From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fengguang Wu Subject: [PATCH 0/6] buffered write IO controller in balance_dirty_pages() Date: Wed, 28 Mar 2012 20:13:08 +0800 Message-ID: <20120328121308.568545879@intel.com> Cc: Vivek Goyal To: Linux Memory Management List Return-path: cc: Suresh Jayaraman , Andrea Righi cc: Jeff Moyer cc: Cc: Fengguang Wu , LKML Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org Here is one possible solution to "buffered write IO controller", based on Linux v3.3 git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux.git buffered-write-io-controller Features: - support blkio.weight - support blkio.throttle.buffered_write_bps Possibilities: - it's trivial to support per-bdi .weight or .buffered_write_bps Pros: 1) simple 2) virtually no space/time overheads 3) independent of the block layer and IO schedulers, hence 3.1) supports all filesystems/storages, eg. NFS/pNFS, CIFS, sshfs, ... 3.2) supports all IO schedulers. One may use noop for SSDs, inside virtual machines, over iSCSI, etc. Cons: 1) don't try to smooth bursty IO submission in the flusher thread (*) 2) don't support IOPS based throttling 3) introduces semantic differences to blkio.weight, which will be - working by "bandwidth" for buffered writes - working by "device time" for direct IO (*) Maybe not a big concern, since the bursties are limited to 500ms: if one dd is throttled to 50% disk bandwidth, the flusher thread will be waking up on every 1 second, keep the disk busy for 500ms and then go idle for 500ms; if throttled to 10% disk bandwidth, the flusher thread will wake up on every 5s, keep busy for 500ms and stay idle for 4.5s. The test results included in the last patch look pretty good in despite of the simple implementation. [PATCH 1/6] blk-cgroup: move blk-cgroup.h in include/linux/blk-cgroup.h [PATCH 2/6] blk-cgroup: account dirtied pages [PATCH 3/6] blk-cgroup: buffered write IO controller - bandwidth weight [PATCH 4/6] blk-cgroup: buffered write IO controller - bandwidth limit [PATCH 5/6] blk-cgroup: buffered write IO controller - bandwidth limit interface [PATCH 6/6] blk-cgroup: buffered write IO controller - debug trace The changeset is dominated by the blk-cgroup.h move. The core changes (to page-writeback.c) are merely 77 lines. block/blk-cgroup.c | 27 + block/blk-cgroup.h | 364 -------------------------- block/blk-throttle.c | 2 block/cfq.h | 2 include/linux/blk-cgroup.h | 396 +++++++++++++++++++++++++++++ include/trace/events/writeback.h | 34 ++ mm/page-writeback.c | 77 +++++ 7 files changed, 530 insertions(+), 372 deletions(-) Thanks, Fengguang -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org