From: Marc Zyngier <marc.zyngier@arm.com>
To: Andrew Murray <andrew.murray@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Julien Thierry <julien.thierry@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
joro@8bytes.org, Suzuki K Poulose <suzuki.poulose@arm.com>,
Will Deacon <will.deacon@arm.com>,
Christoffer Dall <christoffer.dall@arm.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v8 4/5] arm64: arm_pmu: Add support for exclude_host/exclude_guest attributes
Date: Tue, 08 Jan 2019 11:50:59 +0000 [thread overview]
Message-ID: <868szvbc64.wl-marc.zyngier@arm.com> (raw)
In-Reply-To: <20190108112512.GA56789@e119886-lin.cambridge.arm.com>
On Tue, 08 Jan 2019 11:25:13 +0000,
Andrew Murray <andrew.murray@arm.com> wrote:
Hi Andrew,
> My only doubt about this is as follows. If, on a KVM host you run this:
>
> perf stat -e cycles:H lkvm run ...
>
> then on the VHE host the cycles reported represents the entire non-guest cycles
> associated with running the guest.
>
> On a !VHE, the cycles reported exclude EL2 (with or without this patch) and
> thus you don't get a representation of all the non-guest cycles associated with
> the guest. However without this patch you could at least still run:
>
> perf stat -e cycles:H -e cycles:h lkvm run ...
>
> and then add the two cycle counts together to get something comparative with
> the VHE host.
>
> If the above patch represents the desired semantics, then perhaps we must count
> both EL1 and *EL2* for !exclude_kernel on !VHE. In fact I think we should do
> this anyway and remove a little complexity from armv8pmu_set_event_filter.
> Thoughts?
I'm not sure we should hide the architectural differences between VHE
and !VHE. If you're trying to measure what is happening at in the
hypervisor, you can't reason about it while ignoring the dual nature
of !VHE.
Thanks,
M.
--
Jazz is not dead, it just smell funny.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-01-08 11:51 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-12 10:29 [PATCH v8 0/5] arm64: Support perf event modifiers :G and :H Andrew Murray
2018-12-12 10:29 ` [PATCH v8 1/5] arm64: arm_pmu: remove unnecessary isb instruction Andrew Murray
2018-12-12 10:29 ` [PATCH v8 2/5] arm64: KVM: encapsulate kvm_cpu_context in kvm_host_data Andrew Murray
2018-12-12 10:37 ` Suzuki K Poulose
2018-12-12 12:31 ` Andrew Murray
2018-12-18 11:40 ` Christoffer Dall
2018-12-12 10:29 ` [PATCH v8 3/5] arm64: KVM: add accessors to track guest/host only counters Andrew Murray
2018-12-12 10:56 ` Suzuki K Poulose
2018-12-12 10:29 ` [PATCH v8 4/5] arm64: arm_pmu: Add support for exclude_host/exclude_guest attributes Andrew Murray
2018-12-12 10:42 ` Suzuki K Poulose
2018-12-12 10:47 ` Julien Thierry
2018-12-12 10:51 ` Suzuki K Poulose
2018-12-12 10:55 ` Suzuki K Poulose
2018-12-12 14:38 ` Andrew Murray
2018-12-18 12:02 ` Christoffer Dall
2018-12-18 13:25 ` Andrew Murray
2018-12-18 14:38 ` Christoffer Dall
2018-12-18 16:27 ` Andrew Murray
2018-12-18 18:51 ` Christoffer Dall
2018-12-18 19:19 ` Andrew Jones
2019-01-04 15:32 ` Will Deacon
2019-01-08 10:18 ` Christoffer Dall
2019-01-08 11:25 ` Andrew Murray
2019-01-08 11:50 ` Marc Zyngier [this message]
2019-01-08 12:03 ` Christoffer Dall
2019-01-08 12:12 ` Marc Zyngier
2019-01-08 12:20 ` Christoffer Dall
2019-01-08 12:14 ` Christoffer Dall
2019-01-08 12:39 ` Andrew Murray
2018-12-12 10:29 ` [PATCH v8 5/5] arm64: KVM: Enable support for :G/:H perf event modifiers Andrew Murray
2018-12-12 10:53 ` Suzuki K Poulose
2018-12-12 14:46 ` Andrew Murray
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=868szvbc64.wl-marc.zyngier@arm.com \
--to=marc.zyngier@arm.com \
--cc=andrew.murray@arm.com \
--cc=catalin.marinas@arm.com \
--cc=christoffer.dall@arm.com \
--cc=joro@8bytes.org \
--cc=julien.thierry@arm.com \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=suzuki.poulose@arm.com \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).