Date: Thu, 15 Nov 2007 07:42:15 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: icantthinkofone <icantthinkofone@charter.net> Subject: Re: FreeBSD cache memory allocation Message-ID: <200711150742.16251.jhb@freebsd.org> In-Reply-To: <473B624D.5050904@charter.net> References: <473B624D.5050904@charter.net>
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On Wednesday 14 November 2007 04:02:05 pm icantthinkofone wrote: > 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? It's a lacking feature in FreeBSD. -- John Baldwin
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