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Subject[PATCH 2/9] perf intel-pt: Fix sync_switch
Date
sync_switch is a facility to synchronize decoding more closely with the
point in the kernel when the context actually switched. The flag when
sync_switch is enabled was global to the decoding, whereas it is really
specific to the CPU. The trace data for different CPUs is put on different
queues, so add sync_switch to the intel_pt_queue structure and use that in
preference to the global setting in the intel_pt structure. That fixes
problems decoding one CPU's trace because sync_switch was disabled on a
different CPU's queue.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: <stable@vger.kernel.org>
---
tools/perf/util/intel-pt.c | 32 +++++++++++++++++++++++++-------
1 file changed, 25 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 4a7746249999..0979a6e8b2b7 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -143,6 +143,7 @@ struct intel_pt_queue {
bool stop;
bool step_through_buffers;
bool use_buffer_pid_tid;
+ bool sync_switch;
pid_t pid, tid;
int cpu;
int switch_state;
@@ -963,10 +964,12 @@ static int intel_pt_setup_queue(struct intel_pt *pt,
if (pt->timeless_decoding || !pt->have_sched_switch)
ptq->use_buffer_pid_tid = true;
}
+
+ ptq->sync_switch = pt->sync_switch;
}

if (!ptq->on_heap &&
- (!pt->sync_switch ||
+ (!ptq->sync_switch ||
ptq->switch_state != INTEL_PT_SS_EXPECTING_SWITCH_EVENT)) {
const struct intel_pt_state *state;
int ret;
@@ -1549,7 +1552,7 @@ static int intel_pt_sample(struct intel_pt_queue *ptq)
if (pt->synth_opts.last_branch)
intel_pt_update_last_branch_rb(ptq);

- if (!pt->sync_switch)
+ if (!ptq->sync_switch)
return 0;

if (intel_pt_is_switch_ip(ptq, state->to_ip)) {
@@ -1630,6 +1633,21 @@ static u64 intel_pt_switch_ip(struct intel_pt *pt, u64 *ptss_ip)
return switch_ip;
}

+static void intel_pt_enable_sync_switch(struct intel_pt *pt)
+{
+ unsigned int i;
+
+ pt->sync_switch = true;
+
+ for (i = 0; i < pt->queues.nr_queues; i++) {
+ struct auxtrace_queue *queue = &pt->queues.queue_array[i];
+ struct intel_pt_queue *ptq = queue->priv;
+
+ if (ptq)
+ ptq->sync_switch = true;
+ }
+}
+
static int intel_pt_run_decoder(struct intel_pt_queue *ptq, u64 *timestamp)
{
const struct intel_pt_state *state = ptq->state;
@@ -1646,7 +1664,7 @@ static int intel_pt_run_decoder(struct intel_pt_queue *ptq, u64 *timestamp)
if (pt->switch_ip) {
intel_pt_log("switch_ip: %"PRIx64" ptss_ip: %"PRIx64"\n",
pt->switch_ip, pt->ptss_ip);
- pt->sync_switch = true;
+ intel_pt_enable_sync_switch(pt);
}
}
}
@@ -1662,9 +1680,9 @@ static int intel_pt_run_decoder(struct intel_pt_queue *ptq, u64 *timestamp)
if (state->err) {
if (state->err == INTEL_PT_ERR_NODATA)
return 1;
- if (pt->sync_switch &&
+ if (ptq->sync_switch &&
state->from_ip >= pt->kernel_start) {
- pt->sync_switch = false;
+ ptq->sync_switch = false;
intel_pt_next_tid(pt, ptq);
}
if (pt->synth_opts.errors) {
@@ -1690,7 +1708,7 @@ static int intel_pt_run_decoder(struct intel_pt_queue *ptq, u64 *timestamp)
state->timestamp, state->est_timestamp);
ptq->timestamp = state->est_timestamp;
/* Use estimated TSC in unknown switch state */
- } else if (pt->sync_switch &&
+ } else if (ptq->sync_switch &&
ptq->switch_state == INTEL_PT_SS_UNKNOWN &&
intel_pt_is_switch_ip(ptq, state->to_ip) &&
ptq->next_tid == -1) {
@@ -1837,7 +1855,7 @@ static int intel_pt_sync_switch(struct intel_pt *pt, int cpu, pid_t tid,
return 1;

ptq = intel_pt_cpu_to_ptq(pt, cpu);
- if (!ptq)
+ if (!ptq || !ptq->sync_switch)
return 1;

switch (ptq->switch_state) {
--
1.9.1
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