[v5,02/15] block/nvme: Avoid further processing if trace event not enabled

Commit Message

Philippe Mathieu-Daudé Aug. 20, 2020, 4:58 p.m. UTC

Avoid further processing if TRACE_NVME_SUBMIT_COMMAND_RAW is
not enabled. This is an untested intend of performance optimization.

Reviewed-by: Stefan Hajnoczi <[e-mail]>
Signed-off-by: Philippe Mathieu-Daudé <[e-mail]>
---
 block/nvme.c | 3 +++
 1 file changed, 3 insertions(+)

Patch

diff --git a/block/nvme.c b/block/nvme.c
index 2f5e3c2adfa..8c30a5fee28 100644
--- a/block/nvme.c
+++ b/block/nvme.c
@@ -441,6 +441,9 @@  static void nvme_trace_command(const NvmeCmd *cmd)
 {
     int i;
 
+    if (!trace_event_get_state_backends(TRACE_NVME_SUBMIT_COMMAND_RAW)) {
+        return;
+    }
     for (i = 0; i < 8; ++i) {
         uint8_t *cmdp = (uint8_t *)cmd + i * 8;
         trace_nvme_submit_command_raw(cmdp[0], cmdp[1], cmdp[2], cmdp[3],