Re: highmem question

[Jens Axboe]

On Fri, Dec 07 2001, Marvin Justice wrote:
> > There is no way of fixing it.
> 
> All I know is that a streaming io app I was playing with showed a drastic 
> performance hit when the kernel was compiled with CONFIG_HIGHMEM. On W2K we 
> saw no slowdown with 2 or even 4GB of RAM so I think solutions must exist.

That's because of highmem page bouncing when doing I/O. There is indeed
a solution for this -- 2.5 or 2.4 + block-highmem-all patches will
happily do I/O directly to any page in your system as long as your
hardware supports it. I'm sure we're beating w2k with that enabled :-)

-- 
Jens Axboe