On Thu, Oct 18, 2018 at 08:11:23AM -0700, Matthew Wilcox wrote:
> On Thu, Oct 18, 2018 at 04:42:07PM +0200, Christoph Hellwig wrote:
> > This all seems quite complicated.
> >
> > I think the interface we'd want is more one that has a little
> > cache of a single page in the queue, and a little bitmap which
> > sub-page size blocks of it are used.
> >
> > Something like (pseudo code minus locking):
> >
> > void *blk_alloc_sector_buffer(struct block_device *bdev, gfp_t gfp)
> > {
> > unsigned block_size = block_size(bdev);
> >
> > if (blocksize >= PAGE_SIZE)
> > return (void *)__get_free_pages(gfp, get_order(blocksize));
> >
> > if (bdev->fragment_cache_page) {
> > [ <find fragment in bdev->fragment_cache_page using
> > e.g. bitmap and return if found]
> > }
> >
> > bdev->fragment_cache_page = (void *)__get_free_page(gfp);
> > goto find_again;
> > }
>
> This looks a lot like page_frag_alloc() except I think page_frag_alloc()
> may be more efficient.
Oh, nice. Sounds like XFS should just use page_frag_alloc. I'll give
it a spin.
