2017.02.06 20:43 "[Tiff] Qs about support for more than 2^16 IFDs and writing performance", by Dinesh Iyer

2017.02.07 00:58 "Re: [Tiff] Qs about support for more than 2^16 IFDs and writing performance", by Bob Friesenhahn

On 7.02.2017 2:04, Bob Friesenhahn wrote:

The linear scan is perhaps not the fastest algorithm but it should not take terribly long (much less than

> a second) to scan 65535 entries.e e

And if you multiply a second by 60,000, then you get many hours. Writing a TIFF file with 60,000 IFD-s will call TIFFLinkDirectory() 60,000 times.

Note that such files typically do not fit in L3 cache and thus traversing them may be extremely slow. We are talking mostly of BigTiff format here.

This sounds reasonable. We need a good test case for this (portable C source code) which be used to measure the performance impact and evaluate solutions.

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