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Improvements to make --bwlimit work better.

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This commit is contained in:
Wayne Davison
2004-05-27 22:09:31 +00:00
parent 3c74c3a358
commit 71e586304b
1 changed files with 38 additions and 6 deletions
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44
io.c
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@@ -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;
tv.tv_usec = bytes_written * 1000 / bwlimit;
tv.tv_sec = tv.tv_usec / 1000000;
tv.tv_usec = tv.tv_usec % 1000000;
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;
}
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) {