>Synopsis: race between kqueue vnode note for writes triggering reads on a
>pre-mmapped file segment
>Category: kernel
>Environment:
System : OpenBSD 5.9
Details : OpenBSD 5.9 (GENERIC) #1761: Fri Feb 26 01:15:04 MST 2016
d
Wait, would reading back over the mapping create a copy of the page?
Even if the contents are identical, it would still be the write of a
copy-on-write, I am guessing. I can write into a separate buffer and
copy it into the mapping only if there is a mismatch, or I can use a
periodic fork. That's
Ben Woolley wrote:
> Do the updates of the mmap happen in the order that writes are made?
> If so, I could at least tell when coherence was reached.
>
> But it isn't a huge deal. The main purpose was to be able to share
> memory between workers, and I can just do a read() into the shared
> memory
Ben Woolley wrote:
> On both UFS and tmpfs, if you watch for updates to the file with
> kqueue, and pre-mmap a segment of the file, using the kqueue data to
> notify of updates to the file crusor, and append the file in a
> separate process, the written contents will populate AFTER the kqueue
>
>Synopsis: race between kqueue vnode note for writes triggering reads on a
>pre-mmapped file segment
>Category: kernel
>Environment:
System : OpenBSD 5.9
Details : OpenBSD 5.9 (GENERIC) #1761: Fri Feb 26 01:15:04 MST 2016
dera...@amd64.openbsd.org:/usr/src/sys/arch/amd64/com
