linux-kernel - Re: [PATCH 03/15 V3] perf c2c: Shared data analyser

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Message-ID: <20140408142321.GW8488@redhat.com>
Date:	Tue, 8 Apr 2014 10:23:21 -0400
From:	Don Zickus <dzickus@...hat.com>
To:	Namhyung Kim <namhyung@...il.com>
Cc:	acme@...stprotocols.net, LKML <linux-kernel@...r.kernel.org>,
	jolsa@...hat.com, jmario@...hat.com, fowles@...each.com,
	peterz@...radead.org, eranian@...gle.com, andi.kleen@...el.com,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Mike Galbraith <efault@....de>,
	Paul Mackerras <paulus@...ba.org>,
	Richard Fowles <rfowles@...hat.com>
Subject: Re: [PATCH 03/15 V3] perf c2c: Shared data analyser

On Tue, Apr 08, 2014 at 03:59:15PM +0900, Namhyung Kim wrote:
> Hi Don,

Oh by the way, thank you for your review.  I will clean up a bunch of
stuff based on your suggestions.

Cheers,
Don

> 
> On Mon, 24 Mar 2014 15:36:54 -0400, Don Zickus wrote:
> > From: Arnaldo Carvalho de Melo <acme@...hat.com>
> >
> > This is the start of a new perf tool that will collect information about
> > memory accesses and analyse it to find things like hot cachelines, etc.
> 
> So why not integrating this into existing 'perf mem' command if it's all
> about analyzing memory accesses?
> 
> >
> > This is basically trying to get a prototype written by Richard Fowles
> > written using the tools/perf coding style and libraries.
> >
> > Start it from 'perf sched', this patch starts the process by adding the
> > 'record' subcommand to collect the needed mem loads and stores samples.
> >
> > It also have the basic 'report' skeleton, resolving the sample address
> > and hooking the events found in a perf.data file with methods to handle
> > them, right now just printing the resolved perf_sample data structure
> > after each event name.
> >
> > [dcz: refreshed to latest upstream changes]
> 
> [SNIP]
> > +perf-c2c(1)
> > +===========
> > +
> > +NAME
> > +----
> > +perf-c2c - Shared Data C2C/HITM Analyzer.
> > +
> > +SYNOPSIS
> > +--------
> > +[verse]
> > +'perf c2c' record
> > +
> > +DESCRIPTION
> > +-----------
> > +These are the variants of perf c2c:
> > +
> > +  'perf c2c record <command>' to record the memory accesses of an arbitrary
> > +  workload.
> > +
> > +SEE ALSO
> > +--------
> > +linkperf:perf-record[1], linkperf:perf-mem[1]
> 
> This document is very terse and only memtions the 'record' subcommand -
> also it's not updated throughout the series.  So I'd like to suggest
> adding a separate documentation patch with full/verbose descriptions at
> the end of this series.
> 
> 
> [SNIP]
> > +static int perf_c2c__read_events(struct perf_c2c *c2c)
> > +{
> > +	int err = -1;
> > +	struct perf_session *session;
> > +	struct perf_data_file file = {
> > +			.path = input_name,
> > +			.mode = PERF_DATA_MODE_READ,
> > +	};
> > +	struct perf_evsel *evsel;
> > +
> > +	session = perf_session__new(&file, 0, &c2c->tool);
> > +	if (session == NULL) {
> > +		pr_debug("No memory for session\n");
> > +		goto out;
> > +	}
> > +
> > +	/* setup the evsel handlers for each event type */
> > +	evlist__for_each(session->evlist, evsel) {
> > +		const char *name = perf_evsel__name(evsel);
> > +		unsigned int i;
> > +
> > +		for (i = 0; i < ARRAY_SIZE(handlers); i++) {
> > +			if (!strcmp(name, handlers[i].name))
> > +				evsel->handler = handlers[i].handler;
> > +		}
> > +	}
> > +
> > +	err = perf_session__process_events(session, &c2c->tool);
> > +	if (err)
> > +		pr_err("Failed to process events, error %d", err);
> 
> You may want to add perf_session__delete() here.
> 
> > +
> > +out:
> > +	return err;
> > +}
> 
> 
> [SNIP]
> > +int cmd_c2c(int argc, const char **argv, const char *prefix __maybe_unused)
> > +{
> > +	struct perf_c2c c2c = {
> > +		.tool = {
> > +			.sample		 = perf_c2c__process_sample,
> > +			.comm		 = perf_event__process_comm,
> > +			.exit		 = perf_event__process_exit,
> > +			.fork		 = perf_event__process_fork,
> > +			.lost		 = perf_event__process_lost,
> 
> It seems that it also needs to handle mmap[2] events otherwise it cannot
> find symbols from an address.
> 
> Thanks,
> Namhyung
> 
> 
> > +			.ordered_samples = true,
> > +		},
> > +	};
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