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From: Vivek Goyal <vgoyal@redhat.com>
To: Tao Ma <tm@tao.ma>
Cc: Shaohua Li <shli@kernel.org>, Tejun Heo <tj@kernel.org>,
	axboe@kernel.dk, ctalbott@google.com, rni@google.com,
	linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
	containers@lists.linux-foundation.org
Subject: Re: IOPS based scheduler (Was: Re: [PATCH 18/21] blkcg: move blkio_group_conf->weight to cfq)
Date: Wed, 4 Apr 2012 14:22:38 -0400	[thread overview]
Message-ID: <20120404182238.GI12676@redhat.com> (raw)
In-Reply-To: <4F7C824D.2050308@tao.ma>

On Thu, Apr 05, 2012 at 01:18:05AM +0800, Tao Ma wrote:

[..]
> > I think a large chunk of that iops scheduler code will be borrowed from
> > CFQ code. All the cgroup logic, queue creation logic, group scheduling
> > logic etc. And that's the reason I was still exploring the possibility 
> > of having common code base.
> Yeah, actually I was thinking of abstracting a generic logic, but it
> seems a lot bit hard. Maybe we can try to unify the code later?

I think if we change the cfqq scheduling logic to something similar to
group scheduling logic, it will help a lot.

- Current virtual time based logic does not care whether you are operating
  in time mode or iops mode. Switching cfqq logic to similar logic will
  help moving to iops mode quickly.

- Keeping track of vtime will help that we will get rid of all the
  residual time logic. If some queue was preempted, and did not use full
  slice, we will automaticlally charge it less and give smaller vtime.

- Keeping both the scheduling logic will enable us the smoother
  integration of both cfqq and group logic once we support hierarchical
  cgroups.

- It will also enable easier integration of iops related logic.

So I am in favor of cleaning up CFQ code and change it to deal with both
time as well iops. Seriously, implmenting time or iops is not hard. It is
about rest of the logic like trees, groups which contributes towards bulk
of the code and I am really not convinced that iops scheduler is going to
be different enough that it needs new io scheduler.

Thanks
Vivek

  parent reply	other threads:[~2012-04-04 18:22 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-03-28 22:51 [PATCHSET] block: modularize blkcg config and stat file handling Tejun Heo
2012-03-28 22:51 ` [PATCH 01/21] blkcg: remove unused @pol and @plid parameters Tejun Heo
2012-03-28 22:51 ` [PATCH 02/21] blkcg: BLKIO_STAT_CPU_SECTORS doesn't have subcounters Tejun Heo
2012-03-28 22:51 ` [PATCH 03/21] blkcg: introduce blkg_stat and blkg_rwstat Tejun Heo
2012-03-28 22:51 ` [PATCH 04/21] blkcg: restructure statistics printing Tejun Heo
2012-03-28 22:51 ` [PATCH 05/21] blkcg: drop blkiocg_file_write_u64() Tejun Heo
2012-03-28 22:51 ` [PATCH 06/21] blkcg: restructure configuration printing Tejun Heo
2012-03-28 22:51 ` [PATCH 07/21] blkcg: restructure blkio_group configruation setting Tejun Heo
2012-03-28 22:51 ` [PATCH 08/21] blkcg: blkg_conf_prep() Tejun Heo
2012-03-28 22:53   ` Tejun Heo
2012-03-28 22:51 ` [PATCH 09/21] blkcg: export conf/stat helpers to prepare for reorganization Tejun Heo
2012-03-28 22:51 ` [PATCH 10/21] blkcg: implement blkio_policy_type->cftypes Tejun Heo
2012-03-28 22:51 ` [PATCH 11/21] blkcg: move conf/stat file handling code to policies Tejun Heo
2012-03-28 22:51 ` [PATCH 12/21] cfq: collapse cfq.h into cfq-iosched.c Tejun Heo
2012-03-28 22:51 ` [PATCH 13/21] blkcg: move statistics update code to policies Tejun Heo
2012-03-28 22:51 ` [PATCH 14/21] blkcg: cfq doesn't need per-cpu dispatch stats Tejun Heo
2012-03-28 22:51 ` [PATCH 15/21] blkcg: add blkio_policy_ops operations for exit and stat reset Tejun Heo
2012-03-28 22:51 ` [PATCH 16/21] blkcg: move blkio_group_stats to cfq-iosched.c Tejun Heo
2012-03-28 22:51 ` [PATCH 17/21] blkcg: move blkio_group_stats_cpu and friends to blk-throttle.c Tejun Heo
2012-03-28 22:51 ` [PATCH 18/21] blkcg: move blkio_group_conf->weight to cfq Tejun Heo
2012-04-01 21:09   ` Vivek Goyal
2012-04-01 21:22     ` Tejun Heo
2012-04-02 21:39   ` Tao Ma
2012-04-02 21:49     ` Tejun Heo
2012-04-02 22:03       ` Tao Ma
2012-04-02 22:17         ` Tejun Heo
2012-04-02 22:20           ` Tao Ma
2012-04-02 22:25             ` Vivek Goyal
2012-04-02 22:28               ` Tejun Heo
2012-04-02 22:41               ` Tao Ma
2012-04-03 15:37                 ` IOPS based scheduler (Was: Re: [PATCH 18/21] blkcg: move blkio_group_conf->weight to cfq) Vivek Goyal
2012-04-03 16:36                   ` Tao Ma
2012-04-03 16:50                     ` Vivek Goyal
2012-04-03 17:26                       ` Tao Ma
2012-04-04 12:35                         ` Shaohua Li
2012-04-04 13:37                           ` Vivek Goyal
2012-04-04 14:52                             ` Shaohua Li
2012-04-04 15:10                               ` Vivek Goyal
2012-04-04 16:06                                 ` Tao Ma
2012-04-04 16:45                             ` Tao Ma
2012-04-04 16:50                               ` Vivek Goyal
2012-04-04 17:17                                 ` Vivek Goyal
2012-04-04 17:18                                 ` Tao Ma
2012-04-04 17:27                                   ` Vivek Goyal
2012-04-04 18:22                                   ` Vivek Goyal [this message]
2012-04-04 18:36                                     ` Tao Ma
2012-04-04 13:31                         ` Vivek Goyal
2012-03-28 22:51 ` [PATCH 19/21] blkcg: move blkio_group_conf->iops and ->bps to blk-throttle Tejun Heo
2012-03-28 22:51 ` [PATCH 20/21] blkcg: pass around pd->pdata instead of pd itself in prfill functions Tejun Heo
2012-03-28 22:51 ` [PATCH 21/21] blkcg: drop BLKCG_STAT_{PRIV|POL|OFF} macros Tejun Heo
2012-03-29  8:18 ` [PATCHSET] block: modularize blkcg config and stat file handling Jens Axboe
2012-04-02 20:02   ` Tejun Heo
2012-04-02 21:51     ` Jens Axboe
2012-04-02 22:33       ` Tejun Heo
2012-04-01 19:38 ` Vivek Goyal
2012-04-01 21:42 ` Tejun Heo

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