linux-kernel - [PATCH 0/3] [RFC][PATCH] clustered writeback

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 27 Aug 2007 19:21:52 +0800
From:	Fengguang Wu <wfg@...l.ustc.edu.cn>
To:	Chris Mason <chris.mason@...cle.com>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 0/3] [RFC][PATCH] clustered writeback

Chris,

This is one possible implementation of the clustered writeback idea.
It runs OK on ext3 (compiling, syncing, etc.).

The patch is based on 2.6.23-rc3-mm1 and the writeback patches here:
http://lkml.org/lkml/2007/8/19/10

By default, with many dirty inodes, it works as follows:
- store dirty inodes in a radix tree, indexed by their inode numbers
- sweep the whole inode number space in 25s and do it in 5 times
- each time we walk only 1/5 of the inode number space
- pull all inodes with dirty-age larger than 5s to the io dispatching queue

Because it does the work in small batches of 10 inodes, when the system has
<=10 dirty inodes, its behavior will reduce to:
- do a full sweep *at once* on every 25s
Which means the disk will flicker once every 25s, not bad :)


The implications for the majority users could be:
- medium-to-heavy writes becomes less seeky
- dirty inodes are getting synced earlier(before: 30s; now: 5-30s)
- less panic for the 'atime' mount option (a future work)

Fengguang
-- 
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/