How to have cpuminer use all CPUs on FreeBSD

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Situation

You're trying to mine some cryptocoins on your FreeBSD box. Unfortunately, the mining process seems to occur on only one CPU, despite cpuminer creating and binding threads.

[2014-03-23 01:41:53] 8 miner threads started, using 'X11' algorithm.
[2014-03-23 01:41:53] Starting Stratum on stratum+tcp://drkpool.com:3333
[2014-03-23 01:41:53] Binding thread 0 to cpu 0
[2014-03-23 01:41:53] Binding thread 1 to cpu 1
[2014-03-23 01:41:53] Binding thread 2 to cpu 2
[2014-03-23 01:41:53] Binding thread 3 to cpu 3
[2014-03-23 01:41:53] Binding thread 4 to cpu 4
[2014-03-23 01:41:53] Binding thread 5 to cpu 5
[2014-03-23 01:41:53] Binding thread 6 to cpu 6
[2014-03-23 01:41:53] Binding thread 7 to cpu 7
[2014-03-23 01:41:56] Stratum detected new block

Using ktrace yields some information. The thread-cpu binding is failing.

 23429 minerd   CALL  write(0x2,0x7fffff5fa660,0x30)
 23429 minerd   GIO   fd 2 wrote 48 bytes
       "[2014-03-23 00:45:32] Binding thread 1 to cpu 1
       "
 23429 minerd   RET   write 48/0x30
 23429 minerd   CALL  _umtx_op(0x803019060,0x16,0,0,0)
 23429 minerd   RET   _umtx_op 0
 23429 minerd   CALL  cpuset_setaffinity(0x3,0x3,0xffffffffffffffff,0x10,0x7fffff5faf70)
 23429 minerd   RET   cpuset_setaffinity -1 errno 11 Resource deadlock avoided
 23429 minerd   CALL  nanosleep(0x7fffff5fad90,0x7fffff5fad80)
 23429 minerd   RET   _umtx_op 0
 23429 minerd   CALL  mmap(0,0x400000,0x3,0x1002,0xffffffff,0)
 23429 minerd   RET   mmap 34431041536/0x804400000
 23429 minerd   CALL  _umtx_op(0x803019060,0x16,0,0,0)
 23429 minerd   RET   _umtx_op 0

Solution

Use cpuset to change the affinity of the process once it's launched.

cpuset -c -l 0-15 -p 3044

Adapt the command to your number of CPUs and the PID of your miner process.

See kern/163585 for more information.

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