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perf intel-pt: Add support for decoding PSB+ only

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A single q option decodes ip from only FUP/TIP packets. Make it so that
repeating the q option (i.e. qq) decodes only PSB+, getting ip if there
is a FUP packet within PSB+ (i.e. between PSB and PSBEND).

Example:

 $ perf record -e intel_pt//u grep -rI pudding drivers
 [ perf record: Woken up 52 times to write data ]
 [ perf record: Captured and wrote 57.870 MB perf.data ]
 $ time perf script --itrace=bi | wc -l
 58948289

 real    1m23.863s
 user    1m23.251s
 sys     0m7.452s
 $ time perf script --itrace=biq | wc -l
 3385694

 real    0m4.453s
 user    0m4.455s
 sys     0m0.328s
 $ time perf script --itrace=biqq | wc -l
 1883

 real    0m0.047s
 user    0m0.043s
 sys     0m0.009s

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200710151104.15137-13-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Adrian Hunter 2020-07-10 18:11:04 +03:00 committed by Arnaldo Carvalho de Melo
parent 7c1b16ba0e
commit 347a7389a7
2 changed files with 33 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
tools/perf/Documentation/perf-intel-pt.txt
View File

@ -999,6 +999,21 @@ What *will* be decoded with the (single) q option:
Note the q option does not specify what events will be synthesized e.g. the p
option must be used also to show power events.
Repeating the q option (double-q i.e. qq) results in even faster decoding and even
less detail. The decoder decodes only extended PSB (PSB+) packets, getting the
instruction pointer if there is a FUP packet within PSB+ (i.e. between PSB and
PSBEND). Note PSB packets occur regularly in the trace based on the psb_period
config term (refer config terms section). There will be a FUP packet if the
PSB+ occurs while control flow is being traced.
What will *not* be decoded with the qq option:
- everything except instruction pointer associated with PSB packets
What *will* be decoded with the qq option:
- instruction pointer associated with PSB packets
dump option
~~~~~~~~~~~

18
tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
View File

@ -113,6 +113,7 @@ struct intel_pt_decoder {
bool in_psb;
bool hop;
bool hop_psb_fup;
bool leap;
enum intel_pt_param_flags flags;
uint64_t pos;
uint64_t last_ip;
@ -240,6 +241,7 @@ struct intel_pt_decoder *intel_pt_decoder_new(struct intel_pt_params *params)
decoder->return_compression = params->return_compression;
decoder->branch_enable = params->branch_enable;
decoder->hop = params->quick >= 1;
decoder->leap = params->quick >= 2;
decoder->flags = params->flags;
@ -1903,9 +1905,18 @@ static int intel_pt_resample(struct intel_pt_decoder *decoder)
#define HOP_RETURN 2
#define HOP_AGAIN 3
static int intel_pt_scan_for_psb(struct intel_pt_decoder *decoder);
/* Hop mode: Ignore TNT, do not walk code, but get ip from FUPs and TIPs */
static int intel_pt_hop_trace(struct intel_pt_decoder *decoder, bool *no_tip, int *err)
{
/* Leap from PSB to PSB, getting ip from FUP within PSB+ */
if (decoder->leap && !decoder->in_psb && decoder->packet.type != INTEL_PT_PSB) {
*err = intel_pt_scan_for_psb(decoder);
if (*err)
return HOP_RETURN;
}
switch (decoder->packet.type) {
case INTEL_PT_TNT:
return HOP_IGNORE;
@ -2681,6 +2692,7 @@ static int intel_pt_sync(struct intel_pt_decoder *decoder)
decoder->ip = 0;
intel_pt_clear_stack(&decoder->stack);
leap:
err = intel_pt_scan_for_psb(decoder);
if (err)
return err;
@ -2702,6 +2714,12 @@ static int intel_pt_sync(struct intel_pt_decoder *decoder)
decoder->pkt_state = INTEL_PT_STATE_RESAMPLE;
else
decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
} else if (decoder->leap) {
/*
* In leap mode, only PSB+ is decoded, so keeping leaping to the
* next PSB until there is an ip.
*/
goto leap;
} else {
return intel_pt_sync_ip(decoder);
}