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trace: Clean up the "try to update atomic until it worked" loops

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Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Harsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Markus Armbruster 2013-01-25 16:43:39 +01:00 committed by Stefan Hajnoczi
parent e722d705ae
commit b6b2c96280
1 changed files with 5 additions and 13 deletions
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18
trace/simple.c
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@ -171,13 +171,10 @@ static gpointer writeout_thread(gpointer opaque)
dropped.rec.timestamp_ns = get_clock();
dropped.rec.length = sizeof(TraceRecord) + sizeof(uint64_t),
dropped.rec.reserved = 0;
while (1) {
do {
dropped_count = g_atomic_int_get(&dropped_events);
if (g_atomic_int_compare_and_exchange(&dropped_events,
dropped_count, 0)) {
break;
}
}
} 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);
}
@ -213,7 +210,7 @@ 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) {
do {
old_idx = g_atomic_int_get(&trace_idx);
smp_rmb();
new_idx = old_idx + rec_len;
@ -223,12 +220,7 @@ int trace_record_start(TraceBufferRecord *rec, TraceEventID event, size_t datasi
g_atomic_int_inc(&dropped_events);
return -ENOSPC;
}
if (g_atomic_int_compare_and_exchange(&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;