[PATCH 10/11] perf intel-pt: Add support for decoding FUP/TIP only

Adrian Hunter
2020-07-09T17:37:34Z

Use the new itrace 'q' option to add support for a mode of decoding that
ignores TNT, does not walk object code, but gets the ip from FUP and TIP
packets.

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

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
tools/perf/Documentation/perf-intel-pt.txt | 8 +
.../util/intel-pt-decoder/intel-pt-decoder.c | 167 +++++++++++++++++-
.../util/intel-pt-decoder/intel-pt-decoder.h | 1 +
tools/perf/util/intel-pt.c | 6 +-
4 files changed, 177 insertions(+), 5 deletions(-)

diff --git a/tools/perf/Documentation/perf-intel-pt.txt b/tools/perf/Documentation/perf-intel-pt.txt
index 9a90e2db4e4a..758295a7e3d6 100644
--- a/tools/perf/Documentation/perf-intel-pt.txt
+++ b/tools/perf/Documentation/perf-intel-pt.txt
@@ -825,6 +825,7 @@ The letters are:
l synthesize last branch entries (use with i or x)
L synthesize last branch entries on existing event records
s skip initial number of events
+ q quicker (less detailed) decoding

"Instructions" events look like they were recorded by "perf record -e
instructions".
@@ -965,6 +966,13 @@ at the beginning. This is useful to ignore initialization code.

skips the first million instructions.

+The q option does not decode TNT packets, and does not walk object code, but
+gets the ip from FUP and TIP packets. The q option can be used with the b and i
+options but the period is not used. The q option decodes more quickly, but is
+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.
+

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 7ffcbd6fcd1a..ccb204b1a050 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -55,6 +55,7 @@ enum intel_pt_pkt_state {
INTEL_PT_STATE_TIP_PGD,
INTEL_PT_STATE_FUP,
INTEL_PT_STATE_FUP_NO_TIP,
+ INTEL_PT_STATE_RESAMPLE,
};

static inline bool intel_pt_sample_time(enum intel_pt_pkt_state pkt_state)
@@ -65,6 +66,7 @@ static inline bool intel_pt_sample_time(enum intel_pt_pkt_state pkt_state)
case INTEL_PT_STATE_ERR_RESYNC:
case INTEL_PT_STATE_IN_SYNC:
case INTEL_PT_STATE_TNT_CONT:
+ case INTEL_PT_STATE_RESAMPLE:
return true;
case INTEL_PT_STATE_TNT:
case INTEL_PT_STATE_TIP:
@@ -109,6 +111,8 @@ struct intel_pt_decoder {
bool fixup_last_mtc;
bool have_last_ip;
bool in_psb;
+ bool hop;
+ bool hop_psb_fup;
enum intel_pt_param_flags flags;
uint64_t pos;
uint64_t last_ip;
@@ -235,6 +239,7 @@ struct intel_pt_decoder *intel_pt_decoder_new(struct intel_pt_params *params)
decoder->data = params->data;
decoder->return_compression = params->return_compression;
decoder->branch_enable = params->branch_enable;
+ decoder->hop = params->quick >= 1;

decoder->flags = params->flags;

@@ -275,6 +280,9 @@ struct intel_pt_decoder *intel_pt_decoder_new(struct intel_pt_params *params)
intel_pt_log("timestamp: tsc_ctc_mult %u\n", decoder->tsc_ctc_mult);
intel_pt_log("timestamp: tsc_slip %#x\n", decoder->tsc_slip);

+ if (decoder->hop)
+ intel_pt_log("Hop mode: decoding FUP and TIPs, but not TNT\n");
+
return decoder;
}

@@ -1730,8 +1738,14 @@ static int intel_pt_walk_psbend(struct intel_pt_decoder *decoder)

case INTEL_PT_FUP:
decoder->pge = true;
- if (decoder->packet.count)
+ if (decoder->packet.count) {
intel_pt_set_last_ip(decoder);
+ if (decoder->hop) {
+ /* Act on FUP at PSBEND */
+ decoder->ip = decoder->last_ip;
+ decoder->hop_psb_fup = true;
+ }
+ }
break;

case INTEL_PT_MODE_TSX:
@@ -1875,6 +1889,118 @@ static int intel_pt_walk_fup_tip(struct intel_pt_decoder *decoder)
}
}

