From: Magicloud Magiclouds <magicloud.magiclouds@gmail.com>
To: linux-btrfs@vger.kernel.org
Subject: Interesting problem with write data.
Date: Thu, 18 Nov 2010 14:19:40 +0800 [thread overview]
Message-ID: <AANLkTinTtvN6T6Ykjs6-UzHi3XYgimM92Pa5wSPrF3sZ@mail.gmail.com> (raw)
Hi,
Recently, I made a btrfs to use. And I met slowness problem. Trying
to diag it. I found this:
1. dd if=/dev/zero of=test count=1024 bs=1MB
This is fast, at about 25MB/s, and reasonable iowait.
2. dd if=/dev/zero of=test count=1 bs=1GB
This is pretty slow, at about 1.5MB/s, and 90%+ iowait, constantly.
May I know why it works like this? Thanks.
next reply other threads:[~2010-11-18 6:19 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-18 6:19 Magicloud Magiclouds [this message]
2010-11-18 10:36 ` Interesting problem with write data Wout Mertens
-- strict thread matches above, loose matches on Subject: below --
2010-11-18 12:03 Tomasz Chmielewski
2010-11-18 14:23 ` Chris Mason
2010-11-18 14:57 ` Tomasz Chmielewski
2010-11-18 15:07 ` Chris Mason
2010-11-18 15:39 ` Tomasz Chmielewski
2010-11-18 15:54 ` Chris Mason
2010-11-18 16:00 ` Tomasz Chmielewski
2010-11-18 16:07 ` Chris Mason
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=AANLkTinTtvN6T6Ykjs6-UzHi3XYgimM92Pa5wSPrF3sZ@mail.gmail.com \
--to=magicloud.magiclouds@gmail.com \
--cc=linux-btrfs@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;
as well as URLs for NNTP newsgroup(s).