From: Eric Blake <eblake@redhat.com>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
qemu-devel@nongnu.org, qemu-block@nongnu.org
Cc: mreitz@redhat.com, kwolf@redhat.com, stefanha@redhat.com, den@openvz.org
Subject: Re: [Qemu-devel] [PATCH v2] qcow2: do not allocate extra memory
Date: Thu, 14 Jul 2016 12:32:03 -0600 [thread overview]
Message-ID: <5787DAA3.3020005@redhat.com> (raw)
In-Reply-To: <1468515565-81313-1-git-send-email-vsementsov@virtuozzo.com>
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On 07/14/2016 10:59 AM, Vladimir Sementsov-Ogievskiy wrote:
> There are no needs to allocate more than one cluster, as we set
> avail_out for deflate to one cluster.
>
> Zlib docs (http://www.zlib.net/manual.html) says:
> "deflate compresses as much data as possible, and stops when the input
> buffer becomes empty or the output buffer becomes full."
>
> So, deflate will not write more than avail_out to output buffer. If
> there is no enough space in output buffer for compressed data (it may be
s/no/not/
> larger than input data) deflate just returns Z_OK. (if all data is
> compressed and written to output buffer deflate returns Z_STREAM_END).
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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next prev parent reply other threads:[~2016-07-14 18:32 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-14 16:59 [Qemu-devel] [PATCH v2] qcow2: do not allocate extra memory Vladimir Sementsov-Ogievskiy
2016-07-14 18:32 ` Eric Blake [this message]
2016-07-14 19:04 ` [Qemu-devel] [Qemu-block] " John Snow
2016-07-15 12:49 ` [Qemu-devel] " Max Reitz
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