Messages in this thread | | | Date | Tue, 5 Apr 2016 18:40:31 -0800 | From | Kent Overstreet <> | Subject | Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs |
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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.overstreet@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/?
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 complicated I agree.
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