From: Marc Zyngier <maz@kernel.org>
To: Oliver Upton <oupton@google.com>
Cc: kvm@vger.kernel.org, Will Deacon <will@kernel.org>,
Peter Shier <pshier@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/2] KVM: arm64: selftests: Introduce get_set_regs_perf test
Date: Thu, 17 Feb 2022 09:11:53 +0000 [thread overview]
Message-ID: <874k4x502u.wl-maz@kernel.org> (raw)
In-Reply-To: <Yg3Uer/K6n/h6oBz@google.com>
On Thu, 17 Feb 2022 04:52:10 +0000,
Oliver Upton <oupton@google.com> wrote:
>
> Hi Reiji,
>
> First off, thanks for looking into this! Seems like a very useful thing
> to test :-)
>
> On Wed, Feb 16, 2022 at 07:49:47PM -0800, Reiji Watanabe wrote:
> > Introduce a simple performance test of KVM_GET_ONE_REG/KVM_SET_ONE_REG
> > for registers that are returned by KVM_GET_REG_LIST. This is a pseudo
> > process of saving/restoring registers during live migration, and this
> > test quantifies the performance of the process.
> >
> > Signed-off-by: Reiji Watanabe <reijiw@google.com>
> > ---
> > tools/testing/selftests/kvm/.gitignore | 1 +
> > tools/testing/selftests/kvm/Makefile | 1 +
> > .../selftests/kvm/aarch64/get_set_regs_perf.c | 456 ++++++++++++++++++
>
[...]
> Would it make sense to test some opt-in capabilities that expose
> additional registers (PMU, SVE, etc.)?
I think this is important. System registers are usually saved/restored
in groups, and due to the way we walk the sysreg array, timings are
unlikely to be uniform. Getting a grip on that could help restructure
the walking if required (either per-group arrays, or maybe a tree
structure).
Note that all of this could equally apply to the guest trapping (the
walk is the same).
And yes, there are a lot of commonalities with get-reg-list, so
reusing some of the existing infrastructure would be a good thing.
M.
--
Without deviation from the norm, progress is not possible.
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Oliver Upton <oupton@google.com>
Cc: Reiji Watanabe <reijiw@google.com>,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Andrew Jones <drjones@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Will Deacon <will@kernel.org>, Peter Shier <pshier@google.com>,
Ricardo Koller <ricarkol@google.com>,
Jing Zhang <jingzhangos@google.com>,
Raghavendra Rao Anata <rananta@google.com>
Subject: Re: [PATCH 2/2] KVM: arm64: selftests: Introduce get_set_regs_perf test
Date: Thu, 17 Feb 2022 09:11:53 +0000 [thread overview]
Message-ID: <874k4x502u.wl-maz@kernel.org> (raw)
In-Reply-To: <Yg3Uer/K6n/h6oBz@google.com>
On Thu, 17 Feb 2022 04:52:10 +0000,
Oliver Upton <oupton@google.com> wrote:
>
> Hi Reiji,
>
> First off, thanks for looking into this! Seems like a very useful thing
> to test :-)
>
> On Wed, Feb 16, 2022 at 07:49:47PM -0800, Reiji Watanabe wrote:
> > Introduce a simple performance test of KVM_GET_ONE_REG/KVM_SET_ONE_REG
> > for registers that are returned by KVM_GET_REG_LIST. This is a pseudo
> > process of saving/restoring registers during live migration, and this
> > test quantifies the performance of the process.
> >
> > Signed-off-by: Reiji Watanabe <reijiw@google.com>
> > ---
> > tools/testing/selftests/kvm/.gitignore | 1 +
> > tools/testing/selftests/kvm/Makefile | 1 +
> > .../selftests/kvm/aarch64/get_set_regs_perf.c | 456 ++++++++++++++++++
>
[...]
> Would it make sense to test some opt-in capabilities that expose
> additional registers (PMU, SVE, etc.)?
I think this is important. System registers are usually saved/restored
in groups, and due to the way we walk the sysreg array, timings are
unlikely to be uniform. Getting a grip on that could help restructure
the walking if required (either per-group arrays, or maybe a tree
structure).
Note that all of this could equally apply to the guest trapping (the
walk is the same).
