Date: Fri, 12 Jul 2002 15:21:35 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Alan Cox <alc@cs.rice.edu> Cc: 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: <200207122221.g6CMLZwi063791@apollo.backplane.com> References: <200207122017.g6CKH7fx096339@freefall.freebsd.org> <20020712205516.GD5265@cs.rice.edu>
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: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.
-Matt
Matthew Dillon
<dillon@backplane.com>
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