From: Tejun Heo <tj@kernel.org>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org, jack@suse.cz,
hch@infradead.org, hannes@cmpxchg.org,
linux-fsdevel@vger.kernel.org, lizefan@huawei.com,
cgroups@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.cz,
clm@fb.com, fengguang.wu@intel.com, david@fromorbit.com,
gthelen@google.com
Subject: Re: [PATCH 28/48] writeback: implement and use mapping_congested()
Date: Fri, 27 Mar 2015 17:46:13 -0400 [thread overview]
Message-ID: <20150327214613.GF638@htj.duckdns.org> (raw)
In-Reply-To: <20150327180626.GA19117@redhat.com>
Hello, Vivek.
On Fri, Mar 27, 2015 at 02:06:26PM -0400, Vivek Goyal wrote:
...
> > +int mapping_congested(struct address_space *mapping,
> > + struct task_struct *task, int cong_bits)
> > +{
> > + struct inode *inode = mapping->host;
> > + struct backing_dev_info *bdi = inode_to_bdi(inode);
> > + struct bdi_writeback *wb;
> > + int ret = 0;
> > +
> > + if (!inode || !inode_cgwb_enabled(inode))
> > + return wb_congested(&bdi->wb, cong_bits);
> > +
> > + rcu_read_lock();
> > + wb = wb_find_current(bdi);
>
> I am wondering that why do we lookup bdi_writeback using blkcg of
> task and why not use the bdi_writeback associated with inode?
>
> IIUC, whole idea is to attach an inode to bdi_writeback (and
> change it later if need be) and that writeback is used for
> controlling IO to that inode. And blkcg associated with the
> writeback will be put in bio which in turn will be used
> by block layer.
>
> IOW, blkcg of a bio gets decided by the bdi_writeback
> attached to inode and current writer does not seem to
> matter. So I am not sure why mapping_congested() should
> take task's blkcg into consideration instead of just
> taking bdi_writeback from inode and see if it is congested
> or not.
Yeap, I agree that attributing to the inode's blkcg makes more sense.
I need to think more about it but will prolly change it to use
inode->i_wb instead.
Thanks.
--
tejun
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next prev parent reply other threads:[~2015-03-27 21:46 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-23 4:54 [PATCHSET 1/3 v2 block/for-4.1/core] writeback: cgroup writeback support Tejun Heo
2015-03-23 4:54 ` [PATCH 01/48] memcg: add per cgroup dirty page accounting Tejun Heo
2015-03-23 4:54 ` [PATCH 02/48] blkcg: move block/blk-cgroup.h to include/linux/blk-cgroup.h Tejun Heo
2015-03-23 4:54 ` [PATCH 03/48] update !CONFIG_BLK_CGROUP dummies in include/linux/blk-cgroup.h Tejun Heo
2015-03-23 4:54 ` [PATCH 04/48] memcg: add mem_cgroup_root_css Tejun Heo
2015-03-23 4:54 ` [PATCH 05/48] blkcg: add blkcg_root_css Tejun Heo
2015-03-23 4:54 ` [PATCH 06/48] cgroup, block: implement task_get_css() and use it in bio_associate_current() Tejun Heo
2015-03-23 4:54 ` [PATCH 07/48] blkcg: implement task_get_blkcg_css() Tejun Heo
2015-03-23 4:54 ` [PATCH 08/48] blkcg: implement bio_associate_blkcg() Tejun Heo
2015-03-23 4:54 ` [PATCH 09/48] memcg: implement mem_cgroup_css_from_page() Tejun Heo
2015-03-23 4:54 ` [PATCH 10/48] writeback: move backing_dev_info->state into bdi_writeback Tejun Heo
2015-03-23 4:54 ` [PATCH 11/48] writeback: move backing_dev_info->bdi_stat[] " Tejun Heo
2015-03-23 4:54 ` [PATCH 12/48] writeback: move bandwidth related fields from backing_dev_info " Tejun Heo
2015-03-23 4:54 ` [PATCH 13/48] writeback: s/bdi/wb/ in mm/page-writeback.c Tejun Heo
2015-03-23 4:54 ` [PATCH 14/48] writeback: move backing_dev_info->wb_lock and ->worklist into bdi_writeback Tejun Heo
2015-03-23 4:54 ` [PATCH 15/48] writeback: reorganize mm/backing-dev.c Tejun Heo
