On 08/11/2017 04:46 AM, Christoph Hellwig wrote: > On Wed, Aug 09, 2017 at 08:06:24PM -0700, Dan Williams wrote: >> I like it, but do you think we should switch to sbvec[<constant>] to >> preclude pathological cases where nr_pages is large? > > Yes, please. > > Then I'd like to see that the on-stack bio even matters for > mpage_readpage / mpage_writepage. Compared to all the buffer head > overhead the bio allocation should not actually matter in practice. I'm skeptical for that path, too. I also wonder how far we could go with just doing a per-cpu bio recycling facility, to reduce the cost of having to allocate a bio. The on-stack bio parts are fine for simple use case, where simple means that the patch just special cases the allocation, and doesn't have to change much else. I had a patch for bio recycling and batched freeing a year or two ago, I'll see if I can find and resurrect it. -- Jens Axboe -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
