Date: Fri, 12 Jul 2002 16:37:25 -0700 From: Alfred Perlstein <bright@mu.org> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Alan Cox <alc@cs.rice.edu>, cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/kern kern_synch.c src/sys/sys proc.h src/sys/vm vm_zeroidle.c src/sys/i386/i386 genassym.c pmap.c Message-ID: <20020712233725.GQ97638@elvis.mu.org> In-Reply-To: <200207122221.g6CMLZwi063791@apollo.backplane.com> References: <200207122017.g6CKH7fx096339@freefall.freebsd.org> <20020712205516.GD5265@cs.rice.edu> <200207122221.g6CMLZwi063791@apollo.backplane.com>
next in thread | previous in thread | raw e-mail | index | archive | help
* Matthew Dillon <dillon@apollo.backplane.com> [020712 15:48] wrote: > > :I think we should try to take this a step further. Specifically, we > :should recognize when processors are running in user mode in order > :to avoid IPIs on kernel pmap changes. On reentry to the kernel, > :the processor would then do whatever is necessary to resync. If > :too many kernel pmap changes accumulate, then you force a single > :IPI that performs the changes in bulk. > : > :As a start, it would be interesting to know how many IPIs could be > :avoided by such a scheme. > : > :Alan > > We need to run statistics to see where the IPIs are coming from. > A deferral mechanism is only going to be more efficient if its > simple and it might be better to instead just knock down the > subsystems responsible for the majority of IPIs within the > subsystem itself. I'm quite sure Alan's method is described in Vahalia's(sp?) book as an optimization the SVR4.2 (the SVR with mp) took that helped quite a bit. -- -Alfred Perlstein [alfred@freebsd.org] 'Instead of asking why a piece of software is using "1970s technology," start asking why software is ignoring 30 years of accumulated wisdom.' Tax deductible donations for FreeBSD: http://www.freebsdfoundation.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20020712233725.GQ97638>