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Re: [Qemu-devel] [v3 01/13] docs: Add a doc about multiple thread compre
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [v3 01/13] docs: Add a doc about multiple thread compression |
Date: |
Fri, 23 Jan 2015 08:24:35 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 |
On 12/11/2014 06:28 PM, Liang Li wrote:
> Give some details about the multiple compression threads and
> how to use it in live migration.
>
> Signed-off-by: Liang Li <address@hidden>
> Signed-off-by: Yang Zhang <address@hidden>
> ---
> docs/multi-thread-compression.txt | 141
> ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 141 insertions(+)
> create mode 100644 docs/multi-thread-compression.txt
>
> diff --git a/docs/multi-thread-compression.txt
> b/docs/multi-thread-compression.txt
> new file mode 100644
> index 0000000..3bbc641
> --- /dev/null
> +++ b/docs/multi-thread-compression.txt
> @@ -0,0 +1,141 @@
> +Use multiple thread (de)compression in live migration
> +======================================================
> +Copyright (C) 2014 Intel Corporation
You may want to include 2015 now.
> +Introduction
> +============
> +Instead of sending the guest memory directly, this solution will
> +compress the ram page before sending; after receiving, the data will
s/ram/RAM/
> +be decompressed. Using compression in live migration can help
> +to reduce the data transferred about 60%, this is very useful when the
> +bandwidth is limited, and the migration time can also be reduced about
> +70% in a typical case.
Of course, that's all dependent on memory having compressible contents.
An application that reads /dev/hwrng into a large amount of memory will
not be that compressible :)
> +
> +When to use the multiple thread compression in live migration
> +==============================================================
off-by-one on the divider length
> +Usage
> +=====
> +1. Verify both the source and destination QEMU are able
> +to support the multiple thread compression migration:
> + {qemu} info_migrate_capablilites
s/capablilites/capabilities/
> + {qemu} ... compress: off ...
> +
> +2. Activate compression on the souce:
s/souce/source/
> + {qemu} migrate_set_capability compress on
> +
> +3. Set the compression thread count on source:
> + {qemu} migrate_set_paramter compress_threads 12
s/paramter/parameter/
> +
> +The following is the default setting:
s/is...setting/are...settings/
> + compress: off
> + compress_threads: 8
> + decompress_threads: 2
> + compress_level: 1 (which means best speed)
> +
> +So, only the first two steps are required to use the multiple
> +thread compression in migration. You can do more if the default
> +setting is not appropriate.
s/setting is/settings are/
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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