Re: [PATCH][1/2] adjust dirty threshold for lowmem-only mappings

Andrea Arcangeli
2005-01-02T16:19:06Z

On Sun, Jan 02, 2005 at 04:11:47PM +0100, Jens Axboe wrote:
> It should be lifted for block devices, it doesn't make any sense.

It cannot be lifted without:

1) creating aliasing between buffercache and blkdev pagecache
2) changing all fs to kmap around all buffercache accesses

2 would create an huge change (sure not a good idea during 2.6, 2.7 if
something). 1 would break lilo and tunefs and other things writing to a
superblock while the fs is mounted.

I effectively wrote it like 2 but I had to learn the hard way it broke
lilo in some weird configuration and IIRC Linus and Al fixed it very
nicely with current design.

There's no highmem and in turn no limit on 64bit in the first place, so
both efforts are worthless in the long term.