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 > + * 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
