blktrace and dm devices?

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* blktrace and dm devices?
@ 2008-10-30 13:56 Martin Peschke
  2008-10-30 13:59 ` Jens Axboe
  0 siblings, 1 reply; 2+ messages in thread
From: Martin Peschke @ 2008-10-30 13:56 UTC (permalink / raw)
  To: linux-btrace

Hi,

I have noticed that I get C traces but no D traces for device mapper
devices. Is blktrace supposed to handle dm devices as well?

Thanks,
Martin


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: blktrace and dm devices?
  2008-10-30 13:56 blktrace and dm devices? Martin Peschke
@ 2008-10-30 13:59 ` Jens Axboe
  0 siblings, 0 replies; 2+ messages in thread
From: Jens Axboe @ 2008-10-30 13:59 UTC (permalink / raw)
  To: linux-btrace

On Thu, Oct 30 2008, Martin Peschke wrote:
> Hi,
> 
> I have noticed that I get C traces but no D traces for device mapper
> devices. Is blktrace supposed to handle dm devices as well?

The dispatch event is associated with request dispatching, which dm/md
does not do. You should get redirect events, telling you when the IO is
being redirected to the bottom device. Or split events.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 2+ messages in thread

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2008-10-30 13:56 blktrace and dm devices? Martin Peschke
2008-10-30 13:59 ` Jens Axboe

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