Date:   Thu, 28 Jan 2021 10:12:09 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jin Yao <yao.jin@...ux.intel.com>
Cc:     jolsa@...nel.org, peterz@...radead.org, mingo@...hat.com,
        alexander.shishkin@...ux.intel.com, Linux-kernel@...r.kernel.org,
        ak@...ux.intel.com, kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH 2/2] perf script: Support dso filter

Em Mon, Jan 25, 2021 at 07:27:50AM +0800, Jin Yao escreveu:
> Other perf tool builtins have already supported dso filter.
> 
> For example,
> perf report --dso, which only considers symbols in these dsos.
> 
> Now dso filter is supported for perf-script.
> 
> root@...-ppc:~# ./perf script --dso "[kernel.kallsyms]"
>             perf 18123 [000] 6142863.075104:          1   cycles:  ffffffff9ca77308 native_write_msr+0x8 ([kernel.kallsyms])
>             perf 18123 [000] 6142863.075107:          1   cycles:  ffffffff9ca77308 native_write_msr+0x8 ([kernel.kallsyms])
>             perf 18123 [000] 6142863.075108:         10   cycles:  ffffffff9ca77308 native_write_msr+0x8 ([kernel.kallsyms])
>             perf 18123 [000] 6142863.075109:        273   cycles:  ffffffff9ca7730a native_write_msr+0xa ([kernel.kallsyms])
>             perf 18123 [000] 6142863.075110:       7684   cycles:  ffffffff9ca3c9c0 native_sched_clock+0x50 ([kernel.kallsyms])
>             perf 18123 [000] 6142863.075112:     213017   cycles:  ffffffff9d765a92 syscall_exit_to_user_mode+0x32 ([kernel.kallsyms])
>             perf 18123 [001] 6142863.075156:          1   cycles:  ffffffff9ca77308 native_write_msr+0x8 ([kernel.kallsyms])
>             perf 18123 [001] 6142863.075158:          1   cycles:  ffffffff9ca77308 native_write_msr+0x8 ([kernel.kallsyms])
>             perf 18123 [001] 6142863.075159:         17   cycles:  ffffffff9ca77308 native_write_msr+0x8 ([kernel.kallsyms])

Applied, and in testing it I noticed this fix was also needed, added
just before it, please ack :-)

- Arnaldo

commit d4b6078bd58b799a8ea2a57842193504c867bee5
Author: Arnaldo Carvalho de Melo <acme@...hat.com>
Date:   Thu Jan 28 09:52:47 2021 -0300

    perf tools: Fix DSO filtering when not finding a map for a sampled address
    
    When we lookup an address and don't find a map we should filter that
    sample if the user specified a list of --dso entries to filter on, fix
    it.
    
    Before:
    
      $ perf script
                 sleep 274800  2843.556162:          1 cycles:u:  ffffffffbb26bff4 [unknown] ([unknown])
                 sleep 274800  2843.556168:          1 cycles:u:  ffffffffbb2b047d [unknown] ([unknown])
                 sleep 274800  2843.556171:          1 cycles:u:  ffffffffbb2706b2 [unknown] ([unknown])
                 sleep 274800  2843.556174:          6 cycles:u:  ffffffffbb2b0267 [unknown] ([unknown])
                 sleep 274800  2843.556176:         59 cycles:u:  ffffffffbb2b03b1 [unknown] ([unknown])
                 sleep 274800  2843.556180:        691 cycles:u:  ffffffffbb26bff4 [unknown] ([unknown])
                 sleep 274800  2843.556189:       9160 cycles:u:      7fa9550eeaa3 __GI___tunables_init+0xf3 (/usr/lib64/ld-2.32.so)
                 sleep 274800  2843.556312:      86937 cycles:u:      7fa9550e157b _dl_lookup_symbol_x+0x4b (/usr/lib64/ld-2.32.so)
      $
    
    So we have some samples we somehow didn't find in a map for, if we now
    do:
    
      $ perf report --stdio --dso /usr/lib64/ld-2.32.so
      # dso: /usr/lib64/ld-2.32.so
      #
      # Total Lost Samples: 0
      #
      # Samples: 8  of event 'cycles:u'
      # Event count (approx.): 96856
      #
      # Overhead  Command  Symbol
      # ........  .......  ........................
      #
          89.76%  sleep    [.] _dl_lookup_symbol_x
           9.46%  sleep    [.] __GI___tunables_init
           0.71%  sleep    [k] 0xffffffffbb26bff4
           0.06%  sleep    [k] 0xffffffffbb2b03b1
           0.01%  sleep    [k] 0xffffffffbb2b0267
           0.00%  sleep    [k] 0xffffffffbb2706b2
           0.00%  sleep    [k] 0xffffffffbb2b047d
      $
    
    After this patch we get the right output with just entries for the DSOs
    specified in --dso:
    
      $ perf report --stdio --dso /usr/lib64/ld-2.32.so
      # dso: /usr/lib64/ld-2.32.so
      #
      # Total Lost Samples: 0
      #
      # Samples: 8  of event 'cycles:u'
      # Event count (approx.): 96856
      #
      # Overhead  Command  Symbol
      # ........  .......  ........................
      #
          89.76%  sleep    [.] _dl_lookup_symbol_x
           9.46%  sleep    [.] __GI___tunables_init
      $
    
      # To display the perf.data header info, please use --header/--header-only options.
      #
    
    Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
    Cc: Andi Kleen <ak@...ux.intel.com>
    Cc: Ingo Molnar <mingo@...hat.com>
    Cc: Jin Yao <yao.jin@...ux.intel.com>
    Cc: Jiri Olsa <jolsa@...nel.org>
    Cc: Kan Liang <kan.liang@...el.com>
    Cc: Namhyung Kim <namhyung@...nel.org>
    Cc: Peter Zijlstra <peterz@...radead.org>
    Fixes: 96415e4d3f5fdf9c ("perf symbols: Avoid unnecessary symbol loading when dso list is specified")
    Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index fbe8578e4c475773..208b6c141d98bb5d 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -692,6 +692,8 @@ int machine__resolve(struct machine *machine, struct addr_location *al,
 		}
 
 		al->sym = map__find_symbol(al->map, al->addr);
+	} else if (symbol_conf.dso_list) {
+		al->filtered |= (1 << HIST_FILTER__DSO);
 	}
 
 	if (symbol_conf.sym_list) {

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