From: "Vladimir V. Saveliev" <vs@namesys.com>
To: "Lin Shen (lshen)" <lshen@cisco.com>
Cc: reiserfs-list@namesys.com
Subject: Re: Why reiser does a disk write on every sync() call?
Date: Tue, 27 Mar 2007 11:59:48 +0400 [thread overview]
Message-ID: <200703271159.49505.vs@namesys.com> (raw)
In-Reply-To: <08A9A3213527A6428774900A80DBD8D803BB7CC3@xmb-sjc-222.amer.cisco.com>
Hello
On Monday 26 March 2007 22:12, Lin Shen (lshen) wrote:
> I'm using iostat to measure disk reads/writes associated with various
> file operations under Reiser. One thing I noticed and can't explain is
> that every sync() call by itself (not following a write or anything)
> will cause an I/O write. Any ideas?
>
The I/O write is performed by reiserfs implementation of sync_fs method of struct super_operations.
If filesystem is mounted r/w - reiserfs_sync_fs begins a transaction (or joins an existing one), journal super block if the transaction has zero length,
closes the transaction and flushes old transactions including the one which was just closed. So, if there were no transaction to flush before sync() -
one transaction of length 1 gets created, closed, committed and flushed. 5 blocks get written to disk in this case. My calculation can be wrong, though.
How much I/O do you notice?
> Lin
>
>
next prev parent reply other threads:[~2007-03-27 7:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1174932216.16988.ezmlm@namesys.com>
2007-03-26 18:12 ` Why reiser does a disk write on every sync() call? Lin Shen (lshen)
2007-03-27 7:59 ` Vladimir V. Saveliev [this message]
2007-03-27 17:20 ` Lin Shen (lshen)
2007-03-27 18:54 ` Vladimir V. Saveliev
2007-05-12 13:03 ` Grzegorz Jaśkiewicz
2007-05-12 14:56 ` Toby Thain
2007-05-16 15:32 ` Vladimir V. Saveliev
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=200703271159.49505.vs@namesys.com \
--to=vs@namesys.com \
--cc=lshen@cisco.com \
--cc=reiserfs-list@namesys.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 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.