Date: Fri, 21 Jul 2000 11:50:35 -0700 From: Lars Eggert <larse@ISI.EDU> To: cort@fsmlabs.com Cc: Alan Cox <alc@cs.rice.edu>, hackers@freebsd.org Subject: Re: clearing pages in the idle loop Message-ID: <39789B7B.FB8F86ED@isi.edu> References: <20000719234124.H14543@cs.rice.edu> <39788E48.60F8A59F@isi.edu> <20000721121457.R26237@medea.fsmlabs.com>
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cort@fsmlabs.com wrote: > We started losing performance with the idle page clearing so > I've disabled it and haven't done much with it in quite a while. The code > has fallen into disrepair and some has been removed in the latest > versions. I'd suggest looking at the early 2.3.x and 2.2.1[23] series of > Linux kernels. That's where it was doing its best. Thanks. I'll get that version. > How do you keep track of what parts of a page are used? In Linux I was > just pulling pages off the free-list and zero-ing them. Do you have a > bitmap of used regions within pages on BSD? My mistake. FreeBSD zeroes the whole page as well. I traced through the code incorrectly. > I wanted a few bits for each page to describe its state: zero'd, > non-zero'd, busy being zero'd. It would have taken some changes to the > non-arch Linux code to do that and at the time we were moving to a more > stable tree so I didn't continue with it. It sounds as though you have a > framework for doing that sort of thing (and more) with BSD. Can you send > me a pointer to the sources you're using? I'd like to look into it. I'm running FreeBSD-stable right now, though I may switch to -current if I get promising results, to make it easier to merge. (There is a web interface to the FreeBSD CVS tree at http://www.freebsd.org/support.html#cvs). FYI, I'm interest in this for my thesis, which consists of two parts: (1) utilizing idle resources (cpu, memory, disk/network I/O, disk/memory space) for non-interfering background processing (i.e. run processes/threads using *only* idle capacities); and (2) to use that mechanism for speculative techniques. Lars -- Lars Eggert <larse@isi.edu> Information Sciences Institute http://www.isi.edu/larse/ University of Southern California To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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