From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id BF8317F51 for ; Mon, 19 May 2014 16:57:17 -0500 (CDT) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay2.corp.sgi.com (Postfix) with ESMTP id A330E304075 for ; Mon, 19 May 2014 14:57:17 -0700 (PDT) Received: from ipmail07.adl2.internode.on.net (ipmail07.adl2.internode.on.net [150.101.137.131]) by cuda.sgi.com with ESMTP id 7t2vcUBOfYuYJ6Ou for ; Mon, 19 May 2014 14:57:11 -0700 (PDT) Date: Tue, 20 May 2014 07:56:58 +1000 From: Dave Chinner Subject: Re: [RFC PATCH 2/2] xfs: sysfs attributes for the current log state Message-ID: <20140519215658.GD8554@dastard> References: <1400263966-35541-1-git-send-email-bfoster@redhat.com> <1400263966-35541-3-git-send-email-bfoster@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1400263966-35541-3-git-send-email-bfoster@redhat.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Brian Foster Cc: xfs@oss.sgi.com On Fri, May 16, 2014 at 02:12:46PM -0400, Brian Foster wrote: > Create sysfs attributes to export the current runtime state of the log > to userspace. Note that the filesystem should be frozen for best > accuracy/consistency when reading these values, but is not required. > This is for testing and debug purposes only. > > Create the following per-mount attributes: log_head_lsn, log_tail_lsn, > reserve_head_lsn and write_head_lsn. These represent the physical log Reserve and write heads are not log sequence numbers (LSNs). A LSN is a cycle:block count tuple, while a grant head is a cycle:byte count tuple.... Calling the reserve_grant_head/write_grant_head would make more sense, I think, as would splitting them into cycle/byte output pairs. Splitting them make sense because if we increase the log size beyond 2GB we're going to need a different in-memory representation for the grant heads (i.e. need more than 32 bits for byte count), so we should probably handle that up front in the sysfs API... Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs