Re: [uml-devel] [PATCH] host context switch reduction

["roland" <for_spam@gmx.de>]

> If someone think this patch is really useful for 2.6 I can make the
> port.

for my personal opinion, every attempt to improve the performance of uml is useful.
:)

the question is:
is the "real world" performance benefit, uml get`s from this patch worth taking your time and is it implemented in a way, so that
uml maintainers are happy with that ?
i cannot really estimate, what performance benefits your patch brings to uml in detail, but what i have seen so far, this seems
quite worth doing the work.  reducing context switches by 1/3 is a LOT, imho - and reducing the execution time of the getpid-loop to
nearly the half is quite impressive.

are there any "con`s" that argue for that work _NOT_ being done ?

i would be a happy tester of a patch for 2.6 :)

regards
roland


----- Original Message ----- 
From: "Laurent Vivier" <LaurentVivier@wanadoo.fr>
To: "roland" <for_spam@gmx.de>
Cc: <user-mode-linux-devel@lists.sourceforge.net>
Sent: Tuesday, May 18, 2004 12:00 AM
Subject: Re: [uml-devel] [PATCH] host context switch reduction


> Hi,
>
> find hereunder the measurements I sent to Jeff.
>
> If someone think this patch is really useful for 2.6 I can make the
> port.
>
> Regards,
> Laurent
> Please CC: me, as I'm not in the mailing list.
>
> Le lun 17/05/2004 à 22:08, roland a écrit :
> > hi !
> > has this / will this be ported to 2.6 ?
> > have there been made further performance comparisons ?
> > regards
> > roland
> >
> >
> > >Well, we just looked at the context switches. We started 3 UMLs which
> > >were doing a make world for xfree. Without patches the number of
> > >context switches per second was around 60k, with the patch it was around
> > >40k - so it's noticeable, at least from the cs.
> > >Sven
> >
> > ----- Original Message ----- 
> > From: "Jeff Dike" <jdike@addtoit.com>
> > To: <user-mode-linux-devel@lists.sourceforge.net>
> > Sent: Sunday, February 29, 2004 6:35 AM
> > Subject: [uml-devel] [PATCH] host context switch reduction
> >
> >
> > > The patches below are from Laurent Vivier who didn't make them public.  They
> > > add a new feature to ptrace on the host which cuts down on the number of
> > > context switches needed for a UML system call, plus makes UML use it.
> > >
> > > There's some interest in this, so I'm putting it out as-is.  I haven't played
> > > with it.
> > >
> > > Laurent did some performance testing and found ~40% speedup on a getpid
> > > loop, and a 3.5% speedup on a kernel build.
> > >
> > > Jeff
> > >
> > >
>



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