Update SLURM instructions in fox

We no longer need to use srun to enter the allocated machine. Make sure
that the default allocation time is also specified.

content/fox/_index.md

@@ -22,19 +22,16 @@ the detailed specifications:
 ## Access
 
 To access the machine, request a SLURM session from [apex](/apex) using the `fox`
-partition. If you need the machine for performance measurements, use an
-exclusive reservation:
+partition and set the time for the reservation (the default is 1 hour). If you
+need the machine for performance measurements, use an exclusive reservation:
 
-    apex% salloc -p fox --exclusive
+    apex% salloc -p fox -t 02:00:00 --exclusive
+    fox%
 
 Otherwise, specify the CPUs that you need so other users can also use the node
 at the same time:
 
-    apex% salloc -p fox -c 8
-
-Then use srun to execute an interactive shell:
-
-    apex% srun --pty $SHELL
+    apex% salloc -p fox -t 02:00:00 -c 8
     fox%
 
 Make sure you get all CPUs you expect:
@@ -46,55 +43,38 @@ Follow [these steps](/access) if you don't have access to apex or fox.
 
 ## CUDA
 
-To use CUDA, you can use the following `flake.nix` placed in a new directory to
-load all the required dependencies:
+To use CUDA you'll need to load the NVIDIA `nvcc` compiler and some additional
+libraries in the environment. Clone the 
+[following
+example](https://jungle.bsc.es/git/rarias/devshell/src/branch/main/cuda) and
+modify the `flake.nix` if needed to add additional packages.
 
-```nix
-{
-  inputs.jungle.url = "jungle";
+Then just run `nix develop` from the same directory to spawn a new shell with
+the CUDA environment:
 
-  outputs = { jungle, ... }: {
-    devShell.x86_64-linux = let
-      pkgs = jungle.nixosConfigurations.fox.pkgs;
-    in pkgs.mkShell {
-      name = "cuda-env-shell";
-      buildInputs = with pkgs; [
-        git gitRepo gnupg autoconf curl
-        procps gnumake util-linux m4 gperf unzip
+    fox% git clone https://jungle.bsc.es/git/rarias/devshell
 
-        # Cuda packages (more at https://search.nixos.org/packages)
-        cudatoolkit linuxPackages.nvidia_x11
-        cudaPackages.cuda_cudart.static
-        cudaPackages.libcusparse
+    fox% cd devshell/cuda
 
-        libGLU libGL
-        xorg.libXi xorg.libXmu freeglut
-        xorg.libXext xorg.libX11 xorg.libXv xorg.libXrandr zlib
-        ncurses5 stdenv.cc binutils
-      ];
-      shellHook = ''
-        export CUDA_PATH=${pkgs.cudatoolkit}
-        export LD_LIBRARY_PATH=/var/run/opengl-driver/lib
-        export SMS=50
-      '';
-    };
-  };
-}
-```
+    fox% nix develop
 
-Then just run `nix develop` from the same directory:
-
-    % mkdir cuda
-    % cd cuda
-    % vim flake.nix
-    [...]
-    % nix develop
-    $ nvcc -V
+    fox$ nvcc -V
     nvcc: NVIDIA (R) Cuda compiler driver
-    Copyright (c) 2005-2024 NVIDIA Corporation
-    Built on Tue_Feb_27_16:19:38_PST_2024
-    Cuda compilation tools, release 12.4, V12.4.99
-    Build cuda_12.4.r12.4/compiler.33961263_0
+    Copyright (c) 2005-2025 NVIDIA Corporation
+    Built on Fri_Feb_21_20:23:50_PST_2025
+    Cuda compilation tools, release 12.8, V12.8.93
+    Build cuda_12.8.r12.8/compiler.35583870_0
+
+    fox$ make
+    nvcc -ccbin g++ -m64 -Wno-deprecated-gpu-targets -o cudainfo cudainfo.cpp
+
+    fox$ ./cudainfo
+    ./cudainfo Starting...
+
+     CUDA Device Query (Runtime API) version (CUDART static linking)
+
+    Detected 2 CUDA Capable device(s)
+    ...
 
 ## AMD uProf