From e62d6bade5099c02ebbb3c67c574d8f089475d3e Mon Sep 17 00:00:00 2001 From: Martin Quinson Date: Thu, 11 Jun 2020 01:38:20 +0200 Subject: [PATCH] Clarify one paragraph in the doc --- docs/source/Configuring_SimGrid.rst | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/docs/source/Configuring_SimGrid.rst b/docs/source/Configuring_SimGrid.rst index f581710337..029884cdca 100644 --- a/docs/source/Configuring_SimGrid.rst +++ b/docs/source/Configuring_SimGrid.rst @@ -965,9 +965,14 @@ this into account. For that, the actual duration is measured on the host machine and then scaled to the power of the corresponding simulated machine. The variable ``smpi/host-speed`` allows one to specify the computational speed of the host machine (in flop/s by -default) to use when scaling the execution times. It defaults to 20kf -(i.e., 20000 flop/s), but you really want to adjust it to get accurate -simulation results. +default) to use when scaling the execution times. + +The default value is ``smpi/host-speed=20kf`` (= 20,000 flop/s). This +is probably underestimated for most machines, leading SimGrid to +overestimate the amount of flops in the execution blocks that are +automatically injected in the simulator. As a result, the execution +time of the whole application will probably be overestimated until you +use a realistic value. When the code consists of numerous consecutive MPI calls, the previous mechanism feeds the simulation kernel with numerous tiny -- 2.20.1