From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ryusuke Konishi Subject: Re: Cleancache Date: Wed, 08 Jun 2011 23:02:31 +0900 (JST) Message-ID: <20110608.230231.65968027.ryusuke@osrg.net> References: <201106081514.59693.dexen.devries@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <201106081514.59693.dexen.devries-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-nilfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: Text/Plain; charset="iso-2022-jp" To: dexen.devries-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org Cc: linux-nilfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On Wed, 8 Jun 2011 15:14:59 +0200, dexen deVries wrote: > Hi list, > > > there's that recent interesting addition to linux: `cleancache' (and > `zcache'). > I've enabled it for NILFS2 yesterday (in 3.0-rc2). > It seemed to work for a while -- sensible numbers in > /sys/kernel/mm/cleancache/* > But it broke terribly after performing > echo 3 > /proc/sys/vm/drop_caches > kernel reported NULL pointer dereference, IIRC. Ext4 works a-OK with that, so > my first guess waws NILFS2 is doing something funky with page allocation or > mapping. > > Cleancache has own hooks into VFS, and for `normal' filesystem that's enough; > at least enough for ext3 and ext4 drivers to work reliably. On the other hand, > btrfs does something unusual with pages and they used extra cleancache hooks > for btrfs, IIRC. > > Should I dig further, post backtraces or something? Interesting. Can you get a log of the oops ? I may have time to look into the problem in this weekend. Regards, Ryusuke Konishi > I believe using cleancache + zcache could be beneficial, especially for NILFS2 > metadata like the DAT file; what are your thoughts on it? > > > Regards, > -- > dexen deVries > > [[[↓][→]]] > > For example, if the first thing in the file is: > > an XML parser will recognize that the document is stored in the traditional > ROT13 encoding. > > (( Joe English, http://www.flightlab.com/~joe/sgml/faq-not.txt )) > -- > To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html