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

Andrea Arcangeli
2004-12-25T20:04:46Z

On Sat, Dec 25, 2004 at 11:07:10AM -0800, William Lee Irwin III wrote:
> Lifting the artificial lowmem restrictions on blockdev mappings
> (thereby nuking mapping->gfp_mask altogether) would resolve a number of
> problems, not that anything making that much sense could ever happen.

I recall that such restriction is needed only for the buffercache, or
you'd need to change _all_ the fs to kmap before accessing metadata
(this is partly already happening for the dir in pagecache, but not for
everything else).

Whatever the problem is (assuming there's really a problem in the write
throttling) it isn't going away by eliminating that restriction. Just
think booting with mem=800M, it would run into the same issue that
happens right now with the artificial limitation and >=1G of ram.

2.4 has the same limitation and it has no problem with write throttling
(and from my part 2.6 is working fine too with the 4 patches I posted,
it's not me being able to reproduce it).