[PATCH 11/11] perf intel-pt: Add support for decoding PSB+ only

Adrian Hunter
2020-07-09T17:37:38Z

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>
---
tools/perf/Documentation/perf-intel-pt.txt | 3 +++
.../util/intel-pt-decoder/intel-pt-decoder.c | 18 ++++++++++++++++++
2 files changed, 21 insertions(+)

diff --git a/tools/perf/Documentation/perf-intel-pt.txt b/tools/perf/Documentation/perf-intel-pt.txt
index 758295a7e3d6..849474629fe7 100644
--- a/tools/perf/Documentation/perf-intel-pt.txt
+++ b/tools/perf/Documentation/perf-intel-pt.txt
@@ -973,6 +973,9 @@ useful only if the control flow of interest is represented or indicated by FUP,
TIP, TIP.PGE, or TIP.PGD packets. However the q option could be used to find
time ranges that could then be decoded fully using the --time option.

+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).
+

dump option
~~~~~~~~~~~
diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
index ccb204b1a050..697513f35154 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -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);
}
--
2.25.1