Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753441AbbD1GtX (ORCPT ); Tue, 28 Apr 2015 02:49:23 -0400 Received: from mail.kernel.org ([198.145.29.136]:39327 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751656AbbD1GtU (ORCPT ); Tue, 28 Apr 2015 02:49:20 -0400 From: Ming Lin To: linux-kernel@vger.kernel.org Cc: Christoph Hellwig , Jens Axboe , Kent Overstreet , Dongsu Park , Ming Lin Subject: [RFC PATCH v2 00/10] simplify block layer based on immutable biovecs Date: Mon, 27 Apr 2015 23:48:27 -0700 Message-Id: <1430203717-13307-1-git-send-email-mlin@kernel.org> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5993 Lines: 117 Dongsu sent v1 of this patchset. https://lkml.org/lkml/2014/12/22/128 This is the second attempt of simplifying block layer based on immutable biovecs. Immutable biovecs, implemented by Kent Overstreet, have been available in mainline since v3.14. Its original goal was actually making generic_make_request() accept arbitrarily sized bios, and pushing the splitting down to the drivers or wherever it's required. See also discussions in the past, [1] [2] [3]. This will bring not only performance improvements, but also a great amount of reduction in code complexity all over the block layer. Performance gain is possible due to the fact that bio_add_page() does not have to check unnecesary conditions such as queue limits or if biovecs are mergeable. Those will be delegated to the driver level. Kent already said that he actually benchmarked the impact of this with fio on a micron p320h, which showed definitely a positive impact. Moreover, this patchset also allows a lot of code to be deleted, mainly because of removal of merge_bvec_fn() callbacks. We have been aware that it has been always a delicate issue for stacking block drivers (e.g. md and bcache) to handle merging bio consistently. This simplication will help every individual block driver avoid having such an issue. Patches are against 4.1-rc1. These are also available in my git repo at: https://git.kernel.org/cgit/linux/kernel/git/mlin/linux.git/log/?h=block-generic-req This patchset is a prerequisite of other consecutive patchsets, e.g. multipage biovecs, rewriting plugging, or rewriting direct-IO, which are excluded this time. That means, this patchset should not bring any regression to end-users. I did some basic test. I'll run more tests to get some peformance numbers. Comments are welcome. Ming [1] https://lkml.org/lkml/2014/11/23/263 [2] https://lkml.org/lkml/2013/11/25/732 [3] https://lkml.org/lkml/2014/2/26/618 Dongsu Park (1): Documentation: update notes in biovecs about arbitrarily sized bios Kent Overstreet (9): block: make generic_make_request handle arbitrarily sized bios block: simplify bio_add_page() block: allow __blk_queue_bounce() to handle bios larger than BIO_MAX_PAGES bcache: clean up hacks around bio_split_pool btrfs: remove bio splitting and merge_bvec_fn() calls md/raid5: get rid of bio_fits_rdev() block: kill merge_bvec_fn() completely fs: use helper bio_add_page() instead of open coding on bi_io_vec md/raid10: make sync_request_write() call bio_copy_data() Documentation/block/biovecs.txt | 10 +- block/bio.c | 135 +++++++++++---------------- block/blk-core.c | 19 ++-- block/blk-merge.c | 140 ++++++++++++++++++++++++++-- block/blk-mq.c | 2 + block/blk-settings.c | 22 ----- block/bounce.c | 60 ++++++++++-- drivers/block/drbd/drbd_int.h | 1 - drivers/block/drbd/drbd_main.c | 1 - drivers/block/drbd/drbd_req.c | 37 +------- drivers/block/pktcdvd.c | 27 +----- drivers/block/ps3vram.c | 2 + drivers/block/rbd.c | 47 ---------- drivers/block/rsxx/dev.c | 2 + drivers/block/umem.c | 2 + drivers/block/zram/zram_drv.c | 2 + drivers/md/bcache/bcache.h | 18 ---- drivers/md/bcache/io.c | 100 +------------------- drivers/md/bcache/journal.c | 4 +- drivers/md/bcache/request.c | 16 ++-- drivers/md/bcache/super.c | 32 +------ drivers/md/bcache/util.h | 5 +- drivers/md/bcache/writeback.c | 4 +- drivers/md/dm-cache-target.c | 21 ----- drivers/md/dm-crypt.c | 16 ---- drivers/md/dm-era-target.c | 15 --- drivers/md/dm-flakey.c | 16 ---- drivers/md/dm-linear.c | 16 ---- drivers/md/dm-log-writes.c | 16 ---- drivers/md/dm-snap.c | 15 --- drivers/md/dm-stripe.c | 21 ----- drivers/md/dm-table.c | 8 -- drivers/md/dm-thin.c | 31 ------ drivers/md/dm-verity.c | 16 ---- drivers/md/dm.c | 122 +----------------------- drivers/md/dm.h | 2 - drivers/md/linear.c | 43 --------- drivers/md/md.c | 28 +----- drivers/md/md.h | 12 --- drivers/md/multipath.c | 21 ----- drivers/md/raid0.c | 56 ----------- drivers/md/raid0.h | 2 - drivers/md/raid1.c | 58 +----------- drivers/md/raid10.c | 139 ++------------------------- drivers/md/raid5.c | 55 +---------- drivers/s390/block/dcssblk.c | 2 + drivers/s390/block/xpram.c | 2 + drivers/staging/lustre/lustre/llite/lloop.c | 2 + fs/btrfs/volumes.c | 72 -------------- fs/buffer.c | 7 +- fs/jfs/jfs_logmgr.c | 14 +-- include/linux/blkdev.h | 13 +-- include/linux/device-mapper.h | 4 - mm/page_io.c | 8 +- 54 files changed, 322 insertions(+), 1219 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/