On Wed, Apr 6, 2016 at 10:40 AM, Kent Overstreet <kent.overstr...@gmail.com> wrote: > On Wed, Apr 06, 2016 at 10:37:05AM +0800, Ming Lei wrote: >> On Wed, Apr 6, 2016 at 10:34 AM, Kent Overstreet >> <kent.overstr...@gmail.com> wrote: >> > On Wed, Apr 06, 2016 at 10:30:22AM +0800, Ming Lei wrote: >> >> Now limit.max_segments is for limiting segments from hw view, one this >> >> segment may include lots of pages/bvecs. >> >> >> >> The current bio_clone() issue is that we can't clone from one bio which >> >> includes more than 256 bvecs, maybe all these 256 bvecs belong to >> >> one same hw segment. >> > >> > So the distinction is purely a post multipage bvec thing? >> >> Even after multipage bvec is applied, the limit for max bvecs is still needed >> for some cases like bio bounce, in which bio_clone() need to >> clone single page bvec. > > s/max bvecs/max pages/?
Exactly, :-) > > What I meant is that until we have multipage bvecs, unless I'm missing > something > max_segments is exactly what we want. After multipage bvecs, things do get > more Yes, but now we need to fix current issue and backport the fix. Given bio bounce isn't easy to fix, not like other users of bio_clone, I think we still need to apply the max pages limit globally, what do you think of it? For multipage bvecs, there may be a long way ahead, :-) thanks, Ming > -- > To unsubscribe from this list: send the line "unsubscribe linux-block" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
