From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f46.google.com ([209.85.220.46]:48823 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753256Ab2JRCO2 (ORCPT ); Wed, 17 Oct 2012 22:14:28 -0400 Date: Thu, 18 Oct 2012 10:25:30 +0800 From: Zheng Liu To: Zhi Yong Wu Cc: Dave Chinner , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linuxram@linux.vnet.ibm.com, viro@zeniv.linux.org.uk, dave@jikos.cz, tytso@mit.edu, cmm@us.ibm.com, Zhi Yong Wu Subject: Re: [RFC v3 09/13] vfs: add one wq to update map info periodically Message-ID: <20121018022530.GB24939@gmail.com> References: <1349863655-29320-1-git-send-email-zwu.kernel@gmail.com> <1349863655-29320-10-git-send-email-zwu.kernel@gmail.com> <20121016002744.GC2864@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Wed, Oct 17, 2012 at 02:34:15PM +0800, Zhi Yong Wu wrote: > >> diff --git a/fs/hot_tracking.h b/fs/hot_tracking.h > >> index d19e64a..7a79a6d 100644 > >> --- a/fs/hot_tracking.h > >> +++ b/fs/hot_tracking.h > >> @@ -36,6 +36,9 @@ > >> */ > >> #define TIME_TO_KICK 400 > >> > >> +/* set how often to update temperatures (seconds) */ > >> +#define HEAT_UPDATE_DELAY 400 > > > > FWIW, 400 seconds is an unusual time period. It's expected that > > periodic work might take place at intervals of 5 minutes, 10 > > minutes, etc, not 6m40s. It's much easier to predict and understand > > behaviour if it's at a interval of whole units like minutes, > > especially when looking at timestamped event traces. Hence 300s (5 > > minutes) makes a lot more sense as a period for updates... > got it. thanks. Hi Zhi Yong, IMHO we'd better to make this value parameterized, and then the user can adjust this value dynamically. Regards, Zheng