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January 2016

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2016.01.25 18:25 "OpenMP enabled libtiff", by Aaron Boxer
2016.01.25 19:05 "Re: OpenMP enabled libtiff", by Aaron Boxer
2016.01.25 19:17 "Re: OpenMP enabled libtiff", by <kandel3@illinois.edu>
2016.01.25 19:18 "Re: OpenMP enabled libtiff", by Bob Friesenhahn
2016.01.25 20:21 "Re: OpenMP enabled libtiff", by Aaron Boxer
2016.01.25 20:45 "Re: OpenMP enabled libtiff", by Bob Friesenhahn
2016.01.25 23:27 "Re: OpenMP enabled libtiff", by <kandel3@illinois.edu>
2016.01.26 09:12 "Re: OpenMP enabled libtiff", by <jcupitt@gmail.com>
2016.01.26 13:45 "Re: OpenMP enabled libtiff", by Aaron Boxer
2016.01.26 14:46 "Re: OpenMP enabled libtiff", by Olivier Paquet
2016.01.26 16:01 "Re: OpenMP enabled libtiff", by Aaron Boxer
2016.01.26 17:10 "Re: OpenMP enabled libtiff", by Bob Friesenhahn
2016.01.26 19:32 "Re: OpenMP enabled libtiff", by Aaron Boxer
2016.01.26 19:29 "Re: OpenMP enabled libtiff", by Aaron Boxer
2016.01.26 20:36 "Re: OpenMP enabled libtiff", by Bob Friesenhahn
2016.01.27 18:32 "Re: OpenMP enabled libtiff", by Aaron Boxer
2016.01.27 19:55 "Re: OpenMP enabled libtiff", by Bob Friesenhahn
2016.01.29 13:28 "Re: OpenMP enabled libtiff", by Aaron Boxer
2016.01.29 14:46 "Re: OpenMP enabled libtiff", by Bob Friesenhahn
2016.01.29 15:48 "Re: OpenMP enabled libtiff", by Aaron Boxer
2016.01.29 15:49 "Re: OpenMP enabled libtiff", by Aaron Boxer
2016.01.29 18:12 "Re: OpenMP enabled libtiff", by Bob Friesenhahn
2016.01.26 09:36 "Re: OpenMP enabled libtiff", by Mat Maher
2016.01.26 09:52 "Re: OpenMP enabled libtiff", by Even Rouault
2016.01.26 14:22 "Re: OpenMP enabled libtiff", by Fred Rothganger
2016.01.27 18:51 "Re: OpenMP enabled libtiff", by Larry Gritz

2016.01.25 20:21 "Re: OpenMP enabled libtiff", by Aaron Boxer

Hi Bob,

On Mon, Jan 25, 2016 at 2:18 PM, Bob Friesenhahn <
bfriesen@simple.dallas.tx.us> wrote:

> On Mon, 25 Jan 2016, Aaron Boxer wrote:
>
> Is anyone interested in having OpenMP support in libtiff ?
>> Is this feasible?  I am planning on adding this feature for another
>> project
>> I am working on, so I am trying to gauge interest.
>>
>
> What would the OpenMP support do?  Few operations in libtiff are CPU
> bound.  Only compressed formats consume noticeable CPU.
>

I believe SSDs perform well under multiple reads, but this would have to be
carefully bench-marked, of course.



>
> It is useful for OpenMP (or any other sort of threading) to be used by an
> application using libtiff to perform parallel operations.  For example,
> reading or writing several strips/tiles at once.
>
> Currently there is no locking in libtiff and no support for
> thread-specific data (TSD).  There are just a few static/global variables.
> Features like strip-chopping likely cause serious issues for threading
> since they require storing intermediate state.
>
> If support for any necessary locking or TSD is added, then it should be
> added in a generic way so that the locks and TSD APIs are provided by the
> invoking environment and don't need to be baked into libtiff.
>

Thanks.  One easy way might be to partition ahead of time which strips are
processed by which threads. I will take a look at the code and see if I can
come up with a simple way of doing this.

Cheers,
Aaron




>
> Bob
> --
> Bob Friesenhahn
> bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
> GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/