From: Doug Ledford <dledford@redhat.com>
To: doug@easyco.com
Cc: Matt Garman <matthew.garman@gmail.com>,
Mdadm <linux-raid@vger.kernel.org>
Subject: Re: kernel checksumming performance vs actual raid device performance
Date: Tue, 23 Aug 2016 15:26:41 -0400 [thread overview]
Message-ID: <b12e01c4-72c1-1bc1-3662-3b616d510f85@redhat.com> (raw)
In-Reply-To: <CAFx4rwTwZPs5gzDXBc+fLVLCi6RW2=uWC1TaK7uNfJ48MxzHWQ@mail.gmail.com>
[-- Attachment #1.1: Type: text/plain, Size: 697 bytes --]
On 8/23/2016 3:19 PM, Doug Dumitru wrote:
> Mr. Ledford,
>
> I am glad that we are in agreement. My issue is that if the customer
> is reading 4GB/sec with a non-degraded array, the degraded array
> should only have 2X the number of IOs and 2X the transfer sizes to the
> drives. If the data rate falls to 1GB, I can suspect cpu overhead.
> With this case falling to 200MB/sec, then something else is going on.
>
> SSDs tend to be very "flat" reading from q=1 up to about q=20 assuming
> the HBAs can keep up.
Is he using SSDs? If so, I missed that bit. I wrote my response
assuming rotating media.
--
Doug Ledford <dledford@redhat.com>
GPG Key ID: 0E572FDD
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 884 bytes --]
next prev parent reply other threads:[~2016-08-23 19:26 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-12 21:09 kernel checksumming performance vs actual raid device performance Matt Garman
2016-07-13 3:58 ` Brad Campbell
[not found] ` <CAFx4rwQj3_JTNiS0zsQjp_sPXWkrp0ggjg_UiR7oJ8u0X9PQVA@mail.gmail.com>
2016-07-13 16:52 ` Fwd: " Doug Dumitru
2016-08-16 19:44 ` Matt Garman
2016-08-16 22:51 ` Doug Dumitru
2016-08-17 0:27 ` Adam Goryachev
[not found] ` <CAFx4rwTawqrBOWVwtPnGhRRAM1XiGQkS-o3YykmD0AftR45YkA@mail.gmail.com>
2016-08-23 14:34 ` Matt Garman
2016-08-23 15:02 ` Chris Murphy
[not found] ` <CAJvUf-Dqesy2TJX7W-bPakzeDcOoNy0VoSWWM06rKMYMhyhY7g@mail.gmail.com>
[not found] ` <CAFx4rwSQQuqeCFm+60+Gm75D49tg+mVjU=BnQSZThdE7E6KqPQ@mail.gmail.com>
2016-08-23 14:54 ` Matt Garman
2016-08-23 18:00 ` Doug Ledford
2016-08-23 18:27 ` Doug Dumitru
2016-08-23 19:10 ` Doug Ledford
2016-08-23 19:19 ` Doug Dumitru
2016-08-23 19:26 ` Doug Ledford [this message]
2016-08-23 19:26 ` Matt Garman
2016-08-23 19:41 ` Doug Dumitru
2016-08-23 20:15 ` Doug Ledford
2016-08-23 21:42 ` Phil Turmel
2016-08-24 1:02 ` Shaohua Li
2016-08-25 15:07 ` Matt Garman
2016-08-25 23:39 ` Adam Goryachev
2016-08-26 13:01 ` Matt Garman
2016-08-26 20:04 ` Doug Dumitru
2016-08-26 21:57 ` Phil Turmel
2016-08-26 22:11 ` Doug Dumitru
2016-08-26 18:11 ` Wols Lists
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=b12e01c4-72c1-1bc1-3662-3b616d510f85@redhat.com \
--to=dledford@redhat.com \
--cc=doug@easyco.com \
--cc=linux-raid@vger.kernel.org \
--cc=matthew.garman@gmail.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).