Date: Sat, 13 Jul 1996 23:29:08 -0600 From: Warner Losh <imp@village.org> To: Bruce Evans <bde@zeta.org.au> Cc: matt@lkg.dec.com, freebsd-hackers@FreeBSD.ORG, tech-kern@netbsd.org Subject: Re: Some interesting papers on BSD ... Message-ID: <199607140529.XAA07492@rover.village.org> In-Reply-To: Your message of Tue, 09 Jul 1996 11:31:59 %2B1000
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: spl is probably fundamentally wrong for SMP. I haven't thought much : about what to use instead. The Solbourne people might disagree with you. As might the VMS Digitial people. Both groups used a scheme where you would raise the spl *AND* grab access locks to data structures (I think the latter was optional on VMS depending on the, as I recall it, NCPU SYSGEN parameter). Both these systems used fairly fine grained locking and took a lot of time to get right and robust. Sun, when they were writing Solaris, is rumored to have produced "warlock." This program would go through all your sources and warn of potential deadlock situations in them. They never released it as they considered it a competitive advantage to them... There is no other way to do MP synchronization than using some kind of explicit locking that doesn't rely on the interrupt level.[*] Warner [*] Or I'd like ot be pointed at something that proves this statement wrong.
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