On Tue, Jun 04, 2024 at 12:27:06AM +0300, Sagi Grimberg wrote: >>> I still don't understand how a page in the middle of a contiguous range ends >>> up coming from the slab while others don't. >> I haven't investigate the origin of the IO >> yet. I suspect the first 2 pages are the superblocks of the raid >> (mdp_superblock_1 and bitmap_super_s) and the rest of the IO is the bitmap. > > Well, if these indeed are different origins and just *happen* to be a > mixture > of slab originated pages and non-slab pages combined together in a single > bio of a bvec entry, > I'd suspect that it would be more beneficial to split the bvec (essentially > not allow bio_add_page > to append the page to tail bvec depending on a queue limit (similar to how > we handle sg gaps). So you want to add a PageSlab check to bvec_try_merge_page? That sounds fairly expensive..
