Zero-copy network transmission with io

Zero-copy network transmission with io_uring

Posted Dec 31, 2021 17:07 UTC (Fri) by Sesse (subscriber, #53779)
In reply to: Zero-copy network transmission with io_uring by Wol
Parent article: Zero-copy network transmission with io_uring

FreeBSD (possibly some of the other BSDs?) have a zerocopy mechanism that flags the page as COW in the MMU (relieving userspace of the need to know, so you can essentially always use zerocopy), but of course then you pay a price if you don't leave it alone for long enough afterwards.

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Zero-copy network transmission with io_uring

Posted Jan 1, 2022 16:55 UTC (Sat) by shemminger (subscriber, #5739) [Link]

Many years ago there were experiments with COW and networking. See Intel paper at Ottawa Linux Symposium.
The experiment concluded that COW was a slower because the cost of acquiring locks to invalidate the TLB entries on other CPU's exceeded the cost of the copy. The parameters might now with larger sends (64K or more) and huge pages. Definitely worth investigating but the VM overhead is significant.