linux-ext4 - Re: [PATCHSET v3.1 0/7] data integrity: Stabilize pages during writeback for various fses

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 for Android: free password hash cracker in your pocket

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

Date:	Tue, 10 May 2011 18:22:37 +0200
From:	Jan Kara <jack@...e.cz>
To:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Cc:	Jan Kara <jack@...e.cz>, "Darrick J. Wong" <djwong@...ibm.com>,
	Theodore Tso <tytso@....edu>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Jens Axboe <axboe@...nel.dk>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	Jeff Layton <jlayton@...hat.com>,
	Dave Chinner <david@...morbit.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Christoph Hellwig <hch@...radead.org>, linux-mm@...ck.org,
	Chris Mason <chris.mason@...cle.com>,
	Joel Becker <jlbec@...lplan.org>,
	linux-scsi <linux-scsi@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	linux-ext4@...r.kernel.org, Mingming Cao <mcao@...ibm.com>
Subject: Re: [PATCHSET v3.1 0/7] data integrity: Stabilize pages during
 writeback for various fses

On Wed 11-05-11 01:12:13, OGAWA Hirofumi wrote:
> Jan Kara <jack@...e.cz> writes:
> 
> >> Did you already consider, to copy only if page was writeback (like
> >> copy-on-write)? I.e. if page is on I/O, copy, then switch the page for
> >> writing new data.
> >   Yes, that was considered as well. We'd have to essentially migrate the
> > page that is under writeback and should be written to. You are going to pay
> > the cost of page allocation, copy, increased memory & cache pressure.
> > Depending on your backing storage and workload this may or may not be better
> > than waiting for IO...
> 
> Maybe possible, but you really think on usual case just blocking is
> better?
  Define usual case... As Christoph noted, we don't currently have a real
practical case where blocking would matter (since frequent rewrites are
rather rare). So defining what is usual when we don't have a single real
case is kind of tough ;)

								Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html