Guest PMU - Revision history

Bsd: added categories

2015-05-31T14:08:08Z

added categories

← Older revision		Revision as of 10:08, 31 May 2015
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	Compile kernel and QEMU from repositories above. Reboot into the new kernel. Make sure that nmi watchdog is disabled on a host. Run QEMU with "-cpu host". Run perf inside a guest.		Compile kernel and QEMU from repositories above. Reboot into the new kernel. Make sure that nmi watchdog is disabled on a host. Run QEMU with "-cpu host". Run perf inside a guest.

			[[Category:Architecture]][[Category:Docs]][[Category:Historical]]

Gleb at 10:21, 5 January 2012

2012-01-05T10:21:15Z

← Older revision		Revision as of 06:21, 5 January 2012
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	= Git repositories =		= Git repositories =

	kernel: git://github.com/avikivity/kvm.git		* kernel: git://github.com/avikivity/kvm.git
	QEMU: git://git.kernel.org/pub/scm/virt/kvm/qemu-kvm.git		* QEMU: git://git.kernel.org/pub/scm/virt/kvm/qemu-kvm.git

	= Putting it all together =		= Putting it all together =

	Compile kernel and QEMU from repositories above. Reboot into the new kernel. Make sure that nmi watchdog is disabled on a host. Run QEMU with "-cpu host". Run perf inside a guest.		Compile kernel and QEMU from repositories above. Reboot into the new kernel. Make sure that nmi watchdog is disabled on a host. Run QEMU with "-cpu host". Run perf inside a guest.

Gleb at 10:20, 5 January 2012

2012-01-05T10:20:49Z

← Older revision		Revision as of 06:20, 5 January 2012
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	= Git repositories =		= Git repositories =

	~~Guest PMU~~: git://github.com/avikivity/kvm.git		kernel: git://github.com/avikivity/kvm.git
			QEMU: git://git.kernel.org/pub/scm/virt/kvm/qemu-kvm.git

			= Putting it all together =

			Compile kernel and QEMU from repositories above. Reboot into the new kernel. Make sure that nmi watchdog is disabled on a host. Run QEMU with "-cpu host". Run perf inside a guest.

Gleb at 09:39, 14 December 2011

2011-12-14T09:39:28Z

← Older revision		Revision as of 05:39, 14 December 2011
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	* Add a paravirt batch MSR read/write facility, update perf to use it when available		* Add a paravirt batch MSR read/write facility, update perf to use it when available
	* Change perf to use an ordinary interrupt instead of NMI when profiling only user space, or only a guest (reduces work in NMI context)		* Change perf to use an ordinary interrupt instead of NMI when profiling only user space, or only a guest (reduces work in NMI context)

			= Caveats =

			* NMI watchdog on a host reduces amount of performance counters available to a gust, but guest will not know this and if it will try to use all performance counters one of them will fail. It is better to disable NMI watchdog on a host.


	= Git repositories =		= Git repositories =

	Guest PMU: git://github.com/avikivity/kvm.git		Guest PMU: git://github.com/avikivity/kvm.git

Gleb at 14:03, 12 December 2011

2011-12-12T14:03:58Z

← Older revision		Revision as of 10:03, 12 December 2011
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	= Current status =		= Current status =

	Version 1 Architectural PMU on Intel and AMD hosts is implemented and works.		Version 2 Architectural PMU on Intel and AMD hosts is implemented and works.

	= TODO =		= TODO =

	== Guest visible features ==		== Guest visible features ==
	* Implement Version 2 Architectural PMU - allows faster switch times using PERF_GLOBAL_ENABLE MSR
	* Implement Version 3 Architectural PMU		* Implement Version 3 Architectural PMU
	* Model specific PMU - allows access to more events and support for more tools; but restricts live migration capabilities		* PEBS - Preceise Event Based Sampling - allows examining program state (problematic)
	** Need per-event validation to avoid leaking socket-wide or core-wide information		* BTS - Branch Trace Store - allows tracing program execution accurately (problematic)
	* PEBS - Preceise Event Based Sampling - allows examining program state
	* BTS - Branch Trace Store - allows tracing program execution accurately

	== Accuracy ==		== Accuracy ==

	* ~~Update Joerg Roedel's exclude_guest/exclude_host patchset to support Intel hosts, using vmx's ability to load PERF_GLOBAL_ENABLE on vmentry/vmexit~~		* Do not pin perf_events. Schedule them as a group and scale PM counter value.

