From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Erik Slagter <erik@slagter.name>
Cc: linux-kernel@vger.kernel.org
Subject: Re: md mirror / ext3 / dual core performance strange phenomenon?
Date: Mon, 14 Aug 2006 15:01:54 +0100 [thread overview]
Message-ID: <1155564114.24077.212.camel@localhost.localdomain> (raw)
In-Reply-To: <1155561134.7809.27.camel@skylla.slagter.name>
Ar Llu, 2006-08-14 am 15:12 +0200, ysgrifennodd Erik Slagter:
> I am really blown away here. It looks like disk access is the bottleneck
> here, but I can't imagine my disks being so slow (at seeking, I guess)
> it should matter that much.
Keith has answered the main question but your assumptions about seeking
are also not neccessarily correct. Disk seek times as opposed to data
rates and density have not materially improved for many years now, nor
for IDE has the rotation speed and thus rotational latency to access
data.
RAID-1 mirroring generally helps performance as it speeds up the rate of
read command completion at the cost of slower writes. Writes are usually
buffered so tend not to impact performance unless you have a lot of I/O.
Alan
next prev parent reply other threads:[~2006-08-14 13:41 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-14 13:12 Erik Slagter
2006-08-14 13:22 ` Keith Owens
2006-08-14 13:26 ` Erik Slagter
2006-08-14 14:48 ` Alistair John Strachan
2006-08-14 14:01 ` Alan Cox [this message]
2006-08-14 13:49 ` Erik Slagter
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=1155564114.24077.212.camel@localhost.localdomain \
--to=alan@lxorguk.ukuu.org.uk \
--cc=erik@slagter.name \
--cc=linux-kernel@vger.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
all inboxes | Powered by JetHome®