:45332860 Min: 2 Act:  4 Avg: 4 Max: 89
  T: 1 ( 5306) P:89 I:200 C:22666431 Min: 2 Act:  3 Avg: 5 Max: 49
  T: 2 ( 5307) P:88 I:300 C:15110954 Min: 2 Act:  6 Avg: 5 Max: 76
  T: 3 ( 5308) P:87 I:400 C:11333216 Min: 2 Act:  7 Avg: 5 Max: 81
  T: 4 ( 5309) P:86 I:500 C:9066572 Min:  2 Act:  8 Avg: 5 Max: 57
  T: 5 ( 5310) P:85 I:600 C:7555477 Min:  2 Act:  8 Avg: 5 Max: 55
  T: 6 ( 5311) P:84 I:700 C:6476123 Min:  2 Act: 14 Avg: 6 Max: 73
  T: 7 ( 5312) P:83 I:800 C:5666608 Min:  2 Act:  5 Avg: 6 Max: 78

note that the rt10 image was running for a much longer duration than the other two...which generally will push the max higher.  I know in general if I let -rt7 go that long it will hit 120-150+.  This means these tests were biased towards -rt7 and -rt8 performing better, but they still came in with higher latencies.

I will officially test -rt11 next, tho in my small runs so far it looks great.

HTH

Regards,
-Greg