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Re: [Qemu-block] [PATCH 1/2] qcow2: Give the refcount cache the minimum
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From: |
Alberto Garcia |
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Subject: |
Re: [Qemu-block] [PATCH 1/2] qcow2: Give the refcount cache the minimum possible size by default |
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Date: |
Tue, 13 Mar 2018 19:48:24 +0100 |
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User-agent: |
Notmuch/0.18.2 (http://notmuchmail.org) Emacs/24.4.1 (i586-pc-linux-gnu) |
On Tue 13 Mar 2018 07:23:36 PM CET, Eric Blake wrote:
>> + *refcount_cache_size =
>> + MIN(combined_cache_size, min_refcount_cache);
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> but here, if combined_cache_size is smaller than min_refcount_cache,
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>> + *l2_cache_size = combined_cache_size - *refcount_cache_size;
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> then l2_cache_size is set to a negative value.
No, it's set to 0.
If combined == 4k and min_refcount == 256, then
refcount_cache_size = MIN(4k, 256k) // 4k
l2_cache_size = 4k - 4k; // 0
Then the caller ensures that it's always set to the minimum (as it did
with the previous code).
Berto