linux-kernel - Re: [PATCH V3 15/17] perf top: Add option to enable the LBR stitching approach

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Message-ID: <20200318121405.GA849721@krava>
Date:   Wed, 18 Mar 2020 13:14:05 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     kan.liang@...ux.intel.com
Cc:     acme@...nel.org, peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org, namhyung@...nel.org,
        adrian.hunter@...el.com, mathieu.poirier@...aro.org,
        ravi.bangoria@...ux.ibm.com, alexey.budankov@...ux.intel.com,
        vitaly.slobodskoy@...el.com, pavel.gerasimov@...el.com,
        mpe@...erman.id.au, eranian@...gle.com, ak@...ux.intel.com
Subject: Re: [PATCH V3 15/17] perf top: Add option to enable the LBR
 stitching approach

On Fri, Mar 13, 2020 at 11:33:17AM -0700, kan.liang@...ux.intel.com wrote:

SNIP

>  #include "util/top.h"
> @@ -766,6 +767,9 @@ static void perf_event__process_sample(struct perf_tool *tool,
>  	if (machine__resolve(machine, &al, sample) < 0)
>  		return;
>  
> +	if (top->stitch_lbr)
> +		al.thread->lbr_stitch_enable = true;
> +
>  	if (!machine->kptr_restrict_warned &&
>  	    symbol_conf.kptr_restrict &&
>  	    al.cpumode == PERF_RECORD_MISC_KERNEL) {
> @@ -1543,6 +1547,8 @@ int cmd_top(int argc, const char **argv)
>  			"number of thread to run event synthesize"),
>  	OPT_BOOLEAN(0, "namespaces", &opts->record_namespaces,
>  		    "Record namespaces events"),
> +	OPT_BOOLEAN(0, "stitch-lbr", &top.stitch_lbr,
> +		    "Enable LBR callgraph stitching approach"),
>  	OPTS_EVSWITCH(&top.evswitch),
>  	OPT_END()
>  	};
> @@ -1612,6 +1618,11 @@ int cmd_top(int argc, const char **argv)
>  		}
>  	}
>  
> +	if (top.stitch_lbr && !(callchain_param.record_mode == CALLCHAIN_LBR)) {
> +		pr_err("Error: --stitch-lbr must be used with --call-graph lbr\n");
> +		goto out_delete_evlist;
> +	}

why is this check not added for script/report/c2c..?

jirka