Re: [PATCH 0/6] kvm: powerpc halt polling updates
On Fri, 14 Oct 2016 11:53:18 +1100 Suraj Jitindar Singh wrote: > This patch series makes some updates and bug fixes to the powerpc kvm-hv > halt polling code. > > The first two patches are concerned with exporting the generic kvm module > parameter variables and accessing these from the powerpc specific code. > > The third patch fixes a bug where changing the global max halt polling > interval module parameter can sometimes have no effect. > > The fourth patch decreases the default global max halt polling interval > to something more sensible. > > The fifth patch contains generic fixups with no functional effect. > > The last patch adds halt polling documentation. I want to enable polling idle in Linux for SPLPAR/KVM as we do for dedicated mode. Essentially the guest OS will spin for a small time before ceding. There will be a lot of interaction between this and halt polling. I think guest polling may still be worthwhile if you have halt polling in the host, although it might be less effective. We should set up some performance testing with various guest/host parameters and see what works best. What have you been testing with so far? Thanks, Nick -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 0/6] kvm: powerpc halt polling updates
On Fri, Oct 14, 2016 at 11:53:18AM +1100, Suraj Jitindar Singh wrote: > This patch series makes some updates and bug fixes to the powerpc kvm-hv > halt polling code. > > The first two patches are concerned with exporting the generic kvm module > parameter variables and accessing these from the powerpc specific code. > > The third patch fixes a bug where changing the global max halt polling > interval module parameter can sometimes have no effect. > > The fourth patch decreases the default global max halt polling interval > to something more sensible. > > The fifth patch contains generic fixups with no functional effect. > > The last patch adds halt polling documentation. > > Suraj Jitindar Singh (6): > kvm: export kvm module parameter variables > powerpc/kvm: Use generic kvm module parameters in kvm-hv > powerpc/kvm: Add check for module parameter halt_poll_ns > powerpc/kvm: Decrease the powerpc default halt poll max value > powerpc/kvm: Comment style and print format fixups > doc/kvm: Add halt polling documentation > > Documentation/virtual/kvm/00-INDEX | 2 + > Documentation/virtual/kvm/halt-polling.txt | 127 > + > arch/powerpc/include/asm/kvm_host.h| 2 +- > arch/powerpc/kvm/book3s_hv.c | 33 ++-- > arch/powerpc/kvm/trace_hv.h| 2 +- > include/linux/kvm_host.h | 4 + > virt/kvm/kvm_main.c| 9 +- > 7 files changed, 149 insertions(+), 30 deletions(-) > create mode 100644 Documentation/virtual/kvm/halt-polling.txt > > -- > 2.5.5 Hi Suraj, I've given this set a quick test and it seems to work fine. I used a repetitive wakeup, using a nanosleep loop in guest userspace (with real time prio), and I was able to cause halt polling to switch on and off as I adjusted halt_poll_ns. I think the new default value is much better: halt polling started (e.g. CPU utilization rose to 100%) once CPU utilization had already risen to about 75%. Cheers, Sam. Tested-by: Sam Bobroff -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH 0/6] kvm: powerpc halt polling updates
This patch series makes some updates and bug fixes to the powerpc kvm-hv halt polling code. The first two patches are concerned with exporting the generic kvm module parameter variables and accessing these from the powerpc specific code. The third patch fixes a bug where changing the global max halt polling interval module parameter can sometimes have no effect. The fourth patch decreases the default global max halt polling interval to something more sensible. The fifth patch contains generic fixups with no functional effect. The last patch adds halt polling documentation. Suraj Jitindar Singh (6): kvm: export kvm module parameter variables powerpc/kvm: Use generic kvm module parameters in kvm-hv powerpc/kvm: Add check for module parameter halt_poll_ns powerpc/kvm: Decrease the powerpc default halt poll max value powerpc/kvm: Comment style and print format fixups doc/kvm: Add halt polling documentation Documentation/virtual/kvm/00-INDEX | 2 + Documentation/virtual/kvm/halt-polling.txt | 127 + arch/powerpc/include/asm/kvm_host.h| 2 +- arch/powerpc/kvm/book3s_hv.c | 33 ++-- arch/powerpc/kvm/trace_hv.h| 2 +- include/linux/kvm_host.h | 4 + virt/kvm/kvm_main.c| 9 +- 7 files changed, 149 insertions(+), 30 deletions(-) create mode 100644 Documentation/virtual/kvm/halt-polling.txt -- 2.5.5 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
