Jeff Trawick wrote:
Brian Pane <[EMAIL PROTECTED]> writes:
The logic for setting the nonblocking state looks like this:
- fcntl(sd, F_GETFL, ...) to get the current flags on the socket descriptor - OR the flags with O_NONBLOCK or O_NDELAY or O_FNDELAY, depending on the OS. - fcntl(sd, F_SETFL, flags) to set the new flags.
According to the profiler data, the F_GETFL fcntl operation is more expensive than the F_SETFL one.
Dumb question... Have you tried commenting out the F_GETFL to see what happens? Does the F_SETFL suddenly get more expensive?
What I wonder about is if there is some stream operation that has to be performed on one of these first socket calls such that if you remove F_GETFL it just makes the next call more expensive.
I finally had a chance to look into this just now, but in the latest round of profiling the F_GETFL operation accounts for only 7% of the run time of sononblock(), with F_SETFL comprising the other 93%. Not coincidentally, the test machine has been updated with dozens of Solaris 8 patches since the last round of tests. As far as I can tell, a function called _so_getsockopt() in libsocket.so, which is called internally during fcntl(F_GETFL), seems to have gotten faster in one of these patches (possibly patch 111327-03).
Thus there's probably no longer a need to optimize away the F_GETFL for Solaris.
The biggest remaining problem in sononblock() is that fcntl on Solaris calls fstat64 to figure out if its argument is a socket, and fstat64 takes a while.
--Brian
