From: Milan Broz <gmazyland@gmail.com>
To: NeilBrown <neilb@suse.de>
Cc: Phil Turmel <philip@turmel.org>,
Christoph Anton Mitterer <calestyo@scientia.net>,
linux-raid@vger.kernel.org
Subject: Re: some general questions on RAID
Date: Mon, 08 Jul 2013 07:25:53 +0200 [thread overview]
Message-ID: <51DA4D61.2090708@gmail.com> (raw)
In-Reply-To: <20130708145316.4486d0dc@notabene.brown>
On 07/08/2013 06:53 AM, NeilBrown wrote:
> On Sun, 07 Jul 2013 19:39:27 +0200 Milan Broz <gmazyland@gmail.com> wrote:
>
>
>> So if you have multiple IOs submitted in parallel from *different* CPUs,
>> they are processed in parallel.
>>
>> If you have MD over dmcrypt, this can cause problem that MD sumbits all IOs
>> with the same cpu context and dmcrypt cannot run it in parallel.
>
> For RAID1 and RAID10 this isn't true any more.
>
> Commit f54a9d0e59c4bea3db733921ca9147612a6f292c
> in 3.6 changed this for RAID1 and a similar commit did for RAID10.
> RAID4/5/6 still submit from a single thread as you say.
Ah, sorry, missed that change, thanks Neil!
So then it should perform much better.
(But IIRC most reports about dmcrypt performance was either over
high-speed SSD without AES-NI or over RAID5 - case like huge ftp archive
where they need redundancy & offline data security.
But here current design should be help...)
Milan
next prev parent reply other threads:[~2013-07-08 5:25 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-04 18:30 some general questions on RAID Christoph Anton Mitterer
2013-07-04 22:07 ` Phil Turmel
2013-07-04 23:34 ` Christoph Anton Mitterer
2013-07-08 4:48 ` NeilBrown
2013-07-06 1:33 ` Christoph Anton Mitterer
2013-07-06 8:52 ` Stan Hoeppner
2013-07-06 15:15 ` Christoph Anton Mitterer
2013-07-07 16:51 ` Stan Hoeppner
2013-07-07 17:39 ` Milan Broz
2013-07-07 18:01 ` Christoph Anton Mitterer
2013-07-07 18:50 ` Milan Broz
2013-07-07 20:51 ` Christoph Anton Mitterer
2013-07-08 5:40 ` Milan Broz
2013-07-08 4:53 ` NeilBrown
2013-07-08 5:25 ` Milan Broz [this message]
2013-07-05 1:13 ` Brad Campbell
2013-07-05 1:39 ` Sam Bingner
2013-07-05 3:06 ` Brad Campbell
2013-07-06 1:23 ` some general questions on RAID (OT) Christoph Anton Mitterer
2013-07-06 6:23 ` Sam Bingner
2013-07-06 15:11 ` Christoph Anton Mitterer
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=51DA4D61.2090708@gmail.com \
--to=gmazyland@gmail.com \
--cc=calestyo@scientia.net \
--cc=linux-raid@vger.kernel.org \
--cc=neilb@suse.de \
--cc=philip@turmel.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 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.