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From: Jiri Olsa <jolsa@redhat.com>
To: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Namhyung Kim <namhyung@kernel.org>,
	linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
	Jin Yao <yao.jin@linux.intel.com>,
	John Garry <john.garry@huawei.com>, Paul Clarke <pc@us.ibm.com>,
	kajoljain <kjain@linux.ibm.com>,
	Stephane Eranian <eranian@google.com>,
	Sandeep Dasgupta <sdasgup@google.com>,
	linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v2 5/5] perf metric: Don't compute unused events.
Date: Thu, 19 Nov 2020 21:59:20 +0100
Message-ID: <20201119205920.GM1475102@krava> (raw)
In-Reply-To: <20201118050335.2347358-6-irogers@google.com>

On Tue, Nov 17, 2020 at 09:03:35PM -0800, Ian Rogers wrote:

SNIP

> +			ids__free($1.ids);
> +			ids__free($3.ids);
> +		}
> +	} else {
> +		$$.val = NAN;
> +		$$.ids = ids__union($1.ids, $3.ids);
> +	}
> +}
> +| expr '*' expr
> +{
> +	if (!compute_ids || (isfinite($1.val) && isfinite($3.val))) {
> +		$$.val = $1.val * $3.val;
> +		$$.ids = NULL;
> +		if (compute_ids) {
> +			ids__free($1.ids);
> +			ids__free($3.ids);
> +		}
> +	} else {
> +		$$.val = NAN;
> +		$$.ids = ids__union($1.ids, $3.ids);
> +	}
> +}
> +| expr '/' expr
> +{
> +	if (fpclassify($3.val) == FP_ZERO) {
> +		pr_debug("division by zero\n");
> +		YYABORT;
> +	} else if (!compute_ids || (isfinite($1.val) && isfinite($3.val))) {
> +		$$.val = $1.val / $3.val;
> +		$$.ids = NULL;

hum, I'm confused with this.. compute_ids with finite values?
why do we erase ids then? also val should be NAN then, no?
could you please put in some comment with reasoning?

thanks,
jirka


  reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-18  5:03 [PATCH v2 0/5] Don't compute events that won't be used in a metric Ian Rogers
2020-11-18  5:03 ` [PATCH v2 1/5] perf metric: Restructure struct expr_parse_ctx Ian Rogers
2020-11-18  5:03 ` [PATCH v2 2/5] perf metric: Use NAN for missing event IDs Ian Rogers
2020-11-19 19:47   ` Jiri Olsa
2020-11-18  5:03 ` [PATCH v2 3/5] perf metric: Rename expr__find_other Ian Rogers
2020-11-18  5:03 ` [PATCH v2 4/5] perf metric: Add utilities to work on ids map Ian Rogers
2020-11-18  5:03 ` [PATCH v2 5/5] perf metric: Don't compute unused events Ian Rogers
2020-11-19 20:59   ` Jiri Olsa [this message]
     [not found]     ` <CAP-5=fWjzwDg7SbfBq+mHqT+zDEEpei8M5AF8+Bk8sU19Ta_hg@mail.gmail.com>
2020-11-20 19:35       ` Jiri Olsa

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