From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41353) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fhz8Q-0002dq-Nn for qemu-devel@nongnu.org; Tue, 24 Jul 2018 11:21:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fhz8P-0007rv-JB for qemu-devel@nongnu.org; Tue, 24 Jul 2018 11:21:58 -0400 References: <20180724121753.5753-1-lbloch@janustech.com> <20180724121753.5753-4-lbloch@janustech.com> From: Eric Blake Message-ID: <8b2636b3-6871-c68a-f103-0f2f150d3e7e@redhat.com> Date: Tue, 24 Jul 2018 10:21:50 -0500 MIME-Version: 1.0 In-Reply-To: <20180724121753.5753-4-lbloch@janustech.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 3/4] docs: Document the l2-cache-full option List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Leonid Bloch , qemu-devel@nongnu.org Cc: Kevin Wolf , qemu-block@nongnu.org, Max Reitz On 07/24/2018 07:17 AM, Leonid Bloch wrote: > Signed-off-by: Leonid Bloch > --- > docs/qcow2-cache.txt | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt > index a0a1267482..43c0faaddb 100644 > --- a/docs/qcow2-cache.txt > +++ b/docs/qcow2-cache.txt > @@ -110,11 +110,12 @@ How to configure the cache sizes > Cache sizes can be configured using the -drive option in the > command-line, or the 'blockdev-add' QMP command. > > -There are three options available, and all of them take bytes: > +There are four options available: > > -"l2-cache-size": maximum size of the L2 table cache > -"refcount-cache-size": maximum size of the refcount block cache > -"cache-size": maximum size of both caches combined > +"l2-cache-size": maximum size of the L2 table cache (bytes, K, M) > +"refcount-cache-size": maximum size of the refcount block cache (bytes, K, M) > +"cache-size": maximum size of both caches combined (bytes, K, M) > +"l2-cache-full": make the L2 cache cover the full image (boolean) > > There are a few things that need to be taken into account: > Worth mentioning that the first three can be combined (although usually you'll never specify more than 2; as specifying all 3 requires that you perform the correct addition), but that the third is mutually exclusive? > @@ -130,6 +131,9 @@ There are a few things that need to be taken into account: > memory as possible to the L2 cache before increasing the refcount > cache size. > > +- If "l2-cache-full" is specified, QEMU will assign enough memory > + to the L2 cache to cover the entire size of the image. > + > Unlike L2 tables, refcount blocks are not used during normal I/O but > only during allocations and internal snapshots. In most cases they are > accessed sequentially (even during random guest I/O) so increasing the > -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org