Commit a65988a0 authored by Johannes Thumshirn's avatar Johannes Thumshirn Committed by Jens Axboe
Browse files

blktrace: only calculate trace length once 



De-duplicate the calculation of the trace length instead of doing the
calculation twice, once for calling trace_buffer_lock_reserve() and once
for calling relay_reserve().

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDamien Le Moal <dlemoal@kernel.org>
Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 5c5028ee

kernel/trace/blktrace.c

+8 −6
Original line number Diff line number Diff line
@@ -76,13 +76,14 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action, 
	int cpu = smp_processor_id();

	bool blk_tracer = blk_tracer_enabled;

	ssize_t cgid_len = cgid ? sizeof(cgid) : 0;

	size_t trace_len;



	trace_len = sizeof(*t) + cgid_len + len;

	if (blk_tracer) {

		buffer = blk_tr->array_buffer.buffer;

		trace_ctx = tracing_gen_ctx_flags(0);

		event = trace_buffer_lock_reserve(buffer, TRACE_BLK,

						  sizeof(*t) + len + cgid_len,

						  trace_ctx);

						  trace_len, trace_ctx);

		if (!event)

			return;

		t = ring_buffer_event_data(event);
@@ -92,7 +93,7 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action, 
	if (!bt->rchan)

		return;



	t = relay_reserve(bt->rchan, sizeof(*t) + len + cgid_len);

	t = relay_reserve(bt->rchan, trace_len);

	if (t) {

		t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;

		t->time = ktime_to_ns(ktime_get());
@@ -228,6 +229,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, 
	bool blk_tracer = blk_tracer_enabled;

	ssize_t cgid_len = cgid ? sizeof(cgid) : 0;

	const enum req_op op = opf & REQ_OP_MASK;

	size_t trace_len;



	if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))

		return;
@@ -250,14 +252,14 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, 
		return;

	cpu = raw_smp_processor_id();



	trace_len = sizeof(*t) + pdu_len + cgid_len;

	if (blk_tracer) {

		tracing_record_cmdline(current);



		buffer = blk_tr->array_buffer.buffer;

		trace_ctx = tracing_gen_ctx_flags(0);

		event = trace_buffer_lock_reserve(buffer, TRACE_BLK,

						  sizeof(*t) + pdu_len + cgid_len,

						  trace_ctx);

						  trace_len, trace_ctx);

		if (!event)

			return;

		t = ring_buffer_event_data(event);
@@ -273,7 +275,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, 
	 * from coming in and stepping on our toes.

	 */

	local_irq_save(flags);

	t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len + cgid_len);

	t = relay_reserve(bt->rchan, trace_len);

	if (t) {

		sequence = per_cpu_ptr(bt->sequence, cpu);