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Re: [Qemu-devel] [PATCH v5 2/4 for-3.0] qcow2: Options' documentation fi
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH v5 2/4 for-3.0] qcow2: Options' documentation fixes |
Date: |
Thu, 26 Jul 2018 12:02:42 +0200 |
User-agent: |
Mutt/1.9.1 (2017-09-22) |
Am 25.07.2018 um 16:27 hat Leonid Bloch geschrieben:
> Signed-off-by: Leonid Bloch <address@hidden>
> ---
> 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"?
> @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.
> +(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."?
Kevin
[Qemu-devel] [PATCH v5 3/4] qcow2: Introduce an option for sufficient L2 cache for the entire image, Leonid Bloch, 2018/07/25
[Qemu-devel] [PATCH v5 4/4] iotests: Add tests for the new l2-cache-full option, Leonid Bloch, 2018/07/25