From: Stephen Flowers <sflowers1@gmail.com>
To: William Mills <wmills@ti.com>,
Bruce Ashfield <bruce.ashfield@windriver.com>,
yocto@yoctoproject.org, meta-ti@yoctoproject.org
Subject: Re: Yocto Realtime tests on beaglebone black
Date: Thu, 12 Feb 2015 22:05:10 +0000 [thread overview]
Message-ID: <54DD2396.4000909@gmail.com> (raw)
In-Reply-To: <54DBF55D.3020001@ti.com>
So I ran cyclictest with an idle system and loaded with multiple
instances of cat /dev/zero > /dev/null &
#cyclictest -a 0 -p 99 -m -n -l 100000 -q
I ran this command as shown by Toyoka at the 2014 Linuxcon Japan
[http://events.linuxfoundation.org/sites/events/files/slides/toyooka_LCJ2014_v10.pdf]
to compare against his results for the BBB. I also threw in xenomai
with kernel 3.8 for comparison. For the standard kernel HR timers were
disabled.
[idle]
preempt_rt: min 12 avg: 20 max: 59
standard: min: 8005 avg: 309985955 max: 619963985
xenomai: min: 8 avg: 16: max 803
[loaded]
preempt_rt: min 16 avg: 21 max: 47
standard: min: 15059 avg: 67769851 max: 135530885
xenomai: min: 10 avg: 15: max 839
Actually the preempt_rt results tie up pretty well with Toyooka above,
leading me to conclude theres something off in my code that could be
optimised - what do you guys think.
Also, I ran a test with preempt_rt at 100Hz and there was maybe 10%
improvement in latency.
Steve
On 12/02/2015 00:35, William Mills wrote:
> + meta-ti
> Please keep meta-ti in the loop.
>
> [Sorry for the shorting. Thunderbird keep locking up when I tried
> replay all in plain text to this message.]
>
> ~ 15-02-11, Stephen Flowers wrote:
> > Thanks for your input. Here are results of 1000 samples over a
> > 10 second period:
> >
> > Interrupt response (microseconds)
> > standard: min: 81, max:118, average: 84
> > rt: min: 224, max: 289, average: 231
> >
> >Will share the .config later once I get on that machine.
>
> Steve I agree the numbers look strange.
> There may well be something funny for RT going on for BBB.
> TI is just starting to look into RT for BBB.
>
> I would like to see the cyclictest results under heavy system load for
> standard and RT kernels. The whole point of RT is to limit the max
> latency when the system is doing *anything*.
>
> I am not surprised that the standard kernel has good latency when idle.
> As you add load (filessystem is usually a good load) you should see
> that max goes up a lot.
>
> Also, as Bruce says, some degradation of min and average and also
> general system throughput is expected for RT. That is the trade-off.
> I still think the number you are getting for RT seem high but I don't
> know what your test is doing in detail. (I did read your explanation.)
> cyclictest should give us a standard baseline.
>
>
> On 02/11/2015 10:25 AM, Bruce Ashfield wrote:
>> On 15-02-11 03:50 AM, Stephen Flowers wrote:
>>>
>>> my bad, here is the patch set.
>>> As for load, only system idle load for the results I posted previously.
>>> Will run some cyclic test next.
>>
>> One thing that did jump out was the difference in config_hz, you
>> are taking a lot more ticks in the preempt-rt configuration. If
>> you run both at the same hz, or with no_hz enabled, it would be
>> interesting to see if there's a difference.
>>
>> Bruce
WARNING: multiple messages have this Message-ID (diff)
From: Stephen Flowers <sflowers1@gmail.com>
To: William Mills <wmills@ti.com>,
Bruce Ashfield <bruce.ashfield@windriver.com>,
yocto@yoctoproject.org, meta-ti@yoctoproject.org
Subject: Re: [yocto] Yocto Realtime tests on beaglebone black
Date: Thu, 12 Feb 2015 22:05:10 +0000 [thread overview]
Message-ID: <54DD2396.4000909@gmail.com> (raw)
In-Reply-To: <54DBF55D.3020001@ti.com>
So I ran cyclictest with an idle system and loaded with multiple
instances of cat /dev/zero > /dev/null &
#cyclictest -a 0 -p 99 -m -n -l 100000 -q
I ran this command as shown by Toyoka at the 2014 Linuxcon Japan
[http://events.linuxfoundation.org/sites/events/files/slides/toyooka_LCJ2014_v10.pdf]
to compare against his results for the BBB. I also threw in xenomai
with kernel 3.8 for comparison. For the standard kernel HR timers were
disabled.
