From: Punit Agrawal <punit.agrawal@arm.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, Marc Zyngier <marc.zyngier@arm.com>,
Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH 0/7] Add support for monitoring guest TLB operations
Date: Wed, 17 Aug 2016 18:20:14 +0100 [thread overview]
Message-ID: <878tvvtir5.fsf@e105922-lin.cambridge.arm.com> (raw)
In-Reply-To: <a553745d-a527-b2ba-7cfa-f688786d5dc3@redhat.com> (Paolo Bonzini's message of "Wed, 17 Aug 2016 19:02:32 +0200")
Paolo Bonzini <pbonzini@redhat.com> writes:
> On 17/08/2016 19:01, Punit Agrawal wrote:
>>> Can you explain what this is used for? In other words, why would this
>>> be used instead of just running perf in the guest?
>>
>> As TLB maintenance operations are synchronised in hardware, they can
>> impact performance beyond the guest. The operations generate traffic on
>> the interconnect and depending on the implementation, they can also
>> affect the remote TLB's translation bandwidth.
>>
>> These patches are useful on systems where the host and guest are
>> controlled by different users - the guest could be running arbitrary
>> software.
>>
>> Having the ability to monitor the usage of guest TLB invalidations in
>> the host can be useful to diagnose performance issues on such systems.
>
> Are there hardware performance counters for these operations?
That would have been ideal! There are PMU events defined for TLB
accesses and refills but unhelpfully none of them track maintenance
operations.
>
> Paolo
> _______________________________________________
> kvmarm mailing list
> kvmarm@lists.cs.columbia.edu
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
next prev parent reply other threads:[~2016-08-17 17:22 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-16 10:45 Punit Agrawal
2016-08-16 10:45 ` [RFC PATCH 1/7] perf/trace: Add notification for perf trace events Punit Agrawal
2016-08-31 11:01 ` Punit Agrawal
2016-08-16 10:45 ` [RFC PATCH 2/7] KVM: Track the pid of the VM process Punit Agrawal
2016-08-16 10:45 ` [RFC PATCH 3/7] KVM: arm/arm64: Register perf trace event notifier Punit Agrawal
2016-08-16 10:45 ` [RFC PATCH 4/7] arm64: tlbflush.h: add __tlbi() macro Punit Agrawal
2016-08-19 13:24 ` Will Deacon
2016-08-19 13:34 ` Punit Agrawal
2016-08-16 10:45 ` [RFC PATCH 5/7] arm64/kvm: hyp: tlb: use __tlbi() helper Punit Agrawal
2016-08-16 10:45 ` [RFC PATCH 6/7] arm64: KVM: Handle trappable TLB instructions Punit Agrawal
2016-08-19 15:18 ` Will Deacon
2016-08-24 10:40 ` Punit Agrawal
2016-08-26 9:37 ` Punit Agrawal
2016-08-26 12:21 ` Marc Zyngier
2016-09-01 14:55 ` Will Deacon
2016-09-01 18:29 ` Punit Agrawal
2016-08-16 10:45 ` [RFC PATCH 7/7] arm64: KVM: Enable selective trapping of " Punit Agrawal
2016-08-17 15:58 ` [RFC PATCH 0/7] Add support for monitoring guest TLB operations Paolo Bonzini
2016-08-17 17:01 ` Punit Agrawal
2016-08-17 17:02 ` Paolo Bonzini
2016-08-17 17:20 ` Punit Agrawal [this message]
2016-08-18 7:04 ` Paolo Bonzini
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