diff options
| author | Thorsten Blum <thorsten.blum@toblux.com> | 2024-03-29 17:02:30 +0100 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2024-05-13 20:00:57 -0400 |
| commit | 347bd7f072ea8c36e4becf32c76ee7e96bc7b1c3 (patch) | |
| tree | 84fb622b88e32d459772dc5ee58cc64a694a7cd8 /kernel | |
| parent | 33f137143e651321f10eb67ae6404a13bfbf69f8 (diff) | |
| download | linux-stable-347bd7f072ea8c36e4becf32c76ee7e96bc7b1c3.tar.gz linux-stable-347bd7f072ea8c36e4becf32c76ee7e96bc7b1c3.tar.bz2 linux-stable-347bd7f072ea8c36e4becf32c76ee7e96bc7b1c3.zip | |
tracing: Improve benchmark test performance by using do_div()
Partially revert commit d6cb38e10810 ("tracing: Use div64_u64() instead
of do_div()") and use do_div() again to utilize its faster 64-by-32
division compared to the 64-by-64 division done by div64_u64().
Explicitly cast the divisor bm_cnt to u32 to prevent a Coccinelle
warning reported by do_div.cocci. The warning was removed with commit
d6cb38e10810 ("tracing: Use div64_u64() instead of do_div()").
Using the faster 64-by-32 division and casting bm_cnt to u32 is safe
because we return early from trace_do_benchmark() if bm_cnt > UINT_MAX.
This approach is already used twice in trace_do_benchmark() when
calculating the standard deviation:
do_div(stddev, (u32)bm_cnt);
do_div(stddev, (u32)bm_cnt - 1);
Link: https://lore.kernel.org/linux-trace-kernel/20240329160229.4874-2-thorsten.blum@toblux.com
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace_benchmark.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/trace/trace_benchmark.c b/kernel/trace/trace_benchmark.c index 811b08439406..e19c32f2a938 100644 --- a/kernel/trace/trace_benchmark.c +++ b/kernel/trace/trace_benchmark.c @@ -104,7 +104,7 @@ static void trace_do_benchmark(void) stddev = 0; delta = bm_total; - delta = div64_u64(delta, bm_cnt); + do_div(delta, (u32)bm_cnt); avg = delta; if (stddev > 0) { |