On Fri, May 05, 2017 at 04:24:47PM +0200, David Sterba wrote: > On Mon, Apr 17, 2017 at 06:16:21PM -0700, Liu Bo wrote: > > This attempts to use bio_clone_fast() in the places where we clone bio, > > such as when bio got cloned for multiple disks and when bio got split > > during dio submit. > > > > One benefit is to simplify dio submit to avoid calling bio_add_page one by > > one. > > > > Another benefit is that comparing to bio_clone_bioset, bio_clone_fast is > > faster because of copying the vector pointer directly, and bio_clone_fast > > doesn't modify bi_vcnt, so the extra work is to fix up bi_vcnt usage we > > currently have to use bi_iter to iterate bvec. > > > > Liu Bo (6): > > Btrfs: use bio_clone_fast to clone our bio > > Please extend the changelog of this patch, use the text in the cover > letter. >
OK. > > Btrfs: use bio_clone_bioset_partial to simplify DIO submit > > This patch is too big, can you split it to smaller chunks? I was not > able to review it, it seems to touch several things at once, it's hard > to keep the context. > Oh I see, the diff does look scary but the changes are in fact not intrusive, I'll try to do something. > > Btrfs: change how we iterate bios in endio > > Btrfs: record error if one block has failed to retry > > Btrfs: change check-integrity to use bvec_iter > > Btrfs: unify naming of btrfs_io_bio > > The rest looks ok. > > Have you done perofrmance tests? Not that it's necessary, but would be > interesting to see the effects. The effects of simplified code are > likely unmeasurable, but the _fast version skips some mempool exercises > so this could lead to improvements under memory pressure. And these is > hardly deterministic conditions, could be hard. I'me expecting some > latency improvemtnest. I haven't done the perf. test since it is a RFC that I basically hope to check whether the idea makes sense. And yes, using bio_clone_fas could save us some memory which is allocated for bio->bi_io_vec if (nr_iovecs > inline_vecs). I'll do some tests to see if there is any perf. difference and drop a notice to intel's test robot if they can do much broader perf. tests against it. Thank you for the comments. Thanks, -liubo -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