	== Performance ==		== Performance ==

	* ~~Investigate reports that enabling the~~ guest ~~PMU reduces performance~~		* Let a guest control MSR_CORE_PERF_GLOBAL_CTRL if there is no guest monitoring event on a host.
	* Update the perf_event subsystem to make use of the PERF_GLOBAL_ENABLE MSR to speed up context switching, on both guest and host		* Update the perf_event subsystem to make use of the PERF_GLOBAL_ENABLE MSR to speed up context switching, on both guest and host
	* Check whether perf_event does unnecessary RMW operations on MSRs, which are significantly slow in a guest		* Check whether perf_event does unnecessary RMW operations on MSRs, which are significantly slow in a guest
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	= Git repositories =		= Git repositories =

	Guest PMU: git://github.com/avikivity/kvm.git ~~pmu~~		Guest PMU: git://github.com/avikivity/kvm.git

	~~exclude_host: git://github.com/avikivity/kvm.git perf-guest-counting~~

Iro: Fix presentation link

2011-09-28T08:56:15Z

Fix presentation link

← Older revision		Revision as of 04:56, 28 September 2011
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	Guest PMU (Performance Monitoring Unit) currently exists in the form of an out-of-tree patchset.		Guest PMU (Performance Monitoring Unit) currently exists in the form of an out-of-tree patchset.

	See the [http://www.linux-kvm.org/wiki/images/6/6d/Kvm-forum-2011-performance-monitoring.pdf\|KVM Forum 2011 presentation] about the state as of August 2011.		See the [http://www.linux-kvm.org/wiki/images/6/6d/Kvm-forum-2011-performance-monitoring.pdf KVM Forum 2011 presentation] about the state as of August 2011.

	= Current status =		= Current status =

AviKivity at 06:41, 6 September 2011

2011-09-06T06:41:21Z

← Older revision		Revision as of 02:41, 6 September 2011
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	* Check whether perf_event does unnecessary RMW operations on MSRs, which are significantly slow in a guest		* Check whether perf_event does unnecessary RMW operations on MSRs, which are significantly slow in a guest
	* Add a paravirt batch MSR read/write facility, update perf to use it when available		* Add a paravirt batch MSR read/write facility, update perf to use it when available
	* Change perf to use an ordinary interrupt instead of NMI when profiling only user space (reduces work in NMI context)		* Change perf to use an ordinary interrupt instead of NMI when profiling only user space, or only a guest (reduces work in NMI context)

	= Git repositories =		= Git repositories =

AviKivity at 06:40, 6 September 2011

2011-09-06T06:40:16Z

← Older revision		Revision as of 02:40, 6 September 2011
Line 27:		Line 27:
	* Check whether perf_event does unnecessary RMW operations on MSRs, which are significantly slow in a guest		* Check whether perf_event does unnecessary RMW operations on MSRs, which are significantly slow in a guest
	* Add a paravirt batch MSR read/write facility, update perf to use it when available		* Add a paravirt batch MSR read/write facility, update perf to use it when available
			* Change perf to use an ordinary interrupt instead of NMI when profiling only user space (reduces work in NMI context)

	= Git repositories =		= Git repositories =

AviKivity at 14:37, 5 September 2011

2011-09-05T14:37:42Z

← Older revision		Revision as of 10:37, 5 September 2011
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	Guest PMU: git://github.com/avikivity/kvm.git pmu		Guest PMU: git://github.com/avikivity/kvm.git pmu

	exclude_host: git://github.com/avikivity/kvm.git perf-guest-counting		exclude_host: git://github.com/avikivity/kvm.git perf-guest-counting

AviKivity: added git repos

2011-09-05T14:37:26Z

added git repos

← Older revision		Revision as of 10:37, 5 September 2011
Line 27:		Line 27:
	* Check whether perf_event does unnecessary RMW operations on MSRs, which are significantly slow in a guest		* Check whether perf_event does unnecessary RMW operations on MSRs, which are significantly slow in a guest
	* Add a paravirt batch MSR read/write facility, update perf to use it when available		* Add a paravirt batch MSR read/write facility, update perf to use it when available

			= Git repositories =

			Guest PMU: git://github.com/avikivity/kvm.git pmu
			exclude_host: git://github.com/avikivity/kvm.git perf-guest-counting