Re: [Xen-devel] xen-unstable, winxp32 very poor performance on AMD FX-8150, I bisected and changeset is 24770:7f79475d3de7

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

On 17/01/13 20:57, Pasi Kärkkäinen wrote:
> Hello,
>
> George: What do you think, should we add this bug to the Xen 4.3 status email 
> for tracking it?
> It's a serious HVM/winxp performance regression on AMD..
Hey Pasi -- thanks for bringing this thread to my attention.  I had 
noticed a performance impact on AMD boxen myself, but investigating it 
had kind of gotten buried in more urgent tasks.  Yes, I think we should 
track it.  I'll put it on the list.
 -George

> -- Pasi
>
> On Sat, Jan 12, 2013 at 04:25:47PM +0100, Peter Maloney wrote:
> > On 11/22/2012 07:54 PM, Peter Maloney wrote:
> > > On 11/13/2012 02:17 PM, Peter Maloney wrote:
> > > > On 2012-11-01 18:28, Andres Lagar-Cavilla wrote:
> > > > > On Nov 1, 2012, at 1:00 PM, Tim Deegan <tim@xxxxxxx> wrote:
> > > > >
> > > > > > Hi,
> > > > > >
> > > > > > At 14:59 +0100 on 22 Oct (1350917960), Tim Deegan wrote:
> > > > > > > At 19:21 +0200 on 20 Oct (1350760876), Peter Maloney wrote:
> > > > > > > > The change was 8 months ago
> > > > > > > >
> > > > > > > > changeset:   24770:7f79475d3de7
> > > > > > > > user:        Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>
> > > > > > > > date:        Fri Feb 10 16:07:07 2012 +0000
> > > > > > > > summary:     x86/mm: Make p2m lookups fully synchronized wrt modifications
> > > > > > [...]
> > > > > Not any immediate ideas without profiling.
> > > > >
> > > > > However, most callers of hvmemul_do_io pass a stub zero ram_gpa address. We 
> > > > > might be madly hitting the p2m locks for no reason there.
> > > > >
> > > > > How about the following patch, Peter, Tim?
> > > I tried the patch applied to xen-unstable 4.2.0-branched
> > > 528f0708b6db+ 4.2.0-branched
> > >
> > > It seemed the same. It was extremely slow with 7 vcpus, and with 2 vcpus
> > > it was slow, but fast enough that I could bother to log in and out
> > > during the test.
> > >
> > > Attached are logs generated with this command (using xm instead of xl):
> > > for i in {1..30}; do xm debug-keys d; xm dmesg -c; done >> nameoflog
> > >
> > > xenxp_xm_dmesg_-c_7cpus_idle.log
> > > xenxp_xm_dmesg_-c_7cpus_logintooslow.log
> > > xenxp_xm_dmesg_-c_7cpus_shutdown.log
> > > xenxp_xm_dmesg_-c_duringlogin.log
> > > xenxp_xm_dmesg_-c_idling_login_screen.log
> > >
> > > Also there is xenxp_dmesg.log which is output from hitting alt+sysrq+w
> > > and p in case it's relevant.
> > >
> > > BTW this time I am testing with kernel 3.6.7
> > I also tested 4.2.1 now, and it has the same problem. And after using it
> > for a while with windows 8 (playing games), I get the general feel that
> > it is laggier than with 4.1.3. And now I'm using 4.1.4 which is fast
> > like 4.1.3.
> >
> > So any ideas on how to fix this or gather more useful information?
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxx
> > http://lists.xen.org/xen-devel

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