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From: Ingo Molnar <mingo@elte.hu>
To: Darren Hart <dvhltc@us.ibm.com>
Cc: "Sébastien Dugué" <sebastien.dugue@bull.net>,
	"Lee Revell" <rlrevell@joe-job.com>,
	lkml <linux-kernel@vger.kernel.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Mike Galbraith" <efault@gmx.de>,
	"Steven Rostedt" <rostedt@goodmis.org>,
	"Florian Schmidt" <mista.tapas@gmx.net>
Subject: Re: rt20 scheduling latency testcase and failure data
Date: Thu, 18 May 2006 13:24:35 +0200	[thread overview]
Message-ID: <20060518112435.GA10463@elte.hu> (raw)
In-Reply-To: <200605180214.05690.dvhltc@us.ibm.com>


* Darren Hart <dvhltc@us.ibm.com> wrote:

> yet to see a missed period with the version of the program.  While 
> getting to this point, I did see some things that concerned me:
> 
> sched_la-4856  3D... 4083us!: math_state_restore (device_not_available)
> sched_la-4856  3D... 16033us : smp_apic_timer_interrupt (4b3b98e8 0 0)
> 
> Am I reading that right?  12ms to complete math_state_restore()?  What 
> does "device_not_available" mean here?

no - the kernel returned to userspace after doing the 
math_state_restore, and the next thing you saw is the timer IRQ. The 
tracer traces function entries, but not function exits.

> Here are some other similar traces:
> 
> sched_la-5008  2D... 4104us!: math_state_restore (device_not_available)
> sched_la-5008  2.... 4992us > sys_clock_gettime (00000001 b7fc8378 0000007b)

same here: we returned to userspace after FPU restore, and the next 
thing was a sys_clock_gettime() syscall ~800 usecs later.

	Ingo

  reply	other threads:[~2006-05-18 11:24 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-05-13  2:24 rt20 scheduling latency testcase and failure data Darren Hart
2006-05-13  9:20 ` Florian Paul Schmidt
2006-05-13 11:55   ` Mike Galbraith
2006-05-13 15:39     ` Steven Rostedt
2006-05-13 16:36       ` Mike Galbraith
2006-05-15  8:04       ` Ingo Molnar
2006-05-13 18:06   ` Darren Hart
2006-05-13 18:21     ` Lee Revell
2006-05-13 23:01       ` Darren Hart
2006-05-14  3:46         ` Mike Galbraith
2006-05-14  5:48           ` Mike Galbraith
2006-05-14  7:04             ` Darren Hart
2006-05-14  7:38               ` Mike Galbraith
2006-05-15  8:13         ` Ingo Molnar
2006-05-16  1:30           ` Darren Hart
2006-05-16  7:22             ` Sébastien Dugué
2006-05-18  9:14               ` Darren Hart
2006-05-18 11:24                 ` Ingo Molnar [this message]
2006-05-18  8:44             ` Sébastien Dugué
2006-05-18  8:47               ` Ingo Molnar
2006-05-18  8:58                 ` Sébastien Dugué
2006-05-18  8:56                   ` Ingo Molnar
2006-05-18  9:18                     ` Sébastien Dugué
2006-05-18  9:38                   ` Darren Hart
2006-05-18  9:58                     ` Sébastien Dugué
2006-05-19  5:48                     ` Mike Galbraith
2006-05-19  5:58                       ` Mike Galbraith
2006-05-15  5:43     ` Mike Galbraith
2006-05-15 16:52       ` Lee Revell
2006-05-15 11:20     ` Sébastien Dugué
2006-05-15 21:49       ` Darren Hart
2006-05-15 11:15 ` Sébastien Dugué
2006-05-15 14:34   ` Darren Hart

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