nanosleep() replacement Take 2

[Ben Lindstrom]

Mostly -l was designed to allow people to restrict their scp so it does
not take over their bandwidth (mainly dialup and low-end DSL).  The
example was given was a long download that you don't care when it
finishes, just you don't want to choke your small pipe while doing it.

So I doubt it being 100% perfect is a major deal on some platforms.

- Ben

On Tue, 18 Mar 2003, Darren Tucker wrote:

> Gert Doering wrote:
> > Tested on SCO OSR 3.0.  openssh-current (as of right now) with your
> > appended patch.  Configures, compiles, and "scp -l <number>" seems to
> > do things that correlate with the specified number (I assume it's
> > kbit/second and the progress bar is Kbyte/second).
>
> Yes that's the case.
>
> > -l is fairly unprecise, but this is likely due to a fairly slow machine,
> > select()/scheduler granularity, and other things eating CPU.
>
> I saw that too with Tim's function but I was able to get pretty good
> results (5% variance or less from specified bandwidth) on a somewhat
> loaded 170 MHz SPARC.
>
> I suspect there's some cases it doesn't handle correctly (I'm trying to
> find an example).
>
> Would you mind trying the following function for comparison?
>
> 		-Daz.
>
> int nanosleep(const struct timespec *req, struct timespec *rem)
> {
>        int rc;
>        extern int errno;
>        int saverrno;
>        struct timeval tstart, tstop, tremain, time2wait;
>
>        TIMESPEC_TO_TIMEVAL(&time2wait, req)
>
>        gettimeofday(&tstart, NULL);
>        rc = select(0, NULL, NULL, NULL, &time2wait);
>        saverrno = errno;
>        gettimeofday (&tstop, NULL);
>
>        tremain.tv_sec = tstop.tv_sec - tstart.tv_sec - time2wait.tv_sec;
>        tremain.tv_usec = tstop.tv_usec - tstart.tv_usec -
> time2wait.tv_usec;
>        tremain.tv_sec += tremain.tv_usec / 1000000L;
>        tremain.tv_usec %= 1000000L;
>        TIMEVAL_TO_TIMESPEC(&tremain, rem)
>
>        if (rc < 0) {
>                rc = -1;
>                errno = saverrno;
>        }
>        return(rc);
> }
>
> --
> Darren Tucker (dtucker at zip.com.au)
> GPG Fingerprint D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
>     Good judgement comes with experience. Unfortunately, the experience
> usually comes from bad judgement.
>
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