From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Layton Subject: Re: IOzone testing Date: Sat, 26 Sep 2009 08:36:39 -0400 Message-ID: <4ABE0AD7.7000904@att.net> References: <4ABE0553.3090502@att.net> Reply-To: NILFS Users mailing list Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: users-bounces-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org Errors-To: users-bounces-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org To: NILFS Users mailing list J=E9r=F4me Poulin wrote: > On Sat, Sep 26, 2009 at 8:13 AM, Jeff Layton wrote: > = >> Good morning, >> >> I'm running IOzone on a NILFS2 partition and it's running alot >> slower that I had expected. I'm pretty sure it's because of the >> checkpoints. I can change the protection_period to something >> very small (or zero). Would that improve the performance? >> >> = > The protection period only affects how the cleaner daemon will clean > the old checkpoints, if 0 I guess it will just clean them up as soon > as it can but it won't stop creating them. You could, just for > benchmark purpose, kill nilfs_cleanerd which will stop checkpoint > related activities. > = It will only stop the clean up of checkpoints outside of policy - correct? So it won't stop them from being created but it will stop the cleaning = process. >> In addition, is there a way to turn off checkpointing? >> >> = > The whole filesystem is based on those checkpoint, the fact that it is > a log filesystem makes it so all writes are made at the end of the > device, and when a write is complete, a checkpoint is made. > = Understood. But for benchmarks like IOzone where you are creating files and most likely syncing, this will trigger a checkpoint. I haven't looked too much at IOzone but it might even be causing a sync after each record right, again forcing a checkpoint. So I was looking for some way to control how often checkpoints are created - something like the protection_period option for the GC. But I understand that the checkpoint is a part of the design of the file system. Thanks! Jeff