2015-03-23 4:54 ` [PATCH 16/48] writeback: separate out include/linux/backing-dev-defs.h Tejun Heo
2015-03-23 4:54 ` [PATCH 17/48] bdi: make inode_to_bdi() inline Tejun Heo
2015-03-23 4:54 ` [PATCH 18/48] writeback: add @gfp to wb_init() Tejun Heo
2015-03-23 4:54 ` [PATCH 19/48] bdi: separate out congested state into a separate struct Tejun Heo
2015-03-23 4:54 ` [PATCH 20/48] writeback: add {CONFIG|BDI_CAP|FS}_CGROUP_WRITEBACK Tejun Heo
2015-03-23 4:54 ` [PATCH 21/48] writeback: make backing_dev_info host cgroup-specific bdi_writebacks Tejun Heo
2015-03-27 21:06 ` Vivek Goyal
2015-03-27 21:41 ` Tejun Heo
2015-03-23 4:54 ` [PATCH 22/48] writeback, blkcg: associate each blkcg_gq with the corresponding bdi_writeback_congested Tejun Heo
2015-03-23 4:54 ` [PATCH 23/48] writeback: attribute stats to the matching per-cgroup bdi_writeback Tejun Heo
2015-03-23 4:54 ` [PATCH 24/48] writeback: let balance_dirty_pages() work on the matching cgroup bdi_writeback Tejun Heo
2015-03-23 4:54 ` [PATCH 25/48] writeback: make congestion functions per bdi_writeback Tejun Heo
2015-03-23 4:54 ` [PATCH 26/48] writeback, blkcg: restructure blk_{set|clear}_queue_congested() Tejun Heo
2015-03-23 4:54 ` [PATCH 27/48] writeback, blkcg: propagate non-root blkcg congestion state Tejun Heo
2015-03-23 4:54 ` [PATCH 28/48] writeback: implement and use mapping_congested() Tejun Heo
2015-03-27 18:06 ` Vivek Goyal
2015-03-27 21:46 ` Tejun Heo [this message]
2015-03-23 4:54 ` [PATCH 29/48] writeback: implement WB_has_dirty_io wb_state flag Tejun Heo
2015-03-23 4:54 ` [PATCH 30/48] writeback: implement backing_dev_info->tot_write_bandwidth Tejun Heo
2015-03-23 4:54 ` [PATCH 31/48] writeback: make bdi_has_dirty_io() take multiple bdi_writeback's into account Tejun Heo
2015-03-23 4:54 ` [PATCH 32/48] writeback: don't issue wb_writeback_work if clean Tejun Heo
2015-03-23 4:54 ` [PATCH 33/48] writeback: make bdi->min/max_ratio handling cgroup writeback aware Tejun Heo
2015-03-23 4:54 ` [PATCH 34/48] writeback: implement bdi_for_each_wb() Tejun Heo
2015-03-23 4:54 ` [PATCH 35/48] writeback: remove bdi_start_writeback() Tejun Heo
2015-03-23 4:54 ` [PATCH 36/48] writeback: make laptop_mode_timer_fn() handle multiple bdi_writeback's Tejun Heo
2015-03-23 4:54 ` [PATCH 37/48] writeback: make writeback_in_progress() take bdi_writeback instead of backing_dev_info Tejun Heo
2015-03-23 4:54 ` [PATCH 38/48] writeback: make bdi_start_background_writeback() " Tejun Heo
2015-03-23 4:54 ` [PATCH 39/48] writeback: make wakeup_flusher_threads() handle multiple bdi_writeback's Tejun Heo
2015-03-23 4:54 ` [PATCH 40/48] writeback: add wb_writeback_work->auto_free Tejun Heo
2015-03-23 4:54 ` [PATCH 41/48] writeback: implement bdi_wait_for_completion() Tejun Heo
2015-03-23 4:54 ` [PATCH 42/48] writeback: implement wb_wait_for_single_work() Tejun Heo
2015-03-23 4:54 ` [PATCH 43/48] writeback: restructure try_writeback_inodes_sb[_nr]() Tejun Heo
2015-03-23 4:54 ` [PATCH 44/48] writeback: make writeback initiation functions handle multiple bdi_writeback's Tejun Heo
2015-03-23 4:54 ` [PATCH 45/48] writeback: dirty inodes against their matching cgroup bdi_writeback's Tejun Heo
2015-03-23 4:54 ` [PATCH 46/48] buffer, writeback: make __block_write_full_page() honor cgroup writeback Tejun Heo
2015-03-23 4:54 ` [PATCH 47/48] mpage: make __mpage_writepage() " Tejun Heo
2015-03-23 4:54 ` [PATCH 48/48] ext2: enable cgroup writeback support Tejun Heo
2015-03-25 15:40 ` [PATCHSET 1/3 v2 block/for-4.1/core] writeback: " Vivek Goyal
2015-03-25 16:01 ` Tejun Heo
2015-03-31 15:26 ` Tejun Heo
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