[Libguestfs] [PATCH nbdkit] vddk: Relax threading model and enable multi-conn.

[Eric Blake]

On 8/5/20 8:32 AM, Richard W.M. Jones wrote:
> On Wed, Aug 05, 2020 at 08:12:26AM -0500, Eric Blake wrote:
>> On 8/5/20 7:48 AM, Richard W.M. Jones wrote:
>>> See comment in code and
>>> https://www.redhat.com/archives/libguestfs/2020-August/msg00023.html
>>> ---
>>>   plugins/vddk/vddk.c | 32 ++++++++++++++++++++++++++++----
>>>   1 file changed, 28 insertions(+), 4 deletions(-)
>>
>> I'll have to trust your testing, but code-wise, this looks safe.
> 
> I'm in a bit two minds about this one.  It appears safe.  OTOH it's
> somewhat risky in theory, and it doesn't give us very much performance
> improvement.

I agree that we are NOT strictly following the VDDK documentation, in 
that this risks 2 different threads calling VDiskLib_Open (even though 
we have serialized it so that only one open is ever active at a time). 
So it is indeed risky.

> 
> Let's discuss alternate implementations with Nir in the other thread.

I'll respond there.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org