From: Leo Yan <leo.yan@linaro.org>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Peter Zijlstra <peterz@infradead.org>,
John Garry <john.garry@huawei.com>,
linux-kernel@vger.kernel.org,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Suleiman Souhlal <suleiman@google.com>,
Namhyung Kim <namhyung@kernel.org>, Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCHv3] perf kvm: add kvm-stat for arm64
Date: Thu, 17 Sep 2020 18:09:50 +0800 [thread overview]
Message-ID: <20200917100950.GC12548@leoy-ThinkPad-X240s> (raw)
In-Reply-To: <20200917003645.689665-1-sergey.senozhatsky@gmail.com>
[ + Marc ]
On Thu, Sep 17, 2020 at 09:36:45AM +0900, Sergey Senozhatsky wrote:
[...]
> diff --git a/tools/perf/arch/arm64/util/kvm-stat.c b/tools/perf/arch/arm64/util/kvm-stat.c
> new file mode 100644
> index 000000000000..32e58576f186
> --- /dev/null
> +++ b/tools/perf/arch/arm64/util/kvm-stat.c
> @@ -0,0 +1,86 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <errno.h>
> +#include <memory.h>
> +#include "../../util/evsel.h"
> +#include "../../util/kvm-stat.h"
> +#include "arm64_exception_types.h"
> +#include "debug.h"
> +
> +define_exit_reasons_table(arm64_exit_reasons, kvm_arm_exception_type);
> +define_exit_reasons_table(arm64_trap_exit_reasons, kvm_arm_exception_class);
> +
> +const char *kvm_trap_exit_reason = "esr_ec";
> +const char *vcpu_id_str = "id";
On Arm64, ftrace tracepoint "kvm_entry" doesn't contain the field "id"
or field "vcpu_id", thus it always reads out the "id" is 0 and it is
recorded into Perf's structure vcpu_event_record::vcpu_id and assigned
to perf thread's private data "thread::private".
With current code, it will not mess up different vcpus' samples because
now the samples are analyzed based on thread context, but since all
threads' "vcpu_id" is zero, thus all samples are accounted for
"vcpu_id=0" and cannot print out correct result with option "--vcpu":
$ perf kvm stat report --vcpu 4
Analyze events for all VMs, VCPU 4:
VM-EXIT Samples Samples% Time% Min Time Max Time Avg time
Total Samples:0, Total events handled time:0.00us.
This is an issue I observed, if we want to support option "--vcpu",
seems we need to change ftrace event for "kvm_entry", but this will
break ABI.
Essentially, this issue is caused by different archs using different
format for ftrace event "kvm_entry", on x86 it contains feild
"vcpu_id" but arm64 only just records "vcpu_pc".
@Marc, @Will, do you have any suggestion for this? Do you think it's
feasible to add a new field "vcpu_id" into the tracepoint "kvm_entry"
for Arm64's version?
Thanks,
Leo
_______________________________________________
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:[~2020-09-17 10:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-17 0:36 [PATCHv3] perf kvm: add kvm-stat for arm64 Sergey Senozhatsky
2020-09-17 8:47 ` Leo Yan
2020-09-17 9:54 ` Sergey Senozhatsky
2020-09-17 10:09 ` Leo Yan [this message]
2020-09-17 10:12 ` Leo Yan
2020-09-17 10:21 ` Marc Zyngier
2020-09-17 11:00 ` Sergey Senozhatsky
2020-09-17 13:08 ` Leo Yan
2020-09-17 11:42 ` Leo Yan
2020-09-17 11:53 ` Marc Zyngier
2020-09-17 12:52 ` Leo Yan
2020-09-18 0:32 ` Sergey Senozhatsky
2020-09-18 8:20 ` Marc Zyngier
2020-09-18 10:35 ` Sergey Senozhatsky
2020-09-18 10:55 ` Marc Zyngier
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=20200917100950.GC12548@leoy-ThinkPad-X240s \
--to=leo.yan@linaro.org \
--cc=acme@kernel.org \
--cc=john.garry@huawei.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mathieu.poirier@linaro.org \
--cc=namhyung@kernel.org \
--cc=peterz@infradead.org \
--cc=sergey.senozhatsky@gmail.com \
--cc=suleiman@google.com \
--cc=will@kernel.org \
/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).