On 07/12/2018 01:58 PM, Christian Borntraeger wrote:
>
>
> On 07/12/2018 01:10 PM, David Woodhouse wrote:
>> On Thu, 2018-07-12 at 13:00 +0200, Christian Borntraeger wrote:
>>>
>>> On s390 this seems to add about 10ns (~3%) for a guest exit/rentry
>>> microbenchmark mostly due to rcu_eqs_ente
On 07/12/2018 01:10 PM, David Woodhouse wrote:
> On Thu, 2018-07-12 at 13:00 +0200, Christian Borntraeger wrote:
>>
>> On s390 this seems to add about 10ns (~3%) for a guest exit/rentry
>> microbenchmark mostly due to rcu_eqs_enter and rcu_eqs_exit now being
>> visible in perf samples. The olde
On Thu, 2018-07-12 at 13:00 +0200, Christian Borntraeger wrote:
>
> On s390 this seems to add about 10ns (~3%) for a guest exit/rentry
> microbenchmark mostly due to rcu_eqs_enter and rcu_eqs_exit now being
> visible in perf samples. The older interface was cheaper.
Well, the older interface was
On 07/12/2018 10:31 AM, David Woodhouse wrote:
>
>
> On Wed, 2018-07-11 at 16:47 -0700, Paul E. McKenney wrote:
>>
What changed was RCU's reactions to longish grace periods. It used to
be very aggressive about forcing the scheduler to do otherwise-unneeded
context switches, whi
On Thu, 2018-07-12 at 08:21 +0200, Christian Borntraeger wrote:
>
> Is there a single patch that that I can test or do I have to combine
> all the pieces that are sprinkled in this mail thread?
I believe it should be just these two commits, and the first is
probably optional as the second makes i
On Wed, 2018-07-11 at 16:47 -0700, Paul E. McKenney wrote:
>
> > > What changed was RCU's reactions to longish grace periods. It used to
> > > be very aggressive about forcing the scheduler to do otherwise-unneeded
> > > context switches, which became a problem somewhere between v4.9 and v4.15.
On 07/12/2018 01:37 AM, Paul E. McKenney wrote:
> On Wed, Jul 11, 2018 at 02:32:59PM -0700, Paul E. McKenney wrote:
>> On Wed, Jul 11, 2018 at 11:11:19PM +0200, Christian Borntraeger wrote:
>>>
>>>
>>> On 07/11/2018 10:27 PM, Paul E. McKenney wrote:
On Wed, Jul 11, 2018 at 08:39:36PM +0200,
On Wed, Jul 11, 2018 at 04:37:27PM -0700, Paul E. McKenney wrote:
> On Wed, Jul 11, 2018 at 02:32:59PM -0700, Paul E. McKenney wrote:
> > On Wed, Jul 11, 2018 at 11:11:19PM +0200, Christian Borntraeger wrote:
> > >
> > >
> > > On 07/11/2018 10:27 PM, Paul E. McKenney wrote:
> > > > On Wed, Jul 11
On Wed, Jul 11, 2018 at 11:39:10PM +0200, Christian Borntraeger wrote:
>
>
> On 07/11/2018 11:32 PM, Paul E. McKenney wrote:
> > On Wed, Jul 11, 2018 at 11:11:19PM +0200, Christian Borntraeger wrote:
> >>
> >>
> >> On 07/11/2018 10:27 PM, Paul E. McKenney wrote:
> >>> On Wed, Jul 11, 2018 at 08:3
On Wed, Jul 11, 2018 at 02:32:59PM -0700, Paul E. McKenney wrote:
> On Wed, Jul 11, 2018 at 11:11:19PM +0200, Christian Borntraeger wrote:
> >
> >
> > On 07/11/2018 10:27 PM, Paul E. McKenney wrote:
> > > On Wed, Jul 11, 2018 at 08:39:36PM +0200, Christian Borntraeger wrote:
> > >>
> > >>
> > >>
