From: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>
To: Marcelo Tosatti <marcelo-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>
Cc: kvm-devel
<kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>,
Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
Subject: Re: [RFC] VMX CR3 cache
Date: Mon, 28 Jan 2008 18:37:08 +0100 [thread overview]
Message-ID: <20080128173707.GB22487@elte.hu> (raw)
In-Reply-To: <20080128173530.GA4956@dmt>
* Marcelo Tosatti <marcelo-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org> wrote:
> > when i did the testing then i was able to get zero VM exits in the
> > lat_ctx hotpath and get the same performance as on native. The above
> > numbers you got suggest that this is not the case. (your lat_ctx
> > numbers on native are probably around 1 usec, right?)
>
> Actually, native is around 5usec:
>
> # bin/x86_64-linux-gnu/lat_ctx -N 10 2
>
> "size=0k ovr=1.09
> 2 5.21
>
> So it does get pretty close to native, but the problem is that its
> difficult to see improvements on macrobenchmarks (even hackbench which
> remotely resembles a real scenario is not improving).
try running your shell on one CPU:
taskset -p 1 $$
that should give you the 'raw' single-CPU context switch results.
Ingo
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next prev parent reply other threads:[~2008-01-28 17:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-28 16:04 [RFC] VMX CR3 cache Marcelo Tosatti
2008-01-28 17:17 ` Ingo Molnar
[not found] ` <20080128171734.GA19705-X9Un+BFzKDI@public.gmane.org>
2008-01-28 17:35 ` Marcelo Tosatti
2008-01-28 17:37 ` Ingo Molnar [this message]
[not found] ` <20080128173707.GB22487-X9Un+BFzKDI@public.gmane.org>
2008-01-28 18:17 ` Marcelo Tosatti
2008-01-28 17:23 ` Avi Kivity
2008-01-29 8:54 ` Gerd Hoffmann
[not found] ` <479EE9C3.8000007-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2008-01-29 10:28 ` Gerd Hoffmann
[not found] ` <479EFFB0.1000700-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2008-01-29 10:32 ` Gerd Hoffmann
2008-01-29 12:33 ` Marcelo Tosatti
2008-01-30 8:26 ` Gerd Hoffmann
[not found] ` <47A034CD.9010708-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2008-01-30 9:18 ` Gerd Hoffmann
[not found] ` <47A040E3.7000207-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2008-01-30 10:10 ` Avi Kivity
[not found] ` <47A04D1C.4090505-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2008-01-30 12:05 ` Gerd Hoffmann
2008-01-30 13:25 ` Marcelo Tosatti
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