Re: [UDEV, PATCH] Add profiling support to Makefile

[Greg KH <greg@kroah.com>]

On Tue, Feb 15, 2005 at 10:12:56AM +0100, Kay Sievers wrote:
> On Tue, 2005-02-15 at 09:45 +0100, Michael Buesch wrote:
> >Quoting Greg KH <greg@kroah.com>:
> >> On Sun, Feb 13, 2005 at 05:16:51PM +0100, Michael Buesch wrote:
> >> > Hi,
> >> > 
> >> > This patch adds an option to the Makefile to enable
> >> > profiling. Profiling is only enabled, when not building
> >> > against klibc, as klibc lacks support for mcount().
> >> > 
> >> > Please apply. Thanks.
> >> 
> >> You forgot to update the documentation about this option, so I'll hold
> >> off till you redo that :)
> >
> >Oops. :O Here it is.
> >
> >> Also, what has profiling information helped you out with in udev?  Found
> >> anything interesting?  Or are you just using it for coverage analysis
> >> (which is a flawed thing, but that's another topic...)
> >
> >I did not do much testing, yet, because of missing time.
> >But I will do that.
> >My first testrun showed that the namedev matchrule function and the udevdb
> >are the slowest parts of the whole executable. So maybe there's some
> >optimization possible. But I'll look closer at it later.
> 
> The biggest part of it seems libsysfs. A replacement of the attribute
> reading functions with a simple open() gives ~20% speed increase for
> udevstart on my box.

As I doubt libsysfs will be fixed in this regard anytime soon, want to
add this to the tree?  A 20% speed increase for such a simple change is
a very good thing to have :)

thanks,

greg k-h


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