Hi Eduardo,
2017-11-16 12:54 GMT+08:00 Eduardo Valentin :
> Hey Radim,
>
> On Thu, Nov 09, 2017 at 03:17:33PM +0100, Radim Krčmář wrote:
>
>
>
>>
>> This is what I'm doubting, because the patch is adding about two
>> thousand cycles to every spinlock-taken path.
>> Doesn't this patch yield better
Hey Radim,
On Thu, Nov 09, 2017 at 03:17:33PM +0100, Radim Krčmář wrote:
>
> This is what I'm doubting, because the patch is adding about two
> thousand cycles to every spinlock-taken path.
> Doesn't this patch yield better results?
>
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm
On 10/11/2017 07:07, Wanpeng Li wrote:
>>> You should also add a cpuid flag in kvm part.
>> It is better without that. The flag has no dependency on KVM (kernel
>> hypervisor) code.
> Do you mean -cpu host, +，I think it will result in "warning: host
> doesn't support requested feature: CPUID.4
2017-11-10 15:59 GMT+08:00 Peter Zijlstra :
> On Fri, Nov 10, 2017 at 10:07:56AM +0800, Wanpeng Li wrote:
>
>> >> Also, you should not put cpumask_t on stack, that's 'broken'.
>>
>> Thanks pointing out this. I found a useful comments in arch/x86/kernel/irq.c:
>>
>> /* These two declarations are onl
On Fri, Nov 10, 2017 at 10:07:56AM +0800, Wanpeng Li wrote:
> >> Also, you should not put cpumask_t on stack, that's 'broken'.
>
> Thanks pointing out this. I found a useful comments in arch/x86/kernel/irq.c:
>
> /* These two declarations are only used in check_irq_vectors_for_cpu_disable()
> *
2017-11-10 0:00 GMT+08:00 Radim Krcmar :
> 2017-11-09 20:43+0800, Wanpeng Li:
>> 2017-11-07 4:26 GMT+08:00 Eduardo Valentin :
>> > Currently, the existing qspinlock implementation will fallback to
>> > test-and-set if the hypervisor has not set the PV_UNHALT flag.
>> >
>> > This patch gives the opp
2017-11-10 1:15 GMT+08:00 Peter Zijlstra :
> On Thu, Nov 09, 2017 at 06:12:41PM +0100, Peter Zijlstra wrote:
>> On Thu, Nov 09, 2017 at 05:45:23PM +0100, Radim Krcmar wrote:
>> > 2017-11-09 17:17+0100, Peter Zijlstra:
>> > > On Thu, Nov 09, 2017 at 05:05:36PM +0100, Radim Krcmar wrote:
>> > > > 201
2017-11-09 18:12+0100, Peter Zijlstra:
> On Thu, Nov 09, 2017 at 05:45:23PM +0100, Radim Krcmar wrote:
> > 2017-11-09 17:17+0100, Peter Zijlstra:
> > > On Thu, Nov 09, 2017 at 05:05:36PM +0100, Radim Krcmar wrote:
> > > > 2017-11-09 10:53-0500, Pankaj Gupta:
> > > > > 2] PV TLB should also behave a
2017-11-09 18:28+0100, Peter Zijlstra:
> On Thu, Nov 09, 2017 at 06:15:11PM +0100, Peter Zijlstra wrote:
> > On Thu, Nov 09, 2017 at 06:12:41PM +0100, Peter Zijlstra wrote:
> > > On Thu, Nov 09, 2017 at 05:45:23PM +0100, Radim Krcmar wrote:
> > > > 2017-11-09 17:17+0100, Peter Zijlstra:
> > > > > O
On Thu, Nov 09, 2017 at 06:15:11PM +0100, Peter Zijlstra wrote:
> On Thu, Nov 09, 2017 at 06:12:41PM +0100, Peter Zijlstra wrote:
> > On Thu, Nov 09, 2017 at 05:45:23PM +0100, Radim Krcmar wrote:
> > > 2017-11-09 17:17+0100, Peter Zijlstra:
> > > > On Thu, Nov 09, 2017 at 05:05:36PM +0100, Radim Kr
On Thu, Nov 09, 2017 at 06:12:41PM +0100, Peter Zijlstra wrote:
> On Thu, Nov 09, 2017 at 05:45:23PM +0100, Radim Krcmar wrote:
> > 2017-11-09 17:17+0100, Peter Zijlstra:
> > > On Thu, Nov 09, 2017 at 05:05:36PM +0100, Radim Krcmar wrote:
> > > > 2017-11-09 10:53-0500, Pankaj Gupta:
> > > > > 2] PV
On Thu, Nov 09, 2017 at 05:45:23PM +0100, Radim Krcmar wrote:
> 2017-11-09 17:17+0100, Peter Zijlstra:
> > On Thu, Nov 09, 2017 at 05:05:36PM +0100, Radim Krcmar wrote:
> > > 2017-11-09 10:53-0500, Pankaj Gupta:
> > > > 2] PV TLB should also behave as per option PV_DEDICATED for better
> > > > per
2017-11-09 17:17+0100, Peter Zijlstra:
> On Thu, Nov 09, 2017 at 05:05:36PM +0100, Radim Krcmar wrote:
> > 2017-11-09 10:53-0500, Pankaj Gupta:
> > > 2] PV TLB should also behave as per option PV_DEDICATED for better
> > > performance.