[idle]
preempt_rt: min 12 avg: 20 max: 59
standard: min: 8005 avg: 309985955 max: 619963985
xenomai: min: 8 avg: 16: max 803
[loaded]
preempt_rt: min 16 avg: 21 max: 47
standard: min: 15059 avg: 67769851 max: 135530885
xenomai: min: 10 avg: 15: max 839
Actually the preempt_rt results tie up pretty well with Toyooka above,
leading me to conclude theres something off in my code that could be
optimised - what do you guys think.
Also, I ran a test with preempt_rt at 100Hz and there was maybe 10%
improvement in latency.
Steve
On 12/02/2015 00:35, William Mills wrote:
> + meta-ti
> Please keep meta-ti in the loop.
>
> [Sorry for the shorting. Thunderbird keep locking up when I tried
> replay all in plain text to this message.]
>
> ~ 15-02-11, Stephen Flowers wrote:
> > Thanks for your input. Here are results of 1000 samples over a
> > 10 second period:
> >
> > Interrupt response (microseconds)
> > standard: min: 81, max:118, average: 84
> > rt: min: 224, max: 289, average: 231
> >
> >Will share the .config later once I get on that machine.
>
> Steve I agree the numbers look strange.
> There may well be something funny for RT going on for BBB.
> TI is just starting to look into RT for BBB.
>
> I would like to see the cyclictest results under heavy system load for
> standard and RT kernels. The whole point of RT is to limit the max
> latency when the system is doing *anything*.
>
> I am not surprised that the standard kernel has good latency when idle.
> As you add load (filessystem is usually a good load) you should see
> that max goes up a lot.
>
> Also, as Bruce says, some degradation of min and average and also
> general system throughput is expected for RT. That is the trade-off.
> I still think the number you are getting for RT seem high but I don't
> know what your test is doing in detail. (I did read your explanation.)
> cyclictest should give us a standard baseline.
>
>
> On 02/11/2015 10:25 AM, Bruce Ashfield wrote:
>> On 15-02-11 03:50 AM, Stephen Flowers wrote:
>>>
>>> my bad, here is the patch set.
>>> As for load, only system idle load for the results I posted previously.
>>> Will run some cyclic test next.
>>
>> One thing that did jump out was the difference in config_hz, you
>> are taking a lot more ticks in the preempt-rt configuration. If
>> you run both at the same hz, or with no_hz enabled, it would be
>> interesting to see if there's a difference.
>>
>> Bruce
next prev parent reply other threads:[~2015-02-12 22:05 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-10 13:06 Yocto Realtime tests on beaglebone black Stephen Flowers
2015-02-10 14:16 ` Bruce Ashfield
2015-02-10 14:39 ` Stephen Flowers
2015-02-10 14:40 ` Bruce Ashfield
2015-02-10 14:43 ` Stephen Flowers
2015-02-10 22:23 ` Stephen Flowers
2015-02-11 4:41 ` Bruce Ashfield
2015-02-11 8:50 ` Stephen Flowers
2015-02-11 15:25 ` Bruce Ashfield
2015-02-12 0:35 ` William Mills
2015-02-12 0:35 ` [yocto] " William Mills
2015-02-12 3:50 ` Bruce Ashfield
2015-02-12 3:50 ` [yocto] " Bruce Ashfield
2015-02-12 22:05 ` Stephen Flowers [this message]
2015-02-12 22:05 ` Stephen Flowers
2015-02-13 0:20 ` William Mills
2015-02-13 0:20 ` [yocto] " William Mills
2015-02-13 5:08 ` Bruce Ashfield
2015-02-13 5:08 ` [yocto] " Bruce Ashfield
2015-02-17 22:57 ` Stephen Flowers
2015-02-17 22:57 ` [yocto] " Stephen Flowers
2015-02-18 14:57 ` Bruce Ashfield
2015-02-18 14:57 ` [yocto] " Bruce Ashfield
2015-02-18 15:19 ` Stephen Flowers
2015-02-18 15:19 ` [yocto] " Stephen Flowers
2015-02-18 18:43 ` Bruce Ashfield
2015-02-18 18:43 ` [yocto] " Bruce Ashfield
2015-04-13 13:24 ` Trevor Woerner
2015-04-13 13:24 ` [yocto] " Trevor Woerner
2015-04-13 13:37 ` Stephen Flowers
2015-04-13 13:38 ` [yocto] " Stephen Flowers
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