Re: [dpdk-dev] [PATCH v2] eal/rwlock: add note about writer starvation

[Thomas Monjalon <thomas@monjalon.net>]

14/01/2021 17:55, Stephen Hemminger:
> The implementation of reader/writer locks in DPDK (from first release)
> is simple and fast. But it can lead to writer starvation issues.
> 
> It is not easy to fix this without changing ABI and potentially
> breaking customer applications that are expect the unfair behavior.

typo: "are expect"

> The wikipedia page on reader-writer problem has a similar example
> which summarizes the problem pretty well.

Maybe add the URL in the commit message?

> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
> --- a/lib/librte_eal/include/generic/rte_rwlock.h
> +++ b/lib/librte_eal/include/generic/rte_rwlock.h
> + * Note: This version of reader/writer locks is not fair because
> + * readers do not block for pending writers. A stream of readers can
> + * subsequently lock out all potential writers and starve them.
> + * This is because after the first reader locks the resource,
> + * no writer can lock it. The writer will only be able to get the lock
> + * when it will only be released by the last reader.

You did not get review, probably because nobody was Cc'ed.
+Cc Honnappa, Joyce and Konstantin