From mboxrd@z Thu Jan 1 00:00:00 1970 From: dexen deVries Subject: Cleancache Date: Wed, 8 Jun 2011 15:14:59 +0200 Message-ID: <201106081514.59693.dexen.devries@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:from:to:subject:date:user-agent:x-face :mime-version:content-type:content-transfer-encoding:message-id; bh=b9rZ/m1IvUvlIkXJ5Gz7goY5aX2grJZ4YX2GMVpoi9Y=; b=tIneAOUBxCJMo3fLu/IJDqYKc5SqiHaxNdg5ncSCyeStfVyny9GIRYLEyMZ3TxseNM OrZ9ftGVQZ+hjtjq/hhIdYR36UdFmhmNbdH67WpFVHzthPlhQgMTo7K6SHsfuyTtZt7g 5qP28XMtxY+J3h1I/TtPOpCTp4V27tBa562Xk= Sender: linux-nilfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: Text/Plain; charset="utf-8" To: linux-nilfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Hi list, there's that recent interesting addition to linux: `cleancache' (and=20 `zcache'). I've enabled it for NILFS2 yesterday (in 3.0-rc2). It seemed to work for a while -- sensible numbers in=20 /sys/kernel/mm/cleancache/*=20 But it broke terribly after performing echo 3 > /proc/sys/vm/drop_caches kernel reported NULL pointer dereference, IIRC. Ext4 works a-OK with th= at, so=20 my first guess waws NILFS2 is doing something funky with page allocatio= n or=20 mapping. Cleancache has own hooks into VFS, and for `normal' filesystem that's e= nough;=20 at least enough for ext3 and ext4 drivers to work reliably. On the othe= r hand,=20 btrfs does something unusual with pages and they used extra cleancache = hooks=20 for btrfs, IIRC. Should I dig further, post backtraces or something? I believe using cleancache + zcache could be beneficial, especially for= NILFS2=20 metadata like the DAT file; what are your thoughts on it? Regards, --=20 dexen deVries [[[=E2=86=93][=E2=86=92]]] =46or example, if the first thing in the file is: an XML parser will recognize that the document is stored in the traditi= onal=20 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