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Date: Tue, 28 Aug 2018 15:16:56 +0200
From: Matus UHLAR - fantomas <>
Subject: Re: Beignet: unable to find good values for

>On 2018-08-27 11:54, Matus UHLAR - fantomas wrote:
>>for a few weeks, the beignet OpenCL driver reports this message:
>>Loaded 1 password hash (mysql-sha1-opencl, MySQL 4.1+ [SHA1 OpenCL])
>>Beignet: "unable to find good values for local_work_size[i], please
>>provide\n" " local_work_size[] explicitly, you can find good values with\n"
>>" trial-and-error method."
>>I understand it as the driver does not provide any useful value and 
>>the john
>>is just guesssing.
>>How can I test for the proper value? can I do it at runtime?

On 27.08.18 19:36, magnum wrote:
>That message comes from Beignet, not john. What is triggering it is 
>likely that we deliberately use a local work size of NULL for 
>incomplete batches (eg. the very last batch in a session). There's not 
>really any way you can provide it... short of reverting to some commit 
>before where 
>we had another scheme (which had other problems).
>I would report it to them as a bug, because according to the OpenCL 
>spec. it should handle it. I believe what most drivers/runtimes do is 
>find greatest divisor of GWS that is less than or equal to highest 
>possible LWS, and use that.
>Does it crash/abort or is this just a warning message? It could be 
>that it simply warns and then use an LWS of 1 which is suboptimal but 
>works fine in this case.

since the cracking seems to continue, it is apparently just a warning, so I
will ignore it for now.

Thanks for explanation
Matus UHLAR - fantomas, ;
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