Re: [PATCH] kvm: x86: make lapic hrtimer pinned

2016-04-23 Thread Wanpeng Li
2016-04-22 21:12 GMT+08:00 Luiz Capitulino : > On Fri, 22 Apr 2016 07:12:51 +0800 > Wanpeng Li wrote: > >> 2016-04-05 20:40 GMT+08:00 Luiz Capitulino : >> > On Tue, 5 Apr 2016 14:18:01 +0800 >> > Yang Zhang wrote: >> > >> >> On 2016/4/5 5:00, Rik van Riel wrote: >> >> > On Mon, 2016-04-04 at 16:4

Re: [PATCH] kvm: x86: make lapic hrtimer pinned

2016-04-22 Thread Luiz Capitulino
On Fri, 22 Apr 2016 07:12:51 +0800 Wanpeng Li wrote: > 2016-04-05 20:40 GMT+08:00 Luiz Capitulino : > > On Tue, 5 Apr 2016 14:18:01 +0800 > > Yang Zhang wrote: > > > >> On 2016/4/5 5:00, Rik van Riel wrote: > >> > On Mon, 2016-04-04 at 16:46 -0400, Luiz Capitulino wrote: > >> >> When a vCP

Re: [PATCH] kvm: x86: make lapic hrtimer pinned

2016-04-21 Thread Wanpeng Li
2016-04-05 20:40 GMT+08:00 Luiz Capitulino : > On Tue, 5 Apr 2016 14:18:01 +0800 > Yang Zhang wrote: > >> On 2016/4/5 5:00, Rik van Riel wrote: >> > On Mon, 2016-04-04 at 16:46 -0400, Luiz Capitulino wrote: >> >> When a vCPU runs on a nohz_full core, the hrtimer used by >> >> the lapic emulation c

Re: [PATCH] kvm: x86: make lapic hrtimer pinned

2016-04-06 Thread Yang Zhang
On 2016/4/5 23:54, Radim Krčmář wrote: 2016-04-05 14:18+0800, Yang Zhang: On 2016/4/5 5:00, Rik van Riel wrote: Given that delivering a timer to a guest seems to involve trapping from the guest to the host, anyway, I don't see a downside to your patch. If that is ever changed (eg. allowing del

Re: [PATCH] kvm: x86: make lapic hrtimer pinned

2016-04-05 Thread Radim Krčmář
2016-04-05 14:18+0800, Yang Zhang: > On 2016/4/5 5:00, Rik van Riel wrote: >>Given that delivering a timer to a guest seems to >>involve trapping from the guest to the host, anyway, >>I don't see a downside to your patch. >> >>If that is ever changed (eg. allowing delivery of >>a timer interrupt to

Re: [PATCH] kvm: x86: make lapic hrtimer pinned

2016-04-05 Thread Luiz Capitulino
On Tue, 5 Apr 2016 14:18:01 +0800 Yang Zhang wrote: > On 2016/4/5 5:00, Rik van Riel wrote: > > On Mon, 2016-04-04 at 16:46 -0400, Luiz Capitulino wrote: > >> When a vCPU runs on a nohz_full core, the hrtimer used by > >> the lapic emulation code can be migrated to another core. > >> When this ha

Re: [PATCH] kvm: x86: make lapic hrtimer pinned

2016-04-05 Thread Paolo Bonzini
On 04/04/2016 22:46, Luiz Capitulino wrote: > When a vCPU runs on a nohz_full core, the hrtimer used by > the lapic emulation code can be migrated to another core. > When this happens, it's possible to observe milisecond > latency when delivering timer IRQs to KVM guests. > > The huge latency is m

Re: [PATCH] kvm: x86: make lapic hrtimer pinned

2016-04-04 Thread Yang Zhang
On 2016/4/5 5:00, Rik van Riel wrote: On Mon, 2016-04-04 at 16:46 -0400, Luiz Capitulino wrote: When a vCPU runs on a nohz_full core, the hrtimer used by the lapic emulation code can be migrated to another core. When this happens, it's possible to observe milisecond latency when delivering timer

Re: [PATCH] kvm: x86: make lapic hrtimer pinned

2016-04-04 Thread Rik van Riel
On Mon, 2016-04-04 at 16:46 -0400, Luiz Capitulino wrote: > When a vCPU runs on a nohz_full core, the hrtimer used by > the lapic emulation code can be migrated to another core. > When this happens, it's possible to observe milisecond > latency when delivering timer IRQs to KVM guests. > > The hug

[PATCH] kvm: x86: make lapic hrtimer pinned

2016-04-04 Thread Luiz Capitulino
When a vCPU runs on a nohz_full core, the hrtimer used by the lapic emulation code can be migrated to another core. When this happens, it's possible to observe milisecond latency when delivering timer IRQs to KVM guests. The huge latency is mainly due to the fact that apic_timer_fn() expects to ru