From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 30 May 2014 14:46:42 +0100 From: "Richard W.M. Jones" Message-ID: <20140530134642.GL1302@redhat.com> References: <20140522180405.GA6361@redhat.com> <20140522181334.GE1302@redhat.com> <20140529135246.GA31293@redhat.com> <20140529203410.GG1954@redhat.com> <20140529204719.GD1302@redhat.com> <20140529210648.GA3955@redhat.com> <20140529211955.GE1302@redhat.com> <20140529215815.GA4183@redhat.com> <20140530090422.GB31293@redhat.com> <20140530133814.GB8830@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20140530133814.GB8830@redhat.com> Subject: Re: [linux-lvm] Testing the new LVM cache feature Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Mike Snitzer Cc: Heinz Mauelshagen , Zdenek Kabelac , thornber@redhat.com, LVM general discussion and development I have now set both read_promote_adjustment == write_promote_adjustment == 0 and used drop_caches between runs. I also read Documentation/device-mapper/cache-policies.txt at Heinz's suggestion. I'm afraid the performance of the fio test is still not the same as the SSD (4.8 times slower than the SSD-only test now). Would repeated runs of (md5sum virt.* ; echo 3 > /proc/sys/vm/drop_caches) not eventually cause the whole file to be placed on the SSD? It does seem very counter-intuitive if not. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/