Re: [PATCH 2/5] progress: return early when in the background
From: Jeff King <hidden>
Date: 2019-03-26 05:38:42
On Mon, Mar 25, 2019 at 11:38:41AM +0100, SZEDER Gábor wrote:
quoted hunk ↗ jump to hunk
diff --git a/progress.c b/progress.c index 02a20e7d58..b57c0dae16 100644 --- a/progress.c +++ b/progress.c@@ -86,28 +86,30 @@ static void display(struct progress *progress, uint64_t n, const char *done) return; progress->last_value = n; + + if (!is_foreground_fd(fileno(stderr)) && !done) { + progress_update = 0; + return; + } +
Moving it here causes a measurable slowdown for: git rev-list --progress=foo --objects --all This function gets called for every single increment of the progress counter. Whereas in its old location:
tp = (progress->throughput) ? progress->throughput->display.buf : "";
eol = done ? done : " \r";
if (progress->total) {
unsigned percent = n * 100 / progress->total;
if (percent != progress->last_percent || progress_update) {
progress->last_percent = percent;
- if (is_foreground_fd(fileno(stderr)) || done) {
- fprintf(stderr, "%s: %3u%% (%"PRIuMAX"/%"PRIuMAX")%s%s",
- progress->title, percent,
- (uintmax_t)n, (uintmax_t)progress->total,
- tp, eol);
- fflush(stderr);
- }It was only triggered when we accumulated enough increments to print. So we save a few instructions in the backgrounded case, but it costs us a lot of extra syscalls in every other case. According to "strace -c", the number of ioctls for that rev-list on git.git went from 6 to 373,461. But more importantly, my best-of-five timings went from 3.340s from 3.407s. That's only 2%, but it would be nice not to pay it if we don't need to. -Peff