Date: Wed, 14 Nov 2007 15:02:05 -0600 From: icantthinkofone <icantthinkofone@charter.net> To: freebsd-hackers@freebsd.org Subject: Re: FreeBSD cache memory allocation Message-ID: <473B624D.5050904@charter.net>
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On Wednesday 14 November 2007 11:11:41 am Rob Belics wrote: > > Someone I can't stand said this about FreeBSD. Though I know C, I don't > > know anything about this and would love to respond. My first thought was > > 'contigmalloc' but I'm not sure it's equivalent. > > [QUOTE]The kernel is really lacking some features. They need a method to > > set precise type of memory cache but BSD doesn't provide way to specify > > memory cache. > > > > For that reason MS has the beautiful > > MmAllocateContigousMemorySpecifyCache()[/QUOTE] For kernel memory on i386 and amd64 in 6.3 and later you can use pmap_change_attr() to adjust the caching mode of memory after you have allocated it. It is best used only with allocations that are a multiple of the page size. -- John Baldwin I posted using the wrong email address above. Apparently the person I was referring to was probably talking about he nvidia issue and I see you, John, are working on that pmap function. One question I have is whether nvidia got themselves into a bind (for lack of a better word) because they wrote their drive using Windows functions but now want FreeBSD to create kernel functions "just like Windows" rather than rewriting their own code. Or is all this truly a lacking feature in FreeBSD?
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