From: Paolo Bonzini <pbonzini@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-devel@nongnu.org, stefanha@redhat.com
Subject: Re: [Qemu-devel] [PATCH v2 11/12] mirror: support more than one in-flight AIO operation
Date: Mon, 21 Jan 2013 13:55:31 +0100 [thread overview]
Message-ID: <50FD3AC3.20502@redhat.com> (raw)
In-Reply-To: <50FD361F.1050608@redhat.com>
Il 21/01/2013 13:35, Kevin Wolf ha scritto:
> I'm wondering if a whole bitmap is really appropriate when you have at
> most 16 parallel requests in flight. Other places in qemu (like
> copy-on-read or qcow2 cluster allocation) use lists of in-flight
> requests instead.
>
> I'm not requesting a change here, just wondering what the reasons are
> and whether this, or the other places, or none of both should be changed
> long term.
The reason is simply that the code is reasoning in bitmaps a lot
(cow_bitmap and of course the dirty bitmap), so it was a natural pick
and the memory usage is not important. It is simpler and more efficient
than a linear scan.
I have the required information already in the MirrorOp struct indeed,
but I didn't need those in a list.
Paolo
next prev parent reply other threads:[~2013-01-21 12:55 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-16 17:31 [Qemu-devel] [PATCH v2 00/12] Drive mirroring performance improvements Paolo Bonzini
2013-01-16 17:31 ` [Qemu-devel] [PATCH v2 01/12] host-utils: add ffsl Paolo Bonzini
2013-01-16 17:31 ` [Qemu-devel] [PATCH v2 02/12] add hierarchical bitmap data type and test cases Paolo Bonzini
2013-01-16 22:50 ` Eric Blake
2013-01-18 13:21 ` Kevin Wolf
2013-01-16 17:31 ` [Qemu-devel] [PATCH v2 03/12] block: implement dirty bitmap using HBitmap Paolo Bonzini
2013-01-16 17:31 ` [Qemu-devel] [PATCH v2 04/12] block: make round_to_clusters public Paolo Bonzini
2013-01-16 17:31 ` [Qemu-devel] [PATCH v2 05/12] mirror: perform COW if the cluster size is bigger than the granularity Paolo Bonzini
2013-01-18 15:13 ` Kevin Wolf
2013-01-18 16:22 ` Paolo Bonzini
2013-01-18 17:05 ` Kevin Wolf
2013-01-18 17:33 ` Paolo Bonzini
2013-01-21 10:17 ` Kevin Wolf
2013-01-21 11:15 ` Paolo Bonzini
2013-01-16 17:31 ` [Qemu-devel] [PATCH v2 06/12] block: return count of dirty sectors, not chunks Paolo Bonzini
2013-01-16 17:31 ` [Qemu-devel] [PATCH v2 07/12] block: allow customizing the granularity of the dirty bitmap Paolo Bonzini
2013-01-16 23:39 ` Eric Blake
2013-01-16 17:31 ` [Qemu-devel] [PATCH v2 08/12] mirror: allow customizing the granularity Paolo Bonzini
2013-01-16 23:44 ` Eric Blake
2013-01-21 11:00 ` Kevin Wolf
2013-01-16 17:31 ` [Qemu-devel] [PATCH v2 09/12] mirror: switch mirror_iteration to AIO Paolo Bonzini
2013-01-21 11:39 ` Kevin Wolf
2013-01-21 12:09 ` Paolo Bonzini
2013-01-21 12:15 ` Kevin Wolf
2013-01-16 17:31 ` [Qemu-devel] [PATCH v2 10/12] mirror: add buf-size argument to drive-mirror Paolo Bonzini
2013-01-16 23:46 ` Eric Blake
2013-01-16 17:31 ` [Qemu-devel] [PATCH v2 11/12] mirror: support more than one in-flight AIO operation Paolo Bonzini
2013-01-21 12:35 ` Kevin Wolf
2013-01-21 12:55 ` Paolo Bonzini [this message]
2013-01-16 17:31 ` [Qemu-devel] [PATCH v2 12/12] mirror: support arbitrarily-sized iterations Paolo Bonzini
2013-01-16 23:48 ` [Qemu-devel] [PATCH v2 00/12] Drive mirroring performance improvements Eric Blake
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=50FD3AC3.20502@redhat.com \
--to=pbonzini@redhat.com \
--cc=kwolf@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=stefanha@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 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).