This is too bad. There is no other way around? It is a pitty that we
have to disable multicore in one of the few libraries where this is
available...
On 05/09/2017 14:39, Volker Braun wrote:
I disabled multithreading in openblas in #22021 as interrupting tends to
deadlock the thread pool:
commit eda96f33267984aaf82f96f759c654a185439c72
Merge: bb399086c4 026672777b
Author: Release Manager <rele...@sagemath.org>
Date: Sat Dec 24 20:58:34 2016 +0100
Trac #22021: OpenBLAS randomly crashes / deadlocks
Openblas occasionally crashes or deadlocks, most often in
`src/sage/matrix/matrix_integer_dense.pyx` but also other places. But
its always some longish linear algebra computation. Examples in the
comments.
URL: https://trac.sagemath.org/22021
Reported by: vbraun
Ticket author(s): Volker Braun
Reviewer(s): François Bissey
On Tuesday, September 5, 2017 at 6:43:32 PM UTC+2, tdumont wrote:
Hi,
I am doing some performances measurements with Sage/scipy.
It's matrix x matrix multiplication (not a very new benchmark....).
It appears that, on the same computer Sage version 8.0 uses Openblas
with multithreading, but not Sage version 8.1.beta3:
-Example (4 core, broadwell, 3.4ghz. Peak performance 217 Gflops !):
size of matrices: 640
-> Sage version 8.0 :
Gflops= 138.359946456 Portion peak perf = 0.6358 (top says %cpu=400)
-> Sage version 8.1.beta3:
Gflops= 48.5945679306 Portion peak perf = 0.2233 (%cpu=100)
Both of Sage versions where compiled from source.
My questions:
Will OpenBlas be fixed to 1 thread in the next versions of sage?
t.d.
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