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From: Arnout Vandecappelle <arnout@mind.be>
To: xenomai@xenomai.org
Subject: [Xenomai] CPU occupation without context switches?
Date: Tue, 22 May 2012 18:09:09 +0200	[thread overview]
Message-ID: <4FBBBA25.5010308@mind.be> (raw)

  Hoi,

  After a few minutes of running my application, I see this:

# cat /proc/xenomai/stat
CPU  PID    MSW        CSW        PF    STAT       %CPU  NAME
   1  828    22         65         0     00300182    9.8  bench_RTnet_scope_thread_loop
   1  839    2          46627538   0     00300186   53.8  bench_RTnet
...

  i.e. the bench_RTnet_scope_thread_loop takes 10% CPU but no
context switches.  How is this possible?  I've looked at the
source code and can't find an explanation: when the exectime
accounting is updated, the csw is incremented as well (in
__xnpod_schedule()).

  I'm asking because I can't find a reason why this thread should
occupy 10% of the CPU, so I'm wondering if there's something wrong
with the accounting instead.

  BTW this is on Xenomai 2.5.6, on an SMP x86 with affinity=0x01.

  Regards,
  Arnout

-- 
Arnout Vandecappelle                               arnout at mind be
Senior Embedded Software Architect                 +32-16-286540
Essensium/Mind                                     http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium                BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F



             reply	other threads:[~2012-05-22 16:09 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-22 16:09 Arnout Vandecappelle [this message]
2012-05-22 18:17 ` [Xenomai] CPU occupation without context switches? Gilles Chanteperdrix
2012-05-22 19:44 ` Philippe Gerum
2012-05-23  8:31   ` Arnout Vandecappelle
2012-05-23  8:45     ` Philippe Gerum
2012-05-23  9:37       ` Philippe Gerum

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