diff options
| -rw-r--r-- | docs/tracing.txt | 4 | ||||
| -rw-r--r-- | trace/simple.c | 39 |
2 files changed, 18 insertions, 25 deletions
diff --git a/docs/tracing.txt b/docs/tracing.txt index 453cc4a63d..14db3bffb4 100644 --- a/docs/tracing.txt +++ b/docs/tracing.txt @@ -23,7 +23,7 @@ for debugging, profiling, and observing execution. 4. Pretty-print the binary trace file: - ./simpletrace.py trace-events trace-* + ./scripts/simpletrace.py trace-events trace-* == Trace events == @@ -198,7 +198,7 @@ The "simple" backend produces binary trace files that can be formatted with the simpletrace.py script. The script takes the "trace-events" file and the binary trace: - ./simpletrace.py trace-events trace-12345 + ./scripts/simpletrace.py trace-events trace-12345 You must ensure that the same "trace-events" file was used to build QEMU, otherwise trace event declarations may have changed and output will not be diff --git a/trace/simple.c b/trace/simple.c index ce17d64bd7..74701e3272 100644 --- a/trace/simple.c +++ b/trace/simple.c @@ -53,7 +53,7 @@ enum { uint8_t trace_buf[TRACE_BUF_LEN]; static unsigned int trace_idx; static unsigned int writeout_idx; -static uint64_t dropped_events; +static int dropped_events; static FILE *trace_fp; static char *trace_file_name; @@ -63,7 +63,7 @@ typedef struct { uint64_t timestamp_ns; uint32_t length; /* in bytes */ uint32_t reserved; /* unused */ - uint8_t arguments[]; + uint64_t arguments[]; } TraceRecord; typedef struct { @@ -160,25 +160,22 @@ static gpointer writeout_thread(gpointer opaque) uint8_t bytes[sizeof(TraceRecord) + sizeof(uint64_t)]; } dropped; unsigned int idx = 0; - uint64_t dropped_count; + int dropped_count; size_t unused __attribute__ ((unused)); for (;;) { wait_for_trace_records_available(); - if (dropped_events) { + if (g_atomic_int_get(&dropped_events)) { dropped.rec.event = DROPPED_EVENT_ID, dropped.rec.timestamp_ns = get_clock(); - dropped.rec.length = sizeof(TraceRecord) + sizeof(dropped_events), + dropped.rec.length = sizeof(TraceRecord) + sizeof(uint64_t), dropped.rec.reserved = 0; - while (1) { - dropped_count = dropped_events; - if (g_atomic_int_compare_and_exchange((gint *)&dropped_events, - dropped_count, 0)) { - break; - } - } - memcpy(dropped.rec.arguments, &dropped_count, sizeof(uint64_t)); + do { + dropped_count = g_atomic_int_get(&dropped_events); + } while (!g_atomic_int_compare_and_exchange(&dropped_events, + dropped_count, 0)); + dropped.rec.arguments[0] = dropped_count; unused = fwrite(&dropped.rec, dropped.rec.length, 1, trace_fp); } @@ -213,22 +210,17 @@ int trace_record_start(TraceBufferRecord *rec, TraceEventID event, size_t datasi uint32_t rec_len = sizeof(TraceRecord) + datasize; uint64_t timestamp_ns = get_clock(); - while (1) { - old_idx = trace_idx; + do { + old_idx = g_atomic_int_get(&trace_idx); smp_rmb(); new_idx = old_idx + rec_len; if (new_idx - writeout_idx > TRACE_BUF_LEN) { /* Trace Buffer Full, Event dropped ! */ - g_atomic_int_inc((gint *)&dropped_events); + g_atomic_int_inc(&dropped_events); return -ENOSPC; } - - if (g_atomic_int_compare_and_exchange((gint *)&trace_idx, - old_idx, new_idx)) { - break; - } - } + } while (!g_atomic_int_compare_and_exchange(&trace_idx, old_idx, new_idx)); idx = old_idx % TRACE_BUF_LEN; @@ -275,7 +267,8 @@ void trace_record_finish(TraceBufferRecord *rec) record.event |= TRACE_RECORD_VALID; write_to_buffer(rec->tbuf_idx, &record, sizeof(TraceRecord)); - if ((trace_idx - writeout_idx) > TRACE_BUF_FLUSH_THRESHOLD) { + if ((g_atomic_int_get(&trace_idx) - writeout_idx) + > TRACE_BUF_FLUSH_THRESHOLD) { flush_trace_file(false); } } |