Date: Sat, 3 Apr 1999 08:16:08 -0500 (EST) From: "John S. Dyson" <dyson@iquest.net> To: alc@cs.rice.edu (Alan Cox) Cc: current@freebsd.org, luoqi@freebsd.org Subject: Re: SMP users (important) Message-ID: <199904031316.IAA45781@y.dyson.net> In-Reply-To: <19990402124153.H14114@nonpc.cs.rice.edu> from Alan Cox at "Apr 2, 99 12:41:53 pm"
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Alan Cox said: > > I've committed the basic infrastructure to improve TLB management > on SMPs. Translation: this will lead to the elimination of a LOT > of interprocessor interrupts to invalidate TLB entries. I'll be > "turning on" the new mechanisms slowly so we can carefully debug > each step and (hopefully) avoid any problems. > (To the rest of the team, Alan and Luoqi already know my opinion.) I just wanted to "chime in" and say that the new patches are based on a really good concept, and is much cleaner than the previous method. Also, many RISC architectures can utilize this method due to the availability of lots of general registers. (One could go so far as to have the compiler reserve the register.) Non-threaded user mode apps could optionally use the reserved register, but for threaded user mode apps, that reserved register could also be used as a per-thread base pointer. I believe that NT does the above (%fs for X86, and general register for Alpha.) On PPC, there are several local, per-processor registers that one could use (but loading a general register with that per processor register would be needed for access.) Also, since the PPC has lots of registers, one could? permanently reserve one of the general registers (r13?). All in all, this change has the potential for better context switching time (and less memory/better performance for multi-threaded processes.) This is a serious, non-trivial movement in the *right* direction!!! :-). SMP users should be pleased with this movement (I certainly am!!!) -- John | Never try to teach a pig to sing, dyson@iquest.net | it makes one look stupid jdyson@nc.com | and it irritates the pig. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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