epoch(9) background information?

[Jacques Fourie]

On Tue, Aug 21, 2018 at 8:33 AM, Sebastian Huber <
sebastian.huber at embedded-brains.de> wrote:

> Hello,
>
> I update currently a port of the FreeBSD network stack, etc. to the
> real-time operating system RTEMS from the head version at 2017-04-04 to the
> head version of today. I noticed that some read-write locks are replaced by
> a relatively new stuff called EPOCH(9). Is there some background
> information available for this? The man page is a bit vague and searching
> for something named epoch on the internet is not really great. For example,
> what is the motivation for this change? How is this related to
> read-copy-update (RCU)?
>
> --
> Sebastian Huber, embedded brains GmbH
>
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>
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Additional information is available here : http://concurrencykit.org/pr
esentations/ebr.pdf. The way I understand it is that it is mostly used in
place of read locks to provide liveness guarantees without using atomics.
Additional detail is available in the commit messages. As an example see
r333813 for some performance data.