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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

2016.01.29 15:48 "Re: OpenMP enabled libtiff", by Aaron Boxer

On Fri, Jan 29, 2016 at 9:46 AM, Bob Friesenhahn <
bfriesen@simple.dallas.tx.us> wrote:

> On Fri, 29 Jan 2016, Aaron Boxer wrote:
>
>>
>> Thanks. This is exactly the work flow I am interested in : tens of
>> thousands of ~10 MB TIFFs, accessed
>> sequentially.  Only 4 files would be open at a given time. So, even
>> though the files get closed, are you
>> suggesting I will see swapping in this case ?
>>
>
> It would not be true swapping or paging-out (actually, there could be some
> paging out to swap), but there will be memory pressure since memory mapping
> behaves as a cache.  The file data is still in memory (by default) after
> the file has been unmapped and memory pages are re-claimed (existing
> contents forgotten, and page re-purposed) for new activity based on new
> memory pressures, and the time the memory has remained inactive.
>
> The actual behavior is highly OS implementation dependent.
>
> On Unix type systems, the madvise() function can be used to help control
> behavior of memory-mapped data (e.g. MADV_DONTNEED), but again behavior is
> highly OS implementation dependent and the only way to know for sure is to
> test.
>
>
Thanks, Bob.  On windows, since there is no madvise function, wouldn't
reading a file and memory mapping the file both give the same result:  the
file gets cached in the OS file cache, causing memory pressure
when the cache gets filled up ?

Also, if madvise() is used on Unix, would that not degrade performance for
TIFF reading, since libtiff uses some random access to file, and file would
not be cached ?






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