Ping again. Stephen?
12/05/2021 21:10, Thomas Monjalon: > Ping for v3 > > 12/02/2021 01:21, Honnappa Nagarahalli: > > <snip> > > > > > > > > 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 <step...@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 > > ^^^^^^ may be "implementation" would be > > better? > > > > > > + * 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. > > This looks good. Though the writer starvation is prominent, the reader > > starvation is possible if there is a stream of writers when a writer holds > > the lock. Should we call this out too? > > > > > > > > You did not get review, probably because nobody was Cc'ed. > > > +Cc Honnappa, Joyce and Konstantin
