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Feb 21

Protected: logs and metrics made easy with OVH

Posted on February 21, 2021 by Pascal

There is no excerpt because this is a protected post.

Posted in Pascal's diary, Uncategorized | Tagged logs, metrics, ovh | Enter your password to view comments.
Sep 19

Crystals – building made easy

Posted on September 19, 2016 by Pascal

Crystals is fully open source since a few years but building from source was always a tedious task. After many years, improvements have been made. The old Linux Makefiles and windows bat files have been replaced with cmake. The same … Continue reading →

Posted in Uncategorized | Tagged crystals
Jul 09

Compression and crystallograpic 2D images

Posted on July 9, 2014 by Pascal

Since the apparition of area detectors, the storage of the frames resulting of the experiment has always been troublesome. The apparition of bigger and faster detectors increased the problem where a lots of big images are produced. Several methods exist … Continue reading →

Posted in Pascal's diary | Tagged optimization
Sep 06

eigenvalue decomposition benchmark

Posted on September 6, 2013 by Pascal

After looking at the Cholesky factorization problem, time to have a look at the eigenvalue decomposition of a symmetric matrix. Depending on the function and the blas library used, lots of differences appear. The functions which are benchmarked here are: … Continue reading →

Posted in Pascal's diary
Sep 01

Lapack and packed storage

Posted on September 1, 2013 by Pascal

Crystals is using packed storage to store symmetric matrices. Packed storage is using a linear array to store only the unique data (Netlib packed storage). There is a huge penalty on the calculation by doing so in some cases. In … Continue reading →

Posted in Pascal's diary | Tagged optimization
Aug 15

reading/writing byte offset compression in cbf

Posted on August 15, 2013 by Pascal

The compression scheme “byte offset” is commonly used in frames encoded in cbf. The Pilatus hybrid pixel detectors are using this format. The algorithm is descrived here: http://www.bernstein-plus-sons.com/software/CBF/doc/CBFlib.html#3.3 and a library already exist to manipulate cbf files called cbflib. The … Continue reading →

Posted in Pascal's diary | Tagged Fortran
May 17

Parallel structure factors calculation

Posted on May 17, 2013 by Pascal

As part of my new position in Oxford, I have a new computer: An 8-cores Intel Xeon CPU E5-2665 with 16GB of memory. Enough cores to try if my library is scaling well in multi-threaded environments. The result is really … Continue reading →

Posted in Pascal's diary | Tagged optimization
Apr 14

autovectorization: “not vectorized: not suitable for gather”

Posted on April 14, 2013 by Pascal

The cryptic warning “not vectorized: not suitable for gather” is from a report of gfortran on auto-vectorization. For a long time, gfortran was reporting this failed optimization on a very simple mathematical operation. I managed to find the cause today … Continue reading →

Posted in Pascal's diary | Tagged optimization
Feb 10

Fortran weakness: byte wise I/O

Posted on February 10, 2013 by Pascal

In the Crm² lab, in Nancy (France), we have prototype of an hybrid pixel detector from the company Imxpad. The data from the detector are raw ASCII files that I need to convert into files suitable for integration software. We … Continue reading →

Posted in Pascal's diary | Tagged optimization
Dec 17

CPU evolution, an increase in complexity

Posted on December 17, 2012 by Pascal

Moore’s law has driven computing power for years and will probably continue for sometime even though it ends is coming. However, if during the first 20 years the increasing power was directly related to the frequency, it’s no longer the … Continue reading →

Posted in Pascal's diary | Tagged optimization
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