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+===== Pin_T2C (theads to cores) =====
+==== Introduction ====
+**pin_t2c** is a homemade tool which let you set up and tune the CPU affinity for your jobs by pinning each app thread on a dedicated cpu. This can improve the global performance of a process by limiting, or even avoiding, cpu shiftings and cache/memory inherent recopies during your job.
+Some software comes with features for handling cpu affinity, but for all other software I recommand that you use **pin_t2c**.
+According to NAMD2 tests by Guillaume S., **pin_t2c** provides global performance improvements of around 40% on Lucifer nodes and 10% on Baal ones. Note for NAMD: the functionality provided by **pin_t2c** is basically the same as //+setcpuaffnity +pemap// optional NAMD2 parameters, so these should not be specified when using pin_t2c.
+Following standard usage, two main definitions (wordkeys) are used here:
+  * **socket** which represents here the physical processor ID/locator
+  * **cpu** which represents the physical/logical computing unit (a.k.a. core)
+To be able to use this commande in your job script or interactive session, please load the eponymous module before:
+<cli prompt="$ ">
+$ module load pin_t2c
+</cli>
+==== A few use cases ====
+First, you can just select all available resources on the system (or provided by Torque/CPUSETS mechanism), but pinning each thread on its cpu:
+<cli>
+$ myapp & pin_t2c --pid $!
+</cli>
+<note>Even if you have request a part of node(s), Pin_T2C is able to automatically access your job's CPUSETS properties and play with.</note>
+You can select which processor socket(s) to which you would like to restrict your process. The //--socket// parameter used by pin_t2c lets you forget about hardware specifities (e.g., how the cores are distributed between the processors).\\
+Here we're going to restrict our process to the first processor socket (ID: 0):
+<cli>
+$ myapp & pin_t2c --sockets 0 --pid $!
+</cli>
+//*: --sockets parameter is a processor socket list. This optional parameter must only contain a list of commas separated processor IDs (e.g 0,1).//
+If you are aware about hardware details (especially cores distribution on each socket), you can manually specify which CPUs (cores) you wish to restrict your process to.\\
+Here we're going to restrict our process to half the processor resources (all system cpus with a step size of 2):
+<cli>
+$ myapp & pin_t2c --cpus all:2 --pid $!
+</cli>
+//*: --cpus parameter is a cpu/core list. This optional parameter must contain a list of commas separated cpu/core IDs (e.g 0,1,2,3) or ranges (e.g 0-19) or ranges with step size (e.g 0-39:2).//
+You can manually select a part of each processor socket. In this case pin_t2c will automatically assign the correct cpus to each socket.\\
+Here, we're going to restrict our process to the 10 first cpus/cores from each socket:
+<cli>
+$ myapp & pin_t2c --sockets 0,1 --cpus 0-9 --pid $!
+</cli>
+<note important>If you specify a cpu/core list without any processor/socket parameter, cpu/core IDs are relative from system point of view (0:n:1, n is the total number of available cpus/cores on the system). However, if you have specified the –sockets parameter, the cpu/core IDs are from processor socket point of view (0:n:1, n is the number of available cpus/cores of each processor socket).</note>
+Other parameters and use cases are available with **pin_t2c**. Don't hesitate to consult the tool CLI help and test it:
+<cli>
+$ pin_t2c --help
+usage: pin_t2c [-h] [-s SOCKETS] [-c CPUS] [-f CPUSETFILE] [-r RUN] [-p PID]
+               [-d DELAY] [-v] [-n] [-V]
+pin_t2c provides an easy way to pin threads of a running process to hardware
+resources, specified or not.
+optional arguments:
+  -h, --help            show this help message and exit
+  -s SOCKETS, --sockets SOCKETS
+                        CPU socket list. This optional parameter must only
+                        contain a list of commas separated socket id (e.g
+,1).
+  -c CPUS, --cpus CPUS  cpu core list. This optional parameter must contain a
+                        list of commas separated core ids (e.g 0,1,2,3) or
+                        ranges (e.g 0-19) or ranges with step (e.g 0-39:2).
+  -f CPUSETFILE, --cpusetfile CPUSETFILE
+                        cpuset file describing your kernel cpuset mechanism
+                        (/dev/cpuset/...)
+  -r RUN, --run RUN     your shell command you need to execute
+  -p PID, --pid PID     your main process id you want to pin threads
+  -d DELAY, --delay DELAY
+                        delay between each pinning
+  -v, --verbose         increase output verbosity
+  -n, --dry-run         show what would have been pinned and how
+  -V, --version         Prints the pin_t2c version number of the executable
+                        and exits.
+</cli>
+<note>Note than if you want to kill **pin_t2c** (which is not running in background itself) by pressing Ctrl+C, you will kill **pin_t2c** __and__ your main process at the same time.</note>