Ivan:
A couple of comments...
On Jan 22, 2010, at 7:33 AM, Ivan Voras wrote:
On 01/22/10 16:10, Ed Schouten wrote:
* Ivan Voras<ivo...@freebsd.org> wrote:
This is a good and useful addition! I think Windows has
implemented a
generalization of this (called "wait objects" or something like
that),
which effectively allows a select()- (or in this case kqueue())-like
syscall to wait on both file descriptors and condvars (as well as
probably other MS-style objects). It's useful for multiplexing
events
for dissimilar sources.
NtWaitForSingleObject(), NtWaitForMultipleObjects(), etc. :-)
Yes, I was thinking about WaitForMultipleObjects() - I sometimes
wished I had it in FreeBSD :)
I think the hackers@ side of the thread is missing the original link
to the patch file offered for review, so here it is:
http://people.freebsd.org/~rrs/kque_umtx.patch
My kqueue-fu level is too low to be really useful here but from what
I've read it looks like a logical and even reasonably clean way of
doing it.
thanks it made sense to me ;-)
If I read the comment at filt_umtxattach() correctly, in the best
case you would need an extension to the kevent structure to add more
fields like data & udata (for passing values back and forth between
userland and kernel). I agree with this - it would be very
convenient for some future purposes (like file modification
notification) if the kernel filter could both accept and return a
struct of data from/to the userland.
Yeah, more arguments inside the kevent would allow me to add the
COND_CV_WAIT* where a lock and condition are passed
in as well... But I was hesitant to add more than was already there
since doing
so would cause ABI ripples that I did not want to face.
I plan on committing this to head if I don't get strong "you idiot you
did it wrong" comments ;-)
R
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Randall Stewart
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