linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Ming Lei <tom.leiming@gmail.com>
To: Shaohua Li <shli@kernel.org>
Cc: Jens Axboe <axboe@fb.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"open list:SOFTWARE RAID (Multiple Disks) SUPPORT" 
	<linux-raid@vger.kernel.org>,
	linux-block <linux-block@vger.kernel.org>,
	Christoph Hellwig <hch@infradead.org>, NeilBrown <neilb@suse.com>
Subject: Re: [PATCH 00/17] md: cleanup on direct access to bvec table
Date: Fri, 17 Feb 2017 09:25:27 +0800	[thread overview]
Message-ID: <CACVXFVPRuikOn=zJ5fboGMyQs3rMxaUK4f-Lk0s-+HpPy+ov8w@mail.gmail.com> (raw)
In-Reply-To: <20170216221642.sobqndndd7fbjoo7@kernel.org>

Hi Shaohua,

On Fri, Feb 17, 2017 at 6:16 AM, Shaohua Li <shli@kernel.org> wrote:
> On Thu, Feb 16, 2017 at 07:45:30PM +0800, Ming Lei wrote:
>> In MD's resync I/O path, there are lots of direct access to bio's
>> bvec table. This patchset kills most of them, and the conversion
>> is quite straightforward.
>
> I don't like this approach. The MD uses a hacky way to manage pages allocated,
> this is the root of the problem. The patches add another hack way to do the

Yes, I agree, and bio_iov_iter_get_pages() uses this kind of hacky way too
actually.

> management. I'd like to see explict management of the pages, for example, add
> data structure in r1bio to manage the pages, then we can use existing API for
> all the stuffes we need.

Yeah, that is definitely clean, but we have to pay the following cost:

- allocate at least N * (128 + 4) bytes per each r1_bio/r10_bio
- N is pool_info.raid_disks for raid1, and conf->copies for raid10

If we are happy to introduce the cost, I can take this way in V1.


Thanks,
Ming Lei

  reply	other threads:[~2017-02-17  1:25 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-16 11:45 [PATCH 00/17] md: cleanup on direct access to bvec table Ming Lei
2017-02-16 11:45 ` [PATCH 01/17] block: introduce bio_segments_all() Ming Lei
2017-02-16 11:45 ` [PATCH 02/17] block: introduce bio_remove_last_page() Ming Lei
2017-02-16 12:08   ` Johannes Thumshirn
2017-02-16 13:30     ` Ming Lei
2017-02-16 13:40       ` Johannes Thumshirn
2017-02-16 13:59         ` Ming Lei
2017-02-16 14:10           ` Johannes Thumshirn
2017-02-16 11:45 ` [PATCH 03/17] md: raid1/raid10: use bio_remove_last_page() Ming Lei
2017-02-16 11:45 ` [PATCH 04/17] md: introduce helpers for dealing with fetch/store preallocated pages in bio Ming Lei
2017-02-16 11:45 ` [PATCH 05/17] md: raid1/raid10: use the introduced helpers Ming Lei
2017-02-16 11:45 ` [PATCH 06/17] md: raid1/raid10: borrow .bi_error as pre-allocated page index Ming Lei
2017-02-16 11:45 ` [PATCH 07/17] md: raid1/raid10: don't use .bi_vcnt to check if all pages are added Ming Lei
2017-02-16 11:45 ` [PATCH 08/17] md: raid1: simplify r1buf_pool_free() Ming Lei
2017-02-16 11:45 ` [PATCH 09/17] md: raid1/raid10: use bio helper in *_pool_free Ming Lei
2017-02-16 11:45 ` [PATCH 10/17] md: raid1: remove direct access to bvec table in fix_sync_read_error Ming Lei
2017-02-16 11:45 ` [PATCH 11/17] md: raid1: use bio helper in process_checks() Ming Lei
2017-02-16 11:45 ` [PATCH 12/17] md: raid1: avoid direct access to bvec table " Ming Lei
2017-02-17  8:33   ` kbuild test robot
2017-02-16 11:45 ` [PATCH 13/17] md: raid1: use bio_segments_all() Ming Lei
2017-02-16 12:35   ` Johannes Thumshirn
2017-02-16 13:32     ` Ming Lei
2017-02-16 13:34       ` Johannes Thumshirn
2017-02-16 13:38         ` Ming Lei
2017-02-16 11:45 ` [PATCH 14/17] md: raid10: avoid direct access to bvec table in sync_request_write() Ming Lei
2017-02-16 11:45 ` [PATCH 15/17] md: raid10: avoid direct access to bvec table in fix_recovery_read_error Ming Lei
2017-02-16 11:45 ` [PATCH 16/17] md: raid10: avoid direct access to bvec table in reshape_request Ming Lei
2017-02-16 11:45 ` [PATCH 17/17] md: raid10: avoid direct access to bvec table in handle_reshape_read_error Ming Lei
2017-02-16 22:16 ` [PATCH 00/17] md: cleanup on direct access to bvec table Shaohua Li
2017-02-17  1:25   ` Ming Lei [this message]
2017-02-17  4:16     ` Shaohua Li

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='CACVXFVPRuikOn=zJ5fboGMyQs3rMxaUK4f-Lk0s-+HpPy+ov8w@mail.gmail.com' \
    --to=tom.leiming@gmail.com \
    --cc=axboe@fb.com \
    --cc=hch@infradead.org \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-raid@vger.kernel.org \
    --cc=neilb@suse.com \
    --cc=shli@kernel.org \
    /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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).