Re: 2.4.13-pre5-aa1 O_DIRECT drastic HIGHMEM performance hit

[Andrea Arcangeli]

On Thu, Oct 25, 2001 at 11:57:08AM -0500, Marvin Justice wrote:
> Are we stuck with a low mem configuration or are there workarounds that
> would allow us to stick with the initial 2GB of RAM and still get ~200
> MB/sec.

the problem you seen isn't specific to O_DIRECT. This should solve your
problem (not just for O_DIRECT):

	ftp://ftp.us.kernel.org/pub/linux/kernel/people/people/axboe/patches/2.4.13-pre4/block-highmem-all-17.bz2

It's a long time that I want to include the anti-bounce bits, but I am
still looking into the vm. The uglier part is that I suspect we'll also
need to make a 2G bounce option for some hardware combination. I hope
I'm wrong :).

Andrea