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Re: [Qemu-devel] [PATCH v7 1/9] qcow2: Options' documentation fixes
From: |
Alberto Garcia |
Subject: |
Re: [Qemu-devel] [PATCH v7 1/9] qcow2: Options' documentation fixes |
Date: |
Fri, 10 Aug 2018 13:50:03 +0200 |
User-agent: |
Notmuch/0.18.2 (http://notmuchmail.org) Emacs/24.4.1 (i586-pc-linux-gnu) |
On Fri 10 Aug 2018 08:26:39 AM CEST, Leonid Bloch wrote:
> Signed-off-by: Leonid Bloch <address@hidden>
> ---
> docs/qcow2-cache.txt | 16 +++++++++++-----
> qemu-options.hx | 9 ++++++---
> 2 files changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt
> index 8a09a5cc5f..0f157d859a 100644
> --- a/docs/qcow2-cache.txt
> +++ b/docs/qcow2-cache.txt
> @@ -97,12 +97,15 @@ need:
> l2_cache_size = disk_size_GB * 131072
> refcount_cache_size = disk_size_GB * 32768
>
> -QEMU has a default L2 cache of 1MB (1048576 bytes) and a refcount
> -cache of 256KB (262144 bytes), so using the formulas we've just seen
> -we have
> +With the default cluster size, to cover each 8 GB of the virtual image
> +size, 1MB of L2 cache is needed:
>
> - 1048576 / 131072 = 8 GB of virtual disk covered by that cache
> - 262144 / 32768 = 8 GB
> + 65536 / 8 = 8192 = 8 GB / 1 MB
Where does this 65536 / 8 come from? The line that you changed follows
directly from the formula immediately before that paragraph:
l2_cache_size = disk_size_GB * 131072
that is
l2_cache_size / 131072 = disk_size_GB
1048576 / 131072 = 8 GB
Berto
- [Qemu-devel] [PATCH v7 0/9] Take the image size into account when allocating the L2 cache, Leonid Bloch, 2018/08/10
- [Qemu-devel] [PATCH v7 1/9] qcow2: Options' documentation fixes, Leonid Bloch, 2018/08/10
- Re: [Qemu-devel] [PATCH v7 1/9] qcow2: Options' documentation fixes,
Alberto Garcia <=
- [Qemu-devel] [PATCH v7 2/9] qcow2: Cosmetic changes, Leonid Bloch, 2018/08/10
- [Qemu-devel] [PATCH v7 3/9] qcow2: Make sizes more humanly readable, Leonid Bloch, 2018/08/10
- [Qemu-devel] [PATCH v7 4/9] qcow2: Avoid duplication in setting the refcount cache size, Leonid Bloch, 2018/08/10
- [Qemu-devel] [PATCH v7 5/9] qcow2: Assign the L2 cache relatively to the image size, Leonid Bloch, 2018/08/10