Re: Failing XFS memory allocation

Dave Chinner
2016-03-24T21:59:02Z

On Thu, Mar 24, 2016 at 11:20:23AM +0200, Nikolay Borisov wrote:
> On 03/24/2016 01:00 AM, Dave Chinner wrote:
> > As it is, yes, the memory allocation problem is with the in-core
> > extent tree, and we've known about it for some time. The issue is
> > that as memory gets fragmented, the top level indirection array
> > grows too large to be allocated as a contiguous chunk. When this
> > happens really depends on memory load, uptime and the way the extent
> > tree is being modified.
>
> And what about the following completely crazy idea of switching order >
> 3 allocations to using vmalloc? I know this would incur heavy
> performance hit, but other than that would it cause correctness issues?
> Of course I'm not saying this should be implemented in upstream rather
> whether it's worth it having a go for experimenting with this idea.

It's not an option as many supported platforms which have extremely
limited vmalloc space.

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com