linux-ext4 - Re: ext4 writepages is making tiny bios?

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

Message-ID: <20090903164209.GA28384@infradead.org>
Date:	Thu, 3 Sep 2009 12:42:09 -0400
From:	Christoph Hellwig <hch@...radead.org>
To:	Dave Chinner <david@...morbit.com>
Cc:	Christoph Hellwig <hch@...radead.org>,
	Theodore Tso <tytso@....edu>,
	Chris Mason <chris.mason@...cle.com>,
	linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	xfs@....sgi.com
Subject: Re: ext4 writepages is making tiny bios?

On Thu, Sep 03, 2009 at 03:52:01PM +1000, Dave Chinner wrote:
> > XFS did the mistake of trusting the VM, while everyone more or less
> > overrode it.  Removing all those checks and writing out much larger
> > data fixes it with a relatively small patch:
> > 
> > 	http://verein.lst.de/~hch/xfs/xfs-writeback-scaling
> 
> Careful:
> 
> -	tloff = min(tlast, startpage->index + 64);
> +	tloff = min(tlast, startpage->index + 8192);
> 
> That will cause 64k page machines to try to write back 512MB at a
> time. This will re-introduce similar to the behaviour in sles9 where
> writeback would only terminate at the end of an extent (because the
> mapping end wasn't capped like above).

Pretty good point, any applies to all the different things we discussed
recently.  Ted, should be maybe introduce a max_writeback_mb instead of
the max_writeback_pages in the VM, too?

--
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