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Re: [Qemu-block] [PATCH] qcow2: Optimize L2 table cache size based on im
From: |
Ed Swierk |
Subject: |
Re: [Qemu-block] [PATCH] qcow2: Optimize L2 table cache size based on image and cluster sizes |
Date: |
Tue, 4 Oct 2016 08:36:31 -0700 |
On Tue, Oct 4, 2016 at 7:31 AM, Alberto Garcia <address@hidden> wrote:
> That might be a lot of memory if the image is big. 1 TB qcow2 image ==
> 128 MB L2 cache.
>
> See https://bugzilla.redhat.com/show_bug.cgi?id=1377735#c2
>
> If we want to add this feature, I think I'd rather make it explicit.
I agree explicit is generally better than automagical, but unlike say
the VM RAM size, the qcow L2 table cache is an implementation detail
no user should be expected to know exists, let alone needs tweaking
according to a specific formula to avoid an arbitrary performance
cliff.
At least giving users a way to skip the math would be an improvement.
Would you be okay with an explicitly-set option like
l2_cache_size=auto or =max that optimizes for performance at the
expense of memory?
--Ed
- [Qemu-block] [PATCH] qcow2: Optimize L2 table cache size based on image and cluster sizes, Ed Swierk, 2016/10/04
- Re: [Qemu-block] [PATCH] qcow2: Optimize L2 table cache size based on image and cluster sizes, Alberto Garcia, 2016/10/04
- Re: [Qemu-block] [PATCH] qcow2: Optimize L2 table cache size based on image and cluster sizes,
Ed Swierk <=
- Re: [Qemu-block] [PATCH] qcow2: Optimize L2 table cache size based on image and cluster sizes, Max Reitz, 2016/10/04
- Re: [Qemu-block] [PATCH] qcow2: Optimize L2 table cache size based on image and cluster sizes, Alberto Garcia, 2016/10/05
- Re: [Qemu-block] [PATCH] qcow2: Optimize L2 table cache size based on image and cluster sizes, Max Reitz, 2016/10/05
- Re: [Qemu-block] [PATCH] qcow2: Optimize L2 table cache size based on image and cluster sizes, Alberto Garcia, 2016/10/05
- Re: [Qemu-block] [PATCH] qcow2: Optimize L2 table cache size based on image and cluster sizes, Max Reitz, 2016/10/05
- Re: [Qemu-block] [PATCH] qcow2: Optimize L2 table cache size based on image and cluster sizes, Alberto Garcia, 2016/10/06
- Re: [Qemu-block] [PATCH] qcow2: Optimize L2 table cache size based on image and cluster sizes, Kevin Wolf, 2016/10/05
[Qemu-block] [PATCH v2] qcow2: Add cache-size=max option to optimize caches for performance, Ed Swierk, 2016/10/04