Re: [Xenomai-core] Fwd: problem in pthread_mutex_lock/unlock

[Nero Fernandez <grimlynch@domain.hid>]

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Yes, the measurements are on no-load scenarios.
I will try to repeat my measurements with system-loads as you suggest.

Following is the cpu-info of my board:
----------------------------------------------------------
Processor       : ARM926EJ-S rev 5 (v5l)
BogoMIPS        : 131.48
Features        : swp half fastmult edsp java
CPU implementer : 0x41
CPU architecture: 5TEJ
CPU variant     : 0x0
CPU part        : 0x926
CPU revision    : 5
Cache type      : write-back
Cache clean     : cp15 c7 ops
Cache lockdown  : format C
Cache format    : Harvard
I size          : 16384
I assoc         : 4
I line length   : 32
I sets          : 128
D size          : 16384
D assoc         : 4
D line length   : 32
D sets          : 128
----------------------------------------------------------

On Thu, Jun 24, 2010 at 5:20 PM, Gilles Chanteperdrix <
gilles.chanteperdrix@xenomai.org> wrote:

> Nero Fernandez wrote:
> > Thanks for your response, Philippe.
> >
> > The concerns while the carrying out my experiments were to:
> >
> >  - compare xenomai co-kernel overheads (timer and context switch
> latencies)
> >    in xenomai-space vs similar native-linux overheads. These are
> > presented in
> >    the first two sheets.
>
> On what ARM system do you get these latency figures? I really doubt the
> linux kernel has a bounded latency under 35us. Because:
> - the preempt_rt people, which work on getting a bounded latency get
> something around 200us on AT91, an ARM9;
> - there would be no reason of the preempt_rt effort if the linux kernel
> interrupt latency was already bounded.
>
> So, I take it that you do your measurement without generating a load. We
> do our measurements using the latency test, while generating a load for
> several hours. And on the average ARM, we usually get an interrupt
> latency around 50us.
>
> Please add some load on the system, and do the measurments again. The
> best source of load we have found so far is to load the LTP testsuite
> while running the latency test.
>
> If you tell me what ARM SOC, or at least what ARM architecture revision
> you use (the ARM920T core is an armv4, and the ARM926EJS is an armv5, so
> ARM 9 does not tell us much), I can provide you with the root filesystem
> we use for our tests.
>
> --
>                                             Gilles.
>

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