From 71e586304be0fcd63313212e30125ff0df56029b Mon Sep 17 00:00:00 2001 From: Wayne Davison Date: Thu, 27 May 2004 22:09:31 +0000 Subject: [PATCH] Improvements to make --bwlimit work better. --- io.c | 44 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 38 insertions(+), 6 deletions(-) diff --git a/io.c b/io.c index c9691ed1..60285656 100644 --- a/io.c +++ b/io.c @@ -47,6 +47,7 @@ static time_t last_io; static int no_flush; extern int bwlimit; +extern size_t bwlimit_writemax; extern int verbose; extern int io_timeout; extern int am_server; @@ -739,22 +740,51 @@ unsigned char read_byte(int f) * use a bit less bandwidth than specified, because it doesn't make up * for slow periods. But arguably this is a feature. In addition, we * ought to take the time used to write the data into account. + * + * During some phases of big transfers (file FOO is uptodate) this is + * called with a small bytes_written every time. As the kernel has to + * round small waits up to guarantee that we actually wait at least the + * requested number of microseconds, this can become grossly inaccurate. + * We therefore keep track of the bytes we've written over time and only + * sleep when the accumulated delay is at least 1 tenth of a second. **/ static void sleep_for_bwlimit(int bytes_written) { - struct timeval tv; + static struct timeval prior_tv; + static long total_written = 0; + struct timeval tv, start_tv; + long elapsed_usec, sleep_usec; + +#define ONE_SEC 1000000L /* # of microseconds in a second */ if (!bwlimit) return; - assert(bytes_written > 0); - assert(bwlimit > 0); + total_written += bytes_written; + + gettimeofday(&start_tv, NULL); + if (prior_tv.tv_sec) { + elapsed_usec = (start_tv.tv_sec - prior_tv.tv_sec) * ONE_SEC + + (start_tv.tv_usec - prior_tv.tv_usec); + total_written -= elapsed_usec * bwlimit / (ONE_SEC/1024); + if (total_written < 0) + total_written = 0; + } - tv.tv_usec = bytes_written * 1000 / bwlimit; - tv.tv_sec = tv.tv_usec / 1000000; - tv.tv_usec = tv.tv_usec % 1000000; + sleep_usec = total_written * (ONE_SEC/1024) / bwlimit; + if (sleep_usec < ONE_SEC / 10) { + prior_tv = start_tv; + return; + } + tv.tv_sec = sleep_usec / ONE_SEC; + tv.tv_usec = sleep_usec % ONE_SEC; select(0, NULL, NULL, NULL, &tv); + + gettimeofday(&prior_tv, NULL); + elapsed_usec = (prior_tv.tv_sec - start_tv.tv_sec) * ONE_SEC + + (prior_tv.tv_usec - start_tv.tv_usec); + total_written = (sleep_usec - elapsed_usec) * bwlimit / (ONE_SEC/1024); } @@ -812,6 +842,8 @@ static void writefd_unbuffered(int fd,char *buf,size_t len) if (FD_ISSET(fd, &w_fds)) { int ret; size_t n = len-total; + if (bwlimit && n > bwlimit_writemax) + n = bwlimit_writemax; ret = write(fd,buf+total,n); if (ret < 0) { -- 2.34.1