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Message-ID: <CAM9d7ciFpGhQat3esWLBUDNc1pzAqVw+8d+oX-WJeN+KJfW8Ew@mail.gmail.com>
Date: Wed, 22 May 2024 21:23:30 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: yskelg@...il.com
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>, Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>,
Austin Kim <austindh.kim@...il.com>, shjy180909@...il.com,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] buitin-kvm: Update cmd_kvm() to check perf_host value
Hello,
On Wed, May 15, 2024 at 12:54 PM <yskelg@...il.com> wrote:
>
> From: Yunseong Kim <yskelg@...il.com>
>
> According to perf-kvm.txt, the default operation is --guest, meaning
> perf_host should be set to false and perf_guest to true. Currently,
> the incorrect usage of --no-host and --no-guest still results in
> the default --guest operation.
Hmm, right.. This is not good.
>
> This patch updates the usage messages to include the --no-guest option
> for those who only want host data, as well as the --no-host and
> --no-guest case.
I'm not sure if it's worth mentioning the host-only use case which is
not expected for this command. I think it's enough to warn the
no-host and no-guest use cases.
>
> Signed-off-by: Yunseong Kim <yskelg@...il.com>
> ---
> tools/perf/builtin-kvm.c | 19 +++++++++++++------
> 1 file changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
> index 71165036e4ca..654a07658cdd 100644
> --- a/tools/perf/builtin-kvm.c
> +++ b/tools/perf/builtin-kvm.c
> @@ -2129,7 +2129,7 @@ int cmd_kvm(int argc, const char **argv)
> OPT_BOOLEAN(0, "guest", &perf_guest,
> "Collect guest os data"),
> OPT_BOOLEAN(0, "host", &perf_host,
> - "Collect host os data"),
> + "Collect host os data. Host only with --host --no-guest"),
> OPT_STRING(0, "guestmount", &symbol_conf.guestmount, "directory",
> "guest mount directory under which every guest os"
> " instance has a subdir"),
> @@ -2150,16 +2150,23 @@ int cmd_kvm(int argc, const char **argv)
> "buildid-list", "stat", NULL };
> const char *kvm_usage[] = { NULL, NULL };
>
> - perf_host = 0;
> - perf_guest = 1;
> + /*
> + * tools/perf/Documentation/perf-kvm.txt
> + *
> + * Default('') -> perf.data.guest
> + * --host -> perf.data.kvm
> + * --guest -> perf.data.guest
> + * --host --guest -> perf.data.kvm
> + * --host --no-guest -> perf.data.host
> + */
> + perf_host = false;
> + perf_guest = true;
Probably not needed.
>
> argc = parse_options_subcommand(argc, argv, kvm_options, kvm_subcommands, kvm_usage,
> PARSE_OPT_STOP_AT_NON_OPTION);
> - if (!argc)
> + if (!argc || (!perf_host && !perf_guest))
> usage_with_options(kvm_usage, kvm_options);
>
> - if (!perf_host)
> - perf_guest = 1;
Instead of showing the whole usage, I think it's better to
print a specific message for this case.
Oh, I've realized that we have 'h' modifier for hypervisors
(on ARM64?) Then maybe no-host + no-guest is a valid
combination. Probably we need to add --hypervisor option
then.
Thanks,
Namhyung
>
> if (!file_name) {
> file_name = get_filename_for_perf_kvm();
> --
> 2.34.1
>
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