linux-kernel - Re: [PATCH 10] PM: Measure suspend and resume times for individual devices (was: Re: [PATCH 2/6] PM: Asynchronous resume of devices)

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Message-ID: <Pine.LNX.4.44L0.0908311006490.10295-100000@iolanthe.rowland.org>
Date:	Mon, 31 Aug 2009 10:09:54 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
cc:	linux-pm <linux-pm@...ts.linux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>, Len Brown <lenb@...nel.org>,
	Pavel Machek <pavel@....cz>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Arjan van de Ven <arjan@...radead.org>,
	Zhang Rui <rui.zhang@...el.com>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Linux PCI <linux-pci@...r.kernel.org>
Subject: Re: [PATCH 10] PM: Measure suspend and resume times for individual
 devices (was: Re: [PATCH 2/6] PM: Asynchronous resume of devices)

On Sun, 30 Aug 2009, Rafael J. Wysocki wrote:

> > > For testing purposes it would be nice to have a one-line summary for
> > > each device containing a thread ID, start timestamp, end timestamp, and
> > > elapsed time.  With that information you could evaluate the amount of
> > > parallelism and determine where the bottlenecks are.  It would give a
> > > much more detailed picture of the entire process than the total time of
> > > your recent patch 9.
> > 
> > Of course it would.  I think I'll implement it.
> 
> OK, below is a patch for that.  It only prints the time elapsed, because the
> timestamps themselves can be obtained from the usual kernel timestamping.

Does that include the start timestamps?  I don't see them anywhere in
the patch.  Without the start timestamps we have no way to know how
much time was spent waiting for dpm_list_mtx or other resources as
opposed to actually carrying out the operation.

Alan Stern


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