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

[Peter Maloney <peter.maloney@xxxxxxxxxxxxxxxxxxxx>]

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?


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