On 07/11/2018 11:32 PM, Paul E. McKenney wrote:
> On Wed, Jul 11, 2018 at 11:11:19PM +0200, Christian Borntraeger wrote:
>>
>>
>> On 07/11/2018 10:27 PM, Paul E. McKenney wrote:
>>> On Wed, Jul 11, 2018 at 08:39:36PM +0200, Christian Borntraeger wrote:
On 07/11/2018 08:36 PM, Paul
On Wed, Jul 11, 2018 at 11:11:19PM +0200, Christian Borntraeger wrote:
>
>
> On 07/11/2018 10:27 PM, Paul E. McKenney wrote:
> > On Wed, Jul 11, 2018 at 08:39:36PM +0200, Christian Borntraeger wrote:
> >>
> >>
> >> On 07/11/2018 08:36 PM, Paul E. McKenney wrote:
> >>> On Wed, Jul 11, 2018 at 11:2
On 07/11/2018 10:27 PM, Paul E. McKenney wrote:
> On Wed, Jul 11, 2018 at 08:39:36PM +0200, Christian Borntraeger wrote:
>>
>>
>> On 07/11/2018 08:36 PM, Paul E. McKenney wrote:
>>> On Wed, Jul 11, 2018 at 11:20:53AM -0700, Paul E. McKenney wrote:
On Wed, Jul 11, 2018 at 07:01:01PM +0100, D
On Wed, Jul 11, 2018 at 09:54:52PM +0100, David Woodhouse wrote:
> On Wed, 2018-07-11 at 13:27 -0700, Paul E. McKenney wrote:
> >
> > Something like this, on top of the earlier patch? I am not at all
> > confident of this patch because there might be other entry/exit
> > paths I am missing. Plus
On Wed, 2018-07-11 at 13:27 -0700, Paul E. McKenney wrote:
>
> Something like this, on top of the earlier patch? I am not at all
> confident of this patch because there might be other entry/exit
> paths I am missing. Plus there might be RCU uses on the arch-
> specific patch to and from the gues
On Wed, Jul 11, 2018 at 08:39:36PM +0200, Christian Borntraeger wrote:
>
>
> On 07/11/2018 08:36 PM, Paul E. McKenney wrote:
> > On Wed, Jul 11, 2018 at 11:20:53AM -0700, Paul E. McKenney wrote:
> >> On Wed, Jul 11, 2018 at 07:01:01PM +0100, David Woodhouse wrote:
> >>> From: David Woodhouse
> >
On 07/11/2018 08:36 PM, Paul E. McKenney wrote:
> On Wed, Jul 11, 2018 at 11:20:53AM -0700, Paul E. McKenney wrote:
>> On Wed, Jul 11, 2018 at 07:01:01PM +0100, David Woodhouse wrote:
>>> From: David Woodhouse
>>>
>>> RCU can spend long periods of time waiting for a CPU which is actually in
>>>
On Wed, Jul 11, 2018 at 11:20:53AM -0700, Paul E. McKenney wrote:
> On Wed, Jul 11, 2018 at 07:01:01PM +0100, David Woodhouse wrote:
> > From: David Woodhouse
> >
> > RCU can spend long periods of time waiting for a CPU which is actually in
> > KVM guest mode, entirely pointlessly. Treat it like
On Wed, Jul 11, 2018 at 07:01:01PM +0100, David Woodhouse wrote:
> From: David Woodhouse
>
> RCU can spend long periods of time waiting for a CPU which is actually in
> KVM guest mode, entirely pointlessly. Treat it like the idle and userspace
> modes, and don't wait for it.
>
> Signed-off-by: D
From: David Woodhouse
RCU can spend long periods of time waiting for a CPU which is actually in
KVM guest mode, entirely pointlessly. Treat it like the idle and userspace
modes, and don't wait for it.
Signed-off-by: David Woodhouse
---
arch/x86/kvm/x86.c | 2 ++
include/linux/rcupdate.h
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