From: Tejun Heo <tj@kernel.org>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: axboe@kernel.dk, ctalbott@google.com, rni@google.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 06/13] block, cfq: misc updates to cfq_io_context
Date: Thu, 27 Oct 2011 09:24:54 -0700 [thread overview]
Message-ID: <20111027162454.GC29899@google.com> (raw)
In-Reply-To: <20111027153901.GG7491@redhat.com>
Hello, Vivek.
On Thu, Oct 27, 2011 at 11:39:01AM -0400, Vivek Goyal wrote:
> On Tue, Oct 25, 2011 at 06:48:32PM -0700, Tejun Heo wrote:
> > Make the following changes to prepare for ioc/cic management cleanup.
> >
> > * Add cic->q so that ioc can determine the associated queue without
> > querying cfq. This will eventually replace ->key.
>
> Not sure what's the advantage of storing cic->q instead of cic->cfqd.
> In blk-ioc code getting to cic's queue becomes easier but then reaching
> to cfqd in cfq code becomes much longer.
It's primarily for API separation. Currently, io_context and cfq are
intermixed without clear layer of separation. The optimization of
avoiding one indirect deref at this level isn't worth blurring API
boundaries especially when the cachelines being derefed are known to
be hot (we're deep in elevator path after all). I'm working on a
patchset to make proper separation between them. If reducing that one
indrect load proves to be worthwhile (I'm extremely skeptical tho), we
can use another another caching entry in cic.
Thanks.
--
tejun
next prev parent reply other threads:[~2011-10-27 16:25 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-26 1:48 [PATCHSET block:for-3.2/core] rescue cfq from RCU death sprial :) Tejun Heo
2011-10-26 1:48 ` [PATCH 01/13] ida: make ida_simple_get/put() IRQ safe Tejun Heo
2011-10-26 4:42 ` Rusty Russell
2011-10-26 20:28 ` Tejun Heo
2011-10-26 1:48 ` [PATCH 02/13] block, cfq: move cfqd->cic_index to q->id Tejun Heo
2011-10-26 1:48 ` [PATCH 03/13] block: misc ioc cleanups Tejun Heo
2011-10-26 1:48 ` [PATCH 04/13] block: make ioc get/put interface more conventional and fix race on alloction Tejun Heo
2011-10-26 16:01 ` Vivek Goyal
2011-10-26 19:29 ` Tejun Heo
2011-10-26 21:30 ` [PATCH UPDATED " Tejun Heo
2011-10-26 1:48 ` [PATCH 05/13] block: misc updates to blk_get_queue() Tejun Heo
2011-10-26 1:48 ` [PATCH 06/13] block, cfq: misc updates to cfq_io_context Tejun Heo
2011-10-27 15:39 ` Vivek Goyal
2011-10-27 16:24 ` Tejun Heo [this message]
2011-10-26 1:48 ` [PATCH 07/13] block, cfq: move ioc ioprio/cgroup changed handling to cic Tejun Heo
2011-10-26 1:48 ` [PATCH 08/13] block, cfq: fix race condition in cic creation path and tighten locking Tejun Heo
2011-10-26 1:48 ` [PATCH 09/13] block, cfq: fix cic lookup locking Tejun Heo
2011-10-26 1:48 ` [PATCH 10/13] block, cfq: unlink cfq_io_context's immediately Tejun Heo
2011-10-26 19:48 ` Vivek Goyal
2011-10-26 19:55 ` Tejun Heo
2011-10-26 20:38 ` Vivek Goyal
2011-10-26 20:54 ` Tejun Heo
2011-10-26 21:31 ` [PATCH UPDATED " Tejun Heo
2011-10-27 14:31 ` Vivek Goyal
2011-10-27 16:17 ` Tejun Heo
2011-10-27 17:05 ` Vivek Goyal
2011-10-27 17:11 ` Tejun Heo
2011-10-26 1:48 ` [PATCH 11/13] block, cfq: remove delayed unlink Tejun Heo
2011-10-26 1:48 ` [PATCH 12/13] block, cfq: kill ioc_gone Tejun Heo
2011-10-26 1:48 ` [PATCH 13/13] block, cfq: kill cic->key Tejun Heo
2011-10-26 21:36 ` [PATCHSET block:for-3.2/core] rescue cfq from RCU death sprial :) Tejun Heo
2011-10-27 15:32 ` Vivek Goyal
2011-10-27 16:10 ` Tejun Heo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20111027162454.GC29899@google.com \
--to=tj@kernel.org \
--cc=axboe@kernel.dk \
--cc=ctalbott@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=rni@google.com \
--cc=vgoyal@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.