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SubjectRe: [PATCH 03/15 V3] perf c2c: Shared data analyser
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Hi Don,

On Mon, 24 Mar 2014 15:36:54 -0400, Don Zickus wrote:
> From: Arnaldo Carvalho de Melo <acme@redhat.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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