linux-kernel - Re: [PATCH 4/4] perf tools: Use sw counter only if hw pmu is not detected

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Date:	Thu, 05 Apr 2012 10:59:04 -0600
From:	David Ahern <dsahern@...il.com>
To:	Robert Richter <robert.richter@....com>
CC:	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] perf tools: Use sw counter only if hw pmu is not
 detected

On 4/5/12 10:26 AM, Robert Richter wrote:
> Use cpu-clock-tick sw counter for cpu-cycles only if there is no hw
> pmu available. This is the case if the syscall reports ENOENT. In
> other cases (e.g. invalid attributes) we don't want the sw counter to
> be used.

Isn't the invalid attributes case handled by the
'} else if (err == EINVAL) {'
case before this switch is done?

David


>
> Signed-off-by: Robert Richter<robert.richter@....com>
> ---
>   tools/perf/builtin-record.c |    2 +-
>   1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index be4e1ee..10b1f1f 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -245,7 +245,7 @@ try_again:
>   			 * based cpu-clock-tick sw counter, which
>   			 * is always available even if no PMU support:
>   			 */
> -			if (attr->type == PERF_TYPE_HARDWARE
> +			if (err == ENOENT&&  attr->type == PERF_TYPE_HARDWARE
>   					&&  attr->config == PERF_COUNT_HW_CPU_CYCLES) {
>
>   				if (verbose)

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