> >
> > Right,
>
> Shouldn't KVM do flush_tlb_other() in any
> Subject: Re: [PATCHv3 1/1] locking/qspinlock/x86: Avoid test-and-set when
> PV_DEDICATED is set
>
> On Thu, Nov 09, 2017 at 05:05:36PM +0100, Radim Krcmar wrote:
> > 2017-11-09 10:53-0500, Pankaj Gupta:
> > > 2] PV TLB should also behave as per option PV_DEDICATED f
On Thu, Nov 09, 2017 at 05:05:36PM +0100, Radim Krcmar wrote:
> 2017-11-09 10:53-0500, Pankaj Gupta:
> > 2] PV TLB should also behave as per option PV_DEDICATED for better
> > performance.
>
> Right,
Shouldn't KVM do flush_tlb_other() in any case? Not sure how
PV_DEDICATED can help with that.
2017-11-09 10:53-0500, Pankaj Gupta:
>
>
> > 2017-11-07 4:26 GMT+08:00 Eduardo Valentin :
> > > Currently, the existing qspinlock implementation will fallback to
> > > test-and-set if the hypervisor has not set the PV_UNHALT flag.
> > >
> > > This patch gives the opportunity to guest kernels to s
2017-11-09 20:43+0800, Wanpeng Li:
> 2017-11-07 4:26 GMT+08:00 Eduardo Valentin :
> > Currently, the existing qspinlock implementation will fallback to
> > test-and-set if the hypervisor has not set the PV_UNHALT flag.
> >
> > This patch gives the opportunity to guest kernels to select
> > between
> 2017-11-07 4:26 GMT+08:00 Eduardo Valentin :
> > Currently, the existing qspinlock implementation will fallback to
> > test-and-set if the hypervisor has not set the PV_UNHALT flag.
> >
> > This patch gives the opportunity to guest kernels to select
> > between test-and-set and the regular queu
2017-11-09 00:55-0800, Eduardo Valentin:
> Hello,
>
> On Wed, Nov 08, 2017 at 06:36:52PM +0100, Radim Krčmář wrote:
> > 2017-11-06 12:26-0800, Eduardo Valentin:
> > > Currently, the existing qspinlock implementation will fallback to
> > > test-and-set if the hypervisor has not set the PV_UNHALT fl
2017-11-07 4:26 GMT+08:00 Eduardo Valentin :
> Currently, the existing qspinlock implementation will fallback to
> test-and-set if the hypervisor has not set the PV_UNHALT flag.
>
> This patch gives the opportunity to guest kernels to select
> between test-and-set and the regular queueu fair lock i
Hello,
On Wed, Nov 08, 2017 at 06:36:52PM +0100, Radim Krčmář wrote:
> 2017-11-06 12:26-0800, Eduardo Valentin:
> > Currently, the existing qspinlock implementation will fallback to
> > test-and-set if the hypervisor has not set the PV_UNHALT flag.
> >
> > This patch gives the opportunity to gues
2017-11-06 12:26-0800, Eduardo Valentin:
> Currently, the existing qspinlock implementation will fallback to
> test-and-set if the hypervisor has not set the PV_UNHALT flag.
>
> This patch gives the opportunity to guest kernels to select
> between test-and-set and the regular queueu fair lock impl
Paolo,
On Tue, Nov 07, 2017 at 01:43:15PM +0100, Paolo Bonzini wrote:
> On 07/11/2017 13:39, Eduardo Valentin wrote:
> >> is this still needed after Waiman's patch to adaptively switch between
> >> tas and pvqspinlock?
> > Can you please point me to it ? Is it already in tip/master?
> >
>
> No,
On 07/11/2017 13:39, Eduardo Valentin wrote:
>> is this still needed after Waiman's patch to adaptively switch between
>> tas and pvqspinlock?
> Can you please point me to it ? Is it already in tip/master?
>
No, he just posted it:
https://marc.info/?l=linux-kernel&m=150972337909996&w=2
Paolo
On Tue, Nov 07, 2017 at 01:23:56PM +0100, Paolo Bonzini wrote:
> On 06/11/2017 21:26, Eduardo Valentin wrote:
> > Currently, the existing qspinlock implementation will fallback to
> > test-and-set if the hypervisor has not set the PV_UNHALT flag.
> >
> > This patch gives the opportunity to guest k
On 06/11/2017 21:26, Eduardo Valentin wrote:
> Currently, the existing qspinlock implementation will fallback to
> test-and-set if the hypervisor has not set the PV_UNHALT flag.
>
> This patch gives the opportunity to guest kernels to select
> between test-and-set and the regular queueu fair lock
Currently, the existing qspinlock implementation will fallback to
test-and-set if the hypervisor has not set the PV_UNHALT flag.
This patch gives the opportunity to guest kernels to select
between test-and-set and the regular queueu fair lock implementation
based on the PV_DEDICATED KVM feature fl
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