Hello Jan,
On 18.07.19 18:04, Jan Beulich wrote:
On 18.07.2019 16:12, Andrii Anisov wrote:
The scenario is quite trivial: some vcpu uptdating its runstate values
(e.g. context switching) while those values are being read by a guest using
other vcpu.
Well, that's (afaia) not an intended usage
On 18.07.2019 16:12, Andrii Anisov wrote:
> On 18.07.19 14:10, Jan Beulich wrote:
>> A concrete scenario where update_runstate_area() and vcpu_runstate_change()
>> can actually race would be very worthwhile to point out here. In particular
>> on Arm I'm not (yet?) seeing how this could happen.
>
>
Hello Jan,
On 18.07.19 14:10, Jan Beulich wrote:
Considering the value of XEN_RUNSTATE_UPDATE it must be a rather rare race
anyway, I would guess.
I'm not sure about the exact rate of the race, but with following prints:
diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 25f6ab3
Hello Jan,
On 18.07.19 14:10, Jan Beulich wrote:
A concrete scenario where update_runstate_area() and vcpu_runstate_change()
can actually race would be very worthwhile to point out here. In particular
on Arm I'm not (yet?) seeing how this could happen.
The scenario is quite trivial: some vcpu
On 18.07.2019 11:54, Andrii Anisov wrote:
> Using XEN_RUNSTATE_UPDATE mask during the process of copying runstate
> values to guest causes runstate entry time to be eventually considered
> negative on a calculation of the time delta. So the XEN_RUNSTATE_UPDATE
> should be masked out during the calc
Hello George,
The patch was also CC'ed to you, but I got:
"554 esa1.hc3370-68.iphmx.com You are being rejected because your senderbase score
is below our accepted policy."
from your server.
ps. I hope I'm not bothering you too much.
On 18.07.19 12:54, Andrii Anisov wrote:
From: Andrii Aniso
From: Andrii Anisov
Using XEN_RUNSTATE_UPDATE mask during the process of copying runstate
values to guest causes runstate entry time to be eventually considered
negative on a calculation of the time delta. So the XEN_RUNSTATE_UPDATE
should be masked out during the calculation of the time spent in