And yes, there are a lot of commonalities with get-reg-list, so
reusing some of the existing infrastructure would be a good thing.
M.
--
Without deviation from the norm, progress is not possible.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Oliver Upton <oupton@google.com>
Cc: Reiji Watanabe <reijiw@google.com>,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Andrew Jones <drjones@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Will Deacon <will@kernel.org>, Peter Shier <pshier@google.com>,
Ricardo Koller <ricarkol@google.com>,
Jing Zhang <jingzhangos@google.com>,
Raghavendra Rao Anata <rananta@google.com>
Subject: Re: [PATCH 2/2] KVM: arm64: selftests: Introduce get_set_regs_perf test
Date: Thu, 17 Feb 2022 09:11:53 +0000 [thread overview]
Message-ID: <874k4x502u.wl-maz@kernel.org> (raw)
In-Reply-To: <Yg3Uer/K6n/h6oBz@google.com>
On Thu, 17 Feb 2022 04:52:10 +0000,
Oliver Upton <oupton@google.com> wrote:
>
> Hi Reiji,
>
> First off, thanks for looking into this! Seems like a very useful thing
> to test :-)
>
> On Wed, Feb 16, 2022 at 07:49:47PM -0800, Reiji Watanabe wrote:
> > Introduce a simple performance test of KVM_GET_ONE_REG/KVM_SET_ONE_REG
> > for registers that are returned by KVM_GET_REG_LIST. This is a pseudo
> > process of saving/restoring registers during live migration, and this
> > test quantifies the performance of the process.
> >
> > Signed-off-by: Reiji Watanabe <reijiw@google.com>
> > ---
> > tools/testing/selftests/kvm/.gitignore | 1 +
> > tools/testing/selftests/kvm/Makefile | 1 +
> > .../selftests/kvm/aarch64/get_set_regs_perf.c | 456 ++++++++++++++++++
>
[...]
> Would it make sense to test some opt-in capabilities that expose
> additional registers (PMU, SVE, etc.)?
I think this is important. System registers are usually saved/restored
in groups, and due to the way we walk the sysreg array, timings are
unlikely to be uniform. Getting a grip on that could help restructure
the walking if required (either per-group arrays, or maybe a tree
structure).
Note that all of this could equally apply to the guest trapping (the
walk is the same).
And yes, there are a lot of commonalities with get-reg-list, so
reusing some of the existing infrastructure would be a good thing.
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2022-02-17 9:12 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-17 3:49 [PATCH 1/2] KVM: selftests: kvm_vm_elf_load() and elfhdr_get() should close fd Reiji Watanabe
2022-02-17 3:49 ` Reiji Watanabe
2022-02-17 3:49 ` Reiji Watanabe
2022-02-17 3:49 ` [PATCH 2/2] KVM: arm64: selftests: Introduce get_set_regs_perf test Reiji Watanabe
2022-02-17 3:49 ` Reiji Watanabe
2022-02-17 3:49 ` Reiji Watanabe
2022-02-17 4:52 ` Oliver Upton
2022-02-17 4:52 ` Oliver Upton
2022-02-17 4:52 ` Oliver Upton
2022-02-17 9:11 ` Marc Zyngier [this message]
2022-02-17 9:11 ` Marc Zyngier
2022-02-17 9:11 ` Marc Zyngier
2022-02-19 4:50 ` Reiji Watanabe
2022-02-19 4:50 ` Reiji Watanabe
2022-02-19 4:50 ` Reiji Watanabe
2022-02-19 9:42 ` Marc Zyngier
2022-02-19 9:42 ` Marc Zyngier
2022-02-19 9:42 ` Marc Zyngier
2022-02-19 3:53 ` Reiji Watanabe
2022-02-19 3:53 ` Reiji Watanabe
2022-02-19 3:53 ` Reiji Watanabe
2022-02-17 3:55 ` [PATCH 1/2] KVM: selftests: kvm_vm_elf_load() and elfhdr_get() should close fd Oliver Upton
2022-02-17 3:55 ` Oliver Upton
2022-02-17 3:55 ` Oliver Upton
2022-06-16 14:07 ` Andrew Jones
2022-06-16 14:07 ` Andrew Jones
2022-06-16 14:07 ` Andrew Jones
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