On Fri, Sep 25, 2020 at 12:41:29PM +0100, Tvrtko Ursulin wrote: > > On 25/09/2020 08:13, Leon Romanovsky wrote: > > On Thu, Sep 24, 2020 at 09:21:20AM +0100, Tvrtko Ursulin wrote: > > > > > > On 22/09/2020 09:39, Leon Romanovsky wrote: > > > > From: Maor Gottlieb <maorg@xxxxxxxxxxxx> > > > > > > > > Extend __sg_alloc_table_from_pages to support dynamic allocation of > > > > SG table from pages. It should be used by drivers that can't supply > > > > all the pages at one time. > > > > > > > > This function returns the last populated SGE in the table. Users should > > > > pass it as an argument to the function from the second call and forward. > > > > As before, nents will be equal to the number of populated SGEs (chunks). > > > > > > So it's appending and growing the "list", did I get that right? Sounds handy > > > indeed. Some comments/questions below. > > > > Yes, we (RDMA) use this function to chain contiguous pages. > > I will eveluate if i915 could start using it. We have some loops which build > page by page and coalesce. Christoph H doesn't like it, but if there are enough cases we should really have a pin_user_pages_to_sg() rather than open code this all over the place. With THP the chance of getting a coalescing SG is much higher, and everything is more efficient with larger SGEs. Jason
