From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755531Ab2I0Gy3 (ORCPT ); Thu, 27 Sep 2012 02:54:29 -0400 Received: from mail-bk0-f46.google.com ([209.85.214.46]:33497 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754720Ab2I0GyY (ORCPT ); Thu, 27 Sep 2012 02:54:24 -0400 MIME-Version: 1.0 In-Reply-To: <20120927040357.GO15236@dastard> References: <1348404995-14372-1-git-send-email-zwu.kernel@gmail.com> <1348404995-14372-8-git-send-email-zwu.kernel@gmail.com> <20120927040357.GO15236@dastard> Date: Thu, 27 Sep 2012 14:54:22 +0800 Message-ID: Subject: Re: [RFC v2 07/10] vfs: fork one kthread to update data temperature From: Zhi Yong Wu To: Dave Chinner Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linuxram@linux.vnet.ibm.com, viro@zeniv.linux.org.uk, cmm@us.ibm.com, tytso@mit.edu, marco.stornelli@gmail.com, stroetmann@ontolinux.com, diegocg@gmail.com, chris@csamuel.org, Zhi Yong Wu Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 27, 2012 at 12:03 PM, Dave Chinner wrote: > On Sun, Sep 23, 2012 at 08:56:32PM +0800, zwu.kernel@gmail.com wrote: >> From: Zhi Yong Wu >> >> Fork and run one kernel kthread to calculate >> that temperature based on some metrics kept >> in custom frequency data structs, and store >> the info in the hash table. > > No new kthreads, please. Use a per-superblock workqueue and a struct > delayed_work to run periodic work on each superblock. If no new kthread is created, which kthread will work on these delayed_work tasks? > > That will also remove all the nasty, nasty > !hot_track_temperature_update_kthread checks from the code, too. > > Also, I'd separate the work that the workqueue does from the patch > that introduces the work queue. That way there is only one new thing > to comment on in the patch. Further, I'd separate the aging code > from the code that updates the temperature map into it's own patch > as well.. > > Finally, you're going to need a shrinker to control the amount of > memory that is used in tracking hot regions - if we are throwing > inodes out of memory due to memory pressure, we most definitely are > going to need to reduce the amount of memory the tracking code is > using, even if it means losing useful information (i.e. the shrinker > accelerates the aging process). Great, I agree with you. > > Given the above, and the other comments earlier in the series, > there's not a lot of point in me spending time commenting on ethe > code in detail here as it will change significantly as a result of > all the earlier comments.... OK, i will complete the code change based on all your earlier comments ASAP. > > Cheers, > > Dave. > -- > Dave Chinner > david@fromorbit.com > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Regards, Zhi Yong Wu