ALS: Linux interprocess communication and kdbus

Posted Jun 7, 2013 5:27 UTC (Fri) by swetland (guest, #63414)
Parent article: ALS: Linux interprocess communication and kdbus

pmem is obsolete and I'm not entirely sure why it found its way into staging in the first place.

ashmem provides anonymous, shareable (via fd passing and mmap) memory without requiring /tmp, without having to worry about cleaning up after processes that leave stuff in /tmp, etc. It also provides a mechanism for processes to indicate which chunks of these regions may be reclaimed by the kernel in low memory situations via the unpin/pin mechanism. Android relies on it in a number of places and that is not likely to change, but if all the same semantics were provided via a slightly different mechanism, it could be migrated to.

ALS: Linux interprocess communication and kdbus

Posted Jun 14, 2013 19:51 UTC (Fri) by jstultz (subscriber, #212) [Link]

Yea, I don't know why he brought up pmem. And its not in staging (as far as I'm aware).

And yea, I also don't understand the "lazy" characterization of ashmem either.

I'm hoping the volatile range work will provide the same functionality as pinning/unpinning (which I think is a really cool feature of ashmem) in a more generic way.

But there is still the need for getting passable fds to anonymous memory without having a tmpfs mount. And until that is solved I suspect we'll have to keep ashmem (although with the pin/unpin logic removed, it will be much simplified).