From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34319) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fihFJ-0002X0-3x for qemu-devel@nongnu.org; Thu, 26 Jul 2018 10:28:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fihFG-0000t7-3J for qemu-devel@nongnu.org; Thu, 26 Jul 2018 10:28:01 -0400 References: <20180725142758.9980-1-lbloch@janustech.com> <20180725142758.9980-3-lbloch@janustech.com> <20180726100242.GD4215@localhost.localdomain> From: Leonid Bloch Message-ID: <5188afdb-8486-5fcf-27d4-c627a382291b@janustech.com> Date: Thu, 26 Jul 2018 17:27:14 +0300 MIME-Version: 1.0 In-Reply-To: <20180726100242.GD4215@localhost.localdomain> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB-large Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v5 2/4 for-3.0] qcow2: Options' documentation fixes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz , Eric Blake On 07/26/2018 01:02 PM, Kevin Wolf wrote: > Am 25.07.2018 um 16:27 hat Leonid Bloch geschrieben: >> Signed-off-by: Leonid Bloch >> --- >> docs/qcow2-cache.txt | 3 +++ >> qemu-options.hx | 10 ++++++---- >> 2 files changed, 9 insertions(+), 4 deletions(-) >> >> diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt >> index 8a09a5cc5f..3673f2be0e 100644 >> --- a/docs/qcow2-cache.txt >> +++ b/docs/qcow2-cache.txt >> @@ -130,6 +130,9 @@ 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. >> >> +- At most two of "l2-cache-size", "refcount-cache-size", and "cache-size" >> + can be set simultaneously. > > The indentation is off here, the other list items have one space more. > >> 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 >> diff --git a/qemu-options.hx b/qemu-options.hx >> index b1bf0f485f..13ece21cb6 100644 >> --- a/qemu-options.hx >> +++ b/qemu-options.hx >> @@ -752,15 +752,17 @@ image file) >> >> @item cache-size >> The maximum total size of the L2 table and refcount block caches in bytes >> -(default: 1048576 bytes or 8 clusters, whichever is larger) > > I think it would be good to still say something about the default. > Maybe something like "default: the sum of l2-cache-size and > refcount-cache-size"? Yes, that sounds good! > >> @item l2-cache-size >> -The maximum size of the L2 table cache in bytes >> -(default: 4/5 of the total cache size) >> +The maximum size of the L2 table cache. > > Why did you remove "in bytes" and add a period which the other options > don't have? I prefer the old version of this line. I removed "in bytes" because it also accepts k, M, G, ... but on a second thought, these are amounts of bytes as well, so changing back to the old version. >> +(default: if cache-size is not defined - 1048576 bytes or 8 clusters, whichever >> +is larger; otherwise, as large as possible or needed within the cache-size, >> +while permitting the requested or the minimal refcount cache size) >> >> @item refcount-cache-size >> The maximum size of the refcount block cache in bytes >> -(default: 1/5 of the total cache size) >> +(default: 4 times the cluster size, or any portion of the cache-size, if it is >> +specified and large enough, left over after allocating the full L2 cache) > > I found the second part hard to understand. Maybe "4 times the cluster > size; or if both cache-size and l2-cache-size are given, the part of > the cache-size that is not used for the L2 cache yet."? That is not accurate. Because even if l2-cache-size is not given and cache-size is large enough to accommodate enough L2 cache to cover the entire image, plus the minimal amount of refcount cache with room to spare - refcount cache will use all the rest of the cache-size. How about: "default: 4 times the cluster size; or if cache-size is specified, the part of it which is not used for the L2 cache" Leonid. > Kevin >