On Fri, Oct 03 2014 at 9:23am -0400, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > On Fri, Oct 03 2014 at 7:48am -0400, > Junichi Nomura <j-nomura@xxxxxxxxxxxxx> wrote: > > > This series of patches reduce the memory overhead of device-mapper > > device mainly by removing unused mempool for bio vecs. > > > > DM creates per-device bioset to ensure forward progress under > > low memory situation and bioset always includes mempool for bvec. > > > > However, with the introduction of immutable bvec by Kent Overstreet, > > dm core now uses bio_clone_fast for creating a clone bio, and no longer > > needs bvecs for it. > > > > For example, when you create 10,000 bio-based DM devices and 1,000 > > request-based DM devices, memory usage of biovec under no load is: > > # grep biovec /proc/slabinfo > > biovec-256 418068 418068 4096 ... > > biovec-128 0 0 2048 ... > > biovec-64 0 0 1024 ... > > biovec-16 0 0 256 ... > > > > With this patch series applied, the usage becomes: > > # grep biovec /proc/slabinfo > > biovec-256 116 116 4096 ... > > biovec-128 0 0 2048 ... > > biovec-64 0 0 1024 ... > > biovec-16 0 0 256 ... > > > > So 4096 * (418068 - 116) = 1.6GB of memory is saved in this example. > > Very nice Junichi! > > Kent definitely left us some low hanging fruit that offers a huge win > (and fixes the really long-standing problem of excessive memory reserves > for each request-based DM device!) > > Jens, this is obviously an awkward patchset given it touches both block > and DM (block more so than DM). I'd be fine with you pulling it into > block (or vice-versa if you're OK with me staging it for 3.18 via > linux-dm.git with your Acked-by). I picked up this patchset, refactored the patches based on my earlier suggested s/bioset_nobvec_create/bioset_create_nobvec/ rename and tweaked headers a bit. I've staged the result in the for-next branch of linux-dm.git for v3.18 inclusion, see: https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/log/?h=for-next b83bb63 dm: remove nr_iovecs parameter from alloc_tio() b875215 block: use bio_clone_fast() in blk_rq_prep_clone() cd595c9 block: add bioset_create_nobvec() 3611594 dm: use bioset_create_nobvec() Jens, I can easily yield this patchset to you if you care. Or I can backfill your Acked-by in the above 2 block commits (I obviously won't just send block changes upstream without your OK!). Please advise, thanks! Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