+static int intel_pt_resample(struct intel_pt_decoder *decoder)
+{
+ decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
+ decoder->state.type = INTEL_PT_INSTRUCTION;
+ decoder->state.from_ip = decoder->ip;
+ decoder->state.to_ip = 0;
+ return 0;
+}
+
+#define HOP_PROCESS 0
+#define HOP_IGNORE 1
+#define HOP_RETURN 2
+#define HOP_AGAIN 3
+
+/* 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)
+{
+ switch (decoder->packet.type) {
+ case INTEL_PT_TNT:
+ return HOP_IGNORE;
+
+ case INTEL_PT_TIP_PGD:
+ if (!decoder->packet.count)
+ return HOP_IGNORE;
+ intel_pt_set_ip(decoder);
+ decoder->state.type |= INTEL_PT_TRACE_END;
+ decoder->state.from_ip = 0;
+ decoder->state.to_ip = decoder->ip;
+ return HOP_RETURN;
+
+ case INTEL_PT_TIP:
+ if (!decoder->packet.count)
+ return HOP_IGNORE;
+ intel_pt_set_ip(decoder);
+ decoder->state.type = INTEL_PT_INSTRUCTION;
+ decoder->state.from_ip = decoder->ip;
+ decoder->state.to_ip = 0;
+ return HOP_RETURN;
+
+ case INTEL_PT_FUP:
+ if (!decoder->packet.count)
+ return HOP_IGNORE;
+ intel_pt_set_ip(decoder);
+ if (intel_pt_fup_event(decoder))
+ return HOP_RETURN;
+ if (!decoder->branch_enable)
+ *no_tip = true;
+ if (*no_tip) {
+ decoder->state.type = INTEL_PT_INSTRUCTION;
+ decoder->state.from_ip = decoder->ip;
+ decoder->state.to_ip = 0;
+ return HOP_RETURN;
+ }
+ *err = intel_pt_walk_fup_tip(decoder);
+ if (!*err)
+ decoder->pkt_state = INTEL_PT_STATE_RESAMPLE;
+ return HOP_RETURN;
+
+ case INTEL_PT_PSB:
+ decoder->last_ip = 0;
+ decoder->have_last_ip = true;
+ decoder->hop_psb_fup = false;
+ *err = intel_pt_walk_psbend(decoder);
+ if (*err == -EAGAIN)
+ return HOP_AGAIN;
+ if (*err)
+ return HOP_RETURN;
+ if (decoder->hop_psb_fup) {
+ decoder->hop_psb_fup = false;
+ decoder->state.type = INTEL_PT_INSTRUCTION;
+ decoder->state.from_ip = decoder->ip;
+ decoder->state.to_ip = 0;
+ return HOP_RETURN;
+ }
+ if (decoder->cbr != decoder->cbr_seen) {
+ decoder->state.type = 0;
+ return HOP_RETURN;
+ }
+ return HOP_IGNORE;
+
+ case INTEL_PT_BAD:
+ case INTEL_PT_PAD:
+ case INTEL_PT_TIP_PGE:
+ case INTEL_PT_TSC:
+ case INTEL_PT_TMA:
+ case INTEL_PT_MODE_EXEC:
+ case INTEL_PT_MODE_TSX:
+ case INTEL_PT_MTC:
+ case INTEL_PT_CYC:
+ case INTEL_PT_VMCS:
+ case INTEL_PT_PSBEND:
+ case INTEL_PT_CBR:
+ case INTEL_PT_TRACESTOP:
+ case INTEL_PT_PIP:
+ case INTEL_PT_OVF:
+ case INTEL_PT_MNT:
+ case INTEL_PT_PTWRITE:
+ case INTEL_PT_PTWRITE_IP:
+ case INTEL_PT_EXSTOP:
+ case INTEL_PT_EXSTOP_IP:
+ case INTEL_PT_MWAIT:
+ case INTEL_PT_PWRE:
+ case INTEL_PT_PWRX:
+ case INTEL_PT_BBP:
+ case INTEL_PT_BIP:
+ case INTEL_PT_BEP:
+ case INTEL_PT_BEP_IP:
+ default:
+ return HOP_PROCESS;
+ }
+}
+
static int intel_pt_walk_trace(struct intel_pt_decoder *decoder)
{
bool no_tip = false;
@@ -1885,6 +2011,19 @@ static int intel_pt_walk_trace(struct intel_pt_decoder *decoder)
if (err)
return err;
next:
+ if (decoder->hop) {
+ switch (intel_pt_hop_trace(decoder, &no_tip, &err)) {
+ case HOP_IGNORE:
+ continue;
+ case HOP_RETURN:
+ return err;
+ case HOP_AGAIN:
+ goto next;
+ default:
+ break;
+ }
+ }
+
switch (decoder->packet.type) {
case INTEL_PT_TNT:
if (!decoder->packet.count)
@@ -1914,6 +2053,12 @@ static int intel_pt_walk_trace(struct intel_pt_decoder *decoder)
decoder->state.from_ip = 0;
decoder->state.to_ip = decoder->ip;
decoder->state.type |= INTEL_PT_TRACE_BEGIN;
+ /*
+ * In hop mode, resample to get the to_ip as an
+ * "instruction" sample.
+ */
+ if (decoder->hop)
+ decoder->pkt_state = INTEL_PT_STATE_RESAMPLE;
return 0;
}

