progress: simplify performance measurement by using getnanotime()
Calculating duration from a single uint64_t is simpler than from a struct timeval. Change throughput measurement from gettimeofday() to getnanotime(). Also calculate misec only if needed, and change integer division to integer multiplication + shift, which should be slightly faster. Signed-off-by: Karsten Blees <blees@dcon.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Karsten Blees committed
Jul 12, 2014 at 02:08 UTC
83d26fa724ef2efbeb332fa3dc92b00c0e579f28
1 file changed
+36
-35
progress.c
+36
-35
@@ -12,13 +12,14 @@
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#include "gettext.h"
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#include "progress.h"
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#include "strbuf.h"
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+#include "trace.h"
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#define TP_IDX_MAX 8
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struct throughput {
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off_t curr_total;
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off_t prev_total;
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- struct timeval prev_tv;
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+ uint64_t prev_ns;
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unsigned int avg_bytes;
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unsigned int avg_misecs;
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unsigned int last_bytes[TP_IDX_MAX];
@@ -127,65 +128,65 @@ static void throughput_string(struct strbuf *buf, off_t total,
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void display_throughput(struct progress *progress, off_t total)
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{
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struct throughput *tp;
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- struct timeval tv;
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- unsigned int misecs;
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+ uint64_t now_ns;
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+ unsigned int misecs, count, rate;
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+ struct strbuf buf = STRBUF_INIT;
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if (!progress)
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return;
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tp = progress->throughput;
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- gettimeofday(&tv, NULL);
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+ now_ns = getnanotime();
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if (!tp) {
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progress->throughput = tp = calloc(1, sizeof(*tp));
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if (tp) {
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tp->prev_total = tp->curr_total = total;
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- tp->prev_tv = tv;
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+ tp->prev_ns = now_ns;
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}
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return;
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}
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tp->curr_total = total;
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+ /* only update throughput every 0.5 s */
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+ if (now_ns - tp->prev_ns <= 500000000)
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+ return;
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+
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/*
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- * We have x = bytes and y = microsecs. We want z = KiB/s:
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+ * We have x = bytes and y = nanosecs. We want z = KiB/s:
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*
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- * z = (x / 1024) / (y / 1000000)
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- * z = x / y * 1000000 / 1024
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- * z = x / (y * 1024 / 1000000)
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+ * z = (x / 1024) / (y / 1000000000)
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+ * z = x / y * 1000000000 / 1024
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+ * z = x / (y * 1024 / 1000000000)
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* z = x / y'
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*
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* To simplify things we'll keep track of misecs, or 1024th of a sec
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* obtained with:
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*
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- * y' = y * 1024 / 1000000
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- * y' = y / (1000000 / 1024)
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- * y' = y / 977
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+ * y' = y * 1024 / 1000000000
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+ * y' = y * (2^10 / 2^42) * (2^42 / 1000000000)
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+ * y' = y / 2^32 * 4398
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+ * y' = (y * 4398) >> 32
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*/
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- misecs = (tv.tv_sec - tp->prev_tv.tv_sec) * 1024;
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- misecs += (int)(tv.tv_usec - tp->prev_tv.tv_usec) / 977;
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+ misecs = ((now_ns - tp->prev_ns) * 4398) >> 32;
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- if (misecs > 512) {
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- struct strbuf buf = STRBUF_INIT;
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- unsigned int count, rate;
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+ count = total - tp->prev_total;
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+ tp->prev_total = total;
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+ tp->prev_ns = now_ns;
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+ tp->avg_bytes += count;
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+ tp->avg_misecs += misecs;
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+ rate = tp->avg_bytes / tp->avg_misecs;
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+ tp->avg_bytes -= tp->last_bytes[tp->idx];
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+ tp->avg_misecs -= tp->last_misecs[tp->idx];
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+ tp->last_bytes[tp->idx] = count;
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+ tp->last_misecs[tp->idx] = misecs;
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+ tp->idx = (tp->idx + 1) % TP_IDX_MAX;
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- count = total - tp->prev_total;
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- tp->prev_total = total;
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- tp->prev_tv = tv;
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- tp->avg_bytes += count;
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- tp->avg_misecs += misecs;
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- rate = tp->avg_bytes / tp->avg_misecs;
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- tp->avg_bytes -= tp->last_bytes[tp->idx];
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- tp->avg_misecs -= tp->last_misecs[tp->idx];
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- tp->last_bytes[tp->idx] = count;
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- tp->last_misecs[tp->idx] = misecs;
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- tp->idx = (tp->idx + 1) % TP_IDX_MAX;
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-
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- throughput_string(&buf, total, rate);
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- strncpy(tp->display, buf.buf, sizeof(tp->display));
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- strbuf_release(&buf);
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- if (progress->last_value != -1 && progress_update)
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- display(progress, progress->last_value, NULL);
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- }
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+ throughput_string(&buf, total, rate);
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+ strncpy(tp->display, buf.buf, sizeof(tp->display));
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+ strbuf_release(&buf);
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+ if (progress->last_value != -1 && progress_update)
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+ display(progress, progress->last_value, NULL);
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}
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int display_progress(struct progress *progress, unsigned n)