Date: Sun, 13 Oct 2002 19:12:10 -0700 From: Wes Peters <wes@softweyr.com> To: Christoph Hellwig <hch@infradead.org> Cc: Matthew Dillon <dillon@apollo.backplane.com>, "Vladimir B. Grebenschikov" <vova@sw.ru>, Nate Lawson <nate@root.org>, arch@FreeBSD.ORG Subject: Re: Database indexes and ram (was Re: using mem above 4Gb was:swapon some regular file) Message-ID: <3DAA27F9.DBDA4EFE@softweyr.com> References: <Pine.BSF.4.21.0210081209010.11243-100000@root.org> <1034105993.913.1.camel@vbook.express.ru> <200210082015.g98KFFrq084625@apollo.backplane.com> <1034109053.913.7.camel@vbook.express.ru> <200210082051.g98KpjU1084793@apollo.backplane.com> <3DA4C271.37AACAA3@softweyr.com> <20021012135245.A16453@infradead.org>
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Christoph Hellwig wrote:
>
> On Wed, Oct 09, 2002 at 04:57:37PM -0700, Wes Peters wrote:
> > Linux solved this problem by refusing to do it. The candidates for DMA
> > transfers include skbufs and buffers from the disk buffer pool, both of
> > which are allocated from the lowest 4GB of physical ram when using PAE
> > mode.
>
> Umm, Linux _does_ DMA into any memory if the NIC/HBA/whatever supports
> it.
And the driver has been modified. There are 3 or 4 drivers that have
been, not a daunting majority by any stretch.
--
"Where am I, and what am I doing in this handbasket?"
Wes Peters Softweyr LLC
wes@softweyr.com http://softweyr.com/
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