linux-kernel - Re: 2.6.19-rc6-rt5

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Message-ID: <a0580c510611231243x318f3cbanc8fa2cbbedcec060@mail.gmail.com>
Date:	Thu, 23 Nov 2006 16:43:01 -0400
From:	"Eduardo Valentin" <edubezval@...il.com>
To:	"Robert Schwebel" <r.schwebel@...gutronix.de>
Cc:	"Ingo Molnar" <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: 2.6.19-rc6-rt5

Hello Robert and Ingo,


   I'm beginning to play with -rt patches. I started by using the
2.6.19-rc6-rt5, after reading the rt-wiki
(http://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO). I applied the
last two compile corrections patches. However, I got a similar problem
as reported by Robert:

2.6.19-rc6:
T: 0 ( 4861) P:80 I:   10000 C:   10000 Min:    2592 Act:    4878 Avg:
   6137 Max:   10652
2.6.19-rc6-rt5:
T: 0 ( 3661) P:80 I:   10000 C:   10000 Min:     828 Act:    1698 Avg:
   3291 Max:    7171
   These results are quite different from what is reported at the wiki.

   I'm also attaching my .config and here is a description of my cpu:
cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      : Intel(R) Xeon(TM) CPU 3.40GHz
stepping        : 1
cpu MHz         : 3391.745
cache size      : 1024 KB
physical id     : 0
siblings        : 1
core id         : 0
cpu cores       : 1
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 3
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx
lm constant_tsc up pni monitor ds_cpl est cid cx16 xtpr
bogomips        : 6788.16



BR,


Eduardo Valentin

On 11/22/06, Robert Schwebel <r.schwebel@...gutronix.de> wrote:
> On Mon, Nov 20, 2006 at 11:02:30PM +0100, Ingo Molnar wrote:
> > i've released the 2.6.19-rc6-rt5 tree, which can be downloaded from the
> > usual place:
>
> [...]
>
> > as usual, bugreports, fixes and suggestions are welcome,
>
> I have problems runinng cyclictest on the more recent -rt kernels. A
> similar problem I reported recently on a Pentium M / ICH6 Dell box is
> solved by using the acpi_pm timer.
>
> The problematic box is a 700 MHz Celeron (Coppermine) which doesn't have
> ACPI.
>
> The last kernel that run with sane cyclictest results was 2.6.18-rt6:
>
> - root@...chkiste:~/cyclictest-v0.11 ./cyclictest -n -t 4 -p 90 -l 10000
>   0.13 0.10 0.13 1/52 2721
>
>   T: 0 ( 2718) P:90 I:    1000 C:   10000 Min:      14 Act:      47 Avg:      52 Max:     170
>   T: 1 ( 2719) P:89 I:    1500 C:    6667 Min:      16 Act:      22 Avg:      45 Max:     138
>   T: 2 ( 2720) P:88 I:    2000 C:    5001 Min:      16 Act:      35 Avg:      44 Max:     101
>   T: 3 ( 2721) P:87 I:    2500 C:    4001 Min:      14 Act:      28 Avg:      38 Max:     114
>
> The following numbers have been taken on 2.6.19-rc6-rt5, the effect is there
> since 2.6.18-rt7.
>
> - "cyclictest -n -p 90 -t 4" is just "running upwards".
>
>   root@...chkiste:~/cyclictest-v0.11 ./cyclictest -n -p 90 -t 4 -l 1000
>   0.00 0.00 0.00 1/54 2843
>
>   T: 0 ( 2840) P:90 I:    1000 C:    1000 Min:    7294 Act: 3008486 Avg: 1508852 Max: 3008486
>   T: 1 ( 2841) P:89 I:    1500 C:    1000 Min:    7195 Act: 2508885 Avg: 1258994 Max: 2508885
>   T: 2 ( 2842) P:88 I:    2000 C:    1000 Min:    7188 Act: 2009375 Avg: 1009235 Max: 2009375
>   T: 3 ( 2843) P:87 I:    2500 C:    1000 Min:    7184 Act: 1509868 Avg:  759479 Max: 1509868
>
> - Using a relative timer (-r), I get huge latencies:
>
>   root@...chkiste:~/cyclictest-v0.11 ./cyclictest -n -p 90 -t 4 -r -l 1000
>   0.00 0.00 0.00 1/56 2838
>
>   T: 0 ( 2835) P:90 I:    1000 C:    1000 Min:     742 Act:    6937 Avg:    6952 Max:    9214
>   T: 1 ( 2836) P:89 I:    1500 C:    1000 Min:     244 Act:    6424 Avg:    6454 Max:    8718
>   T: 2 ( 2837) P:88 I:    2000 C:     999 Min:    1288 Act:    5910 Avg:    5962 Max:    8216
>   T: 3 ( 2838) P:87 I:    2500 C:     999 Min:     778 Act:    5409 Avg:    5462 Max:    7713
>
> This is with "lapic lapictimer" on the kernel commandline.
>
> The system has chosen "pit" as it's clocksource, switching to tsc or jiffies
> doesn't change anything.
>
> With 2.6.18-rt6 I've seen these lines in the dmesg output:
>
> Nov 22 12:05:24 krachkiste kernel: Time: tsc clocksource has been installed.
> Nov 22 12:05:24 krachkiste kernel: Event source pit disabled
> Nov 22 12:05:24 krachkiste kernel: Event source lapic configured with caps set: 08
> Nov 22 12:05:24 krachkiste kernel: hrtimers: Switched to high resolution mode CPU 0
>
> Especially the "Switched to high resolution mode" isn't there with the later
> kernels (high resolution timers is on in the config, dyntick is off).
>
> Robert
> --
>  Dipl.-Ing. Robert Schwebel | http://www.pengutronix.de
>  Pengutronix - Linux Solutions for Science and Industry
>    Handelsregister:  Amtsgericht Hildesheim, HRA 2686
>      Hannoversche Str. 2, 31134 Hildesheim, Germany
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>
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>


-- 
Eduardo Bezerra Valentin

Download attachment "config" of type "application/octet-stream" (54833 bytes)