Date: Fri, 23 Nov 2007 00:24:59 -0800 From: Alfred Perlstein <alfred@freebsd.org> To: dima <_pppp@mail.ru> Cc: arch@freebsd.org Subject: Re: Re[2]: rwlocks, correctness over speed. Message-ID: <20071123082459.GO44563@elvis.mu.org> In-Reply-To: <E1IvIWg-0007u7-00._pppp-mail-ru@f41.mail.ru> References: <20071122195823.GH44563@elvis.mu.org> <E1IvIWg-0007u7-00._pppp-mail-ru@f41.mail.ru>
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* dima <_pppp@mail.ru> [071122 19:20] wrote: > > The current design is probably fast, but incorrect. Writers will be starved even if we deny recursive read-locks. There are 2 ways to fix that: > 1. Forbid recursive read-locks *and* add a flag which would mean "a writer is waiting" (and prohibit future read-lock acquisition). Yes, this would be done later. > 2. Allow recursive read-locks, add the same flag, and add an accounting of all the current readers (so, only recursive read-lock acquisitions would be accepted if a writer is waiting). Probably not going to happen as the extra bookkeeping is supposedly cost prohibitive. -Alfred
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