Re: [Qemu-block] [PATCH v2 0/7] curl: locking cleanups/fixes, coroutine conversion, remove aio_poll

[Max Reitz]

On 2017-05-10 17:57, Richard W.M. Jones wrote:
> On Wed, May 10, 2017 at 04:31:58PM +0200, Paolo Bonzini wrote:
>> Since the last patch in v1 didn't work, I bit the bullet and converted
>> the whole thing to coroutines (patches 4-6).  This in turns allows a more
>> elegant solution to wait for CURLStates to get free (patch 7).
>>
>> I tested this by lowering CURL_NUM_STATES to 2.  With this change, the
>> buggy case triggers a couple times while booting a Fedora netinst image.
> 
> This series fixes the original bug, so:
> 
>   Tested-by: Richard W.M. Jones <address@hidden>
> 
> I think the Reported-by in patch 3 should credit Kun Wei for finding
> the bug, and we should probably mention the BZ too:
> 
>   Reported-by: Kun Wei <address@hidden>
>   Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1447590

This one is older, though:
https://bugzilla.redhat.com/show_bug.cgi?id=1437393

:-)

Max

> A nit pick perhaps but in patch 5 you say "This was broken before for
> disks > 2TB, but now it would break at 4GB.".
> I understand after reading it a few times that you mean it would be
> broken at 4GB, if you hadn't changed size_t -> uint64_t (on 32 bit
> platforms).  Perhaps better to clarify that sentence.
> 
> ---
> 
> I also ran some performance and stability testing.  I used virt-ls for
> this.  The following command will iterate over every file in a remote
> guest image and print an md5sum:
> 
>   LIBGUESTFS_BACKEND=direct \
>   LIBGUESTFS_HV=~/d/qemu/x86_64-softmmu/qemu-system-x86_64 \
>   virt-ls -a http://somehost/rhel-guest-image-7.1-20150224.0.x86_64.qcow2 \
>           -lR --checksum /
> 
> I timed this with and without your patches, but there was no
> significant difference (but note that virt-ls is a fundamentally
> sequential program).
> 
> It didn't crash or hang at any time during my testing.
> 
> Rich.
>

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