Date: Sat, 28 Mar 2009 22:20:35 -0700 From: Julian Elischer <julian@elischer.org> To: David Xu <davidxu@freebsd.org> Cc: Scott Long <scottl@samsco.org>, Sergey Babkin <babkin@verizon.net>, freebsd-hackers@freebsd.org, attilio@freebsd.org, phk@phk.freebsd.dk, freebsd-current@freebsd.org, prashant.vaibhav@gmail.com Subject: Re: Improving the kernel/i386 timecounter performance (GSoC proposal) Message-ID: <49CF0523.8020905@elischer.org> In-Reply-To: <49CEC261.4010803@freebsd.org> References: <11609492.9579.1238167614335.JavaMail.root@vms070.mailsrvcs.net> <49CD0405.1060704@samsco.org> <49CD30E9.7030501@elischer.org> <49CEC261.4010803@freebsd.org>
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David Xu wrote: > Julian Elischer wrote: >> Scott Long wrote: >>> I've been talking about this for years. All I need is help with the >>> VM magic to create the page on fork. I also want two pages, one global >>> for gettimeofday (and any other global data we can think of) and one >>> per-process for static data like getpid/getgid. >> >> interestingly it is even feasible to have a per-thread page.. >> it requires that the scheduler change a page table entry tough. >> > > I will knock his door at midnight if he added such a heavy weight > task in the scheduler, TLB shutdown is horrible, and big code size > squeezing out data from CPU cache is not idea model. > scheduler should be as simple as just a context switching routine. > :-) > > David Xu depends on the hardware. anyhow I was only saying it was possible, not necessarily good or even useful.
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