@@ -2033,7 +2178,7 @@ static int intel_pt_walk_trace(struct intel_pt_decoder *decoder)

case INTEL_PT_MODE_TSX:
/* MODE_TSX need not be followed by FUP */
- if (!decoder->pge) {
+ if (!decoder->pge || decoder->in_psb) {
intel_pt_update_in_tx(decoder);
break;
}
@@ -2424,7 +2569,11 @@ static int intel_pt_sync_ip(struct intel_pt_decoder *decoder)
if (err)
return err;

- decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
+ /* In hop mode, resample to get the to_ip as an "instruction" sample */
+ if (decoder->hop)
+ decoder->pkt_state = INTEL_PT_STATE_RESAMPLE;
+ else
+ decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
decoder->overflow = false;

decoder->state.from_ip = 0;
@@ -2545,7 +2694,14 @@ static int intel_pt_sync(struct intel_pt_decoder *decoder)

if (decoder->ip) {
decoder->state.type = 0; /* Do not have a sample */
- decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
+ /*
+ * In hop mode, resample to get the PSB FUP ip as an
+ * "instruction" sample.
+ */
+ if (decoder->hop)
+ decoder->pkt_state = INTEL_PT_STATE_RESAMPLE;
+ else
+ decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
} else {
return intel_pt_sync_ip(decoder);
}
@@ -2609,6 +2765,9 @@ const struct intel_pt_state *intel_pt_decode(struct intel_pt_decoder *decoder)
if (err == -EAGAIN)
err = intel_pt_walk_trace(decoder);
break;
+ case INTEL_PT_STATE_RESAMPLE:
+ err = intel_pt_resample(decoder);
+ break;
default:
err = intel_pt_bug(decoder);
break;
diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.h b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.h
index e289e463d635..8645fc265481 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.h
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.h
@@ -250,6 +250,7 @@ struct intel_pt_params {
uint32_t tsc_ctc_ratio_n;
uint32_t tsc_ctc_ratio_d;
enum intel_pt_param_flags flags;
+ unsigned int quick;
};

struct intel_pt_decoder;
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 597120dd6b77..93659e738d40 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1036,6 +1036,7 @@ static struct intel_pt_queue *intel_pt_alloc_queue(struct intel_pt *pt,
params.mtc_period = intel_pt_mtc_period(pt);
params.tsc_ctc_ratio_n = pt->tsc_ctc_ratio_n;
params.tsc_ctc_ratio_d = pt->tsc_ctc_ratio_d;
+ params.quick = pt->synth_opts.quick;

if (pt->filts.cnt > 0)
params.pgd_ip = intel_pt_pgd_ip;
@@ -1429,7 +1430,10 @@ static int intel_pt_synth_instruction_sample(struct intel_pt_queue *ptq)

sample.id = ptq->pt->instructions_id;
sample.stream_id = ptq->pt->instructions_id;
- sample.period = ptq->state->tot_insn_cnt - ptq->last_insn_cnt;
+ if (pt->synth_opts.quick)
+ sample.period = 1;
+ else
+ sample.period = ptq->state->tot_insn_cnt - ptq->last_insn_cnt;

sample.cyc_cnt = ptq->ipc_cyc_cnt - ptq->last_in_cyc_cnt;
if (sample.cyc_cnt) {
--
2.25.1