nanosleep() replacement Take 2

[Tim Rice]

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.

Something isn't quite right with this version.
When I try this I get
...
scp -l 512 openssh/sshd.o uw711:/tmp
sshd.o                                        100%   84KB  84.1KB/s   00:01
scp -l 256 openssh/sshd.o uw711:/tmp
sshd.o                                        100%   84KB  42.0KB/s   00:02
scp -l 128 openssh/sshd.o uw711:/tmp
sshd.o                                        100%   84KB  42.0KB/s   00:02
scp -l 64 openssh/sshd.o uw711:/tmp
sshd.o                                        100%   84KB  42.0KB/s   00:02
scp -l 8 openssh/sshd.o uw711:/tmp
sshd.o                                        100%   84KB  42.0KB/s   00:02
scp -l 1 openssh/sshd.o uw711:/tmp
sshd.o                                        100%   84KB  42.0KB/s   00:02
...



> 
> 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);
> }
> 
> 

-- 
Tim Rice				Multitalents	(707) 887-1469
tim at multitalents.net