[PATCH v7 16/16] progress: simplify performance measurement by using getnanotime()
- From
Karsten Blees <karsten.blees@gmail.com>
- Date
- Jul 1, 2014, 23:05 UTC
- Message-ID
- <53B33EAA.4050407@gmail.com>
- In-Reply-To
- <53B33C05.5090900@gmail.com>
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> --- progress.c | 71 +++++++++++++++++++++++++++++++------------------------------- 1 file changed, 36 insertions(+), 35 deletions(-)
diff --git a/progress.c b/progress.c index 261314e..412e6b1 100644 --- a/progress.c +++ b/progress.c @@ -12,13 +12,14 @@ #include "gettext.h" #include "progress.h" #include "strbuf.h" +#include "trace.h" #define TP_IDX_MAX 8 struct throughput { off_t curr_total; off_t prev_total; - struct timeval prev_tv; + uint64_t prev_ns; unsigned int avg_bytes; unsigned int avg_misecs; unsigned int last_bytes[TP_IDX_MAX]; @@ -127,65 +128,65 @@ static void throughput_string(struct strbuf *buf, off_t total, void display_throughput(struct progress *progress, off_t total) { struct throughput *tp; - struct timeval tv; - unsigned int misecs; + uint64_t now_ns; + unsigned int misecs, count, rate; + struct strbuf buf = STRBUF_INIT; if (!progress) return; tp = progress->throughput; - gettimeofday(&tv, NULL); + now_ns = getnanotime(); if (!tp) { progress->throughput = tp = calloc(1, sizeof(*tp)); if (tp) { tp->prev_total = tp->curr_total = total; - tp->prev_tv = tv; + tp->prev_ns = now_ns; } return; } tp->curr_total = total; + /* only update throughput every 0.5 s */ + if (now_ns - tp->prev_ns <= 500000000) + return; + /* - * We have x = bytes and y = microsecs. We want z = KiB/s: + * We have x = bytes and y = nanosecs. We want z = KiB/s: * - * z = (x / 1024) / (y / 1000000) - * z = x / y * 1000000 / 1024 - * z = x / (y * 1024 / 1000000) + * z = (x / 1024) / (y / 1000000000) + * z = x / y * 1000000000 / 1024 + * z = x / (y * 1024 / 1000000000) * z = x / y' * * To simplify things we'll keep track of misecs, or 1024th of a sec * obtained with: * - * y' = y * 1024 / 1000000 - * y' = y / (1000000 / 1024) - * y' = y / 977 + * y' = y * 1024 / 1000000000 + * y' = y * (2^10 / 2^42) * (2^42 / 1000000000) + * y' = y / 2^32 * 4398 + * y' = (y * 4398) >> 32 */ - misecs = (tv.tv_sec - tp->prev_tv.tv_sec) * 1024; - misecs += (int)(tv.tv_usec - tp->prev_tv.tv_usec) / 977; + misecs = ((now_ns - tp->prev_ns) * 4398) >> 32; - if (misecs > 512) { - struct strbuf buf = STRBUF_INIT; - unsigned int count, rate; + count = total - tp->prev_total; + tp->prev_total = total; + tp->prev_ns = now_ns; + tp->avg_bytes += count; + tp->avg_misecs += misecs; + rate = tp->avg_bytes / tp->avg_misecs; + tp->avg_bytes -= tp->last_bytes[tp->idx]; + tp->avg_misecs -= tp->last_misecs[tp->idx]; + tp->last_bytes[tp->idx] = count; + tp->last_misecs[tp->idx] = misecs; + tp->idx = (tp->idx + 1) % TP_IDX_MAX; - count = total - tp->prev_total; - tp->prev_total = total; - tp->prev_tv = tv; - tp->avg_bytes += count; - tp->avg_misecs += misecs; - rate = tp->avg_bytes / tp->avg_misecs; - tp->avg_bytes -= tp->last_bytes[tp->idx]; - tp->avg_misecs -= tp->last_misecs[tp->idx]; - tp->last_bytes[tp->idx] = count; - tp->last_misecs[tp->idx] = misecs; - tp->idx = (tp->idx + 1) % TP_IDX_MAX; - - throughput_string(&buf, total, rate); - strncpy(tp->display, buf.buf, sizeof(tp->display)); - strbuf_release(&buf); - if (progress->last_value != -1 && progress_update) - display(progress, progress->last_value, NULL); - } + throughput_string(&buf, total, rate); + strncpy(tp->display, buf.buf, sizeof(tp->display)); + strbuf_release(&buf); + if (progress->last_value != -1 && progress_update) + display(progress, progress->last_value, NULL); } int display_progress(struct progress *progress, unsigned n)
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