NUMA support

Summary:
The aim here is to reduce the number of remote memory accesses on
systems with a NUMA memory architecture, typically multi-socket servers.

Linux provides a NUMA API for doing two things:
* Allocating memory local to a particular node
* Binding a thread to a particular node

When given the +RTS --numa flag, the runtime will
* Determine the number of NUMA nodes (N) by querying the OS
* Assign capabilities to nodes, so cap C is on node C%N
* Bind worker threads on a capability to the correct node
* Keep a separate free lists in the block layer for each node
* Allocate the nursery for a capability from node-local memory
* Allocate blocks in the GC from node-local memory

For example, using nofib/parallel/queens on a 24-core 2-socket machine:

```
$ ./Main 15 +RTS -N24 -s -A64m
  Total   time  173.960s  (  7.467s elapsed)

$ ./Main 15 +RTS -N24 -s -A64m --numa
  Total   time  150.836s  (  6.423s elapsed)
```

The biggest win here is expected to be allocating from node-local
memory, so that means programs using a large -A value (as here).

According to perf, on this program the number of remote memory accesses
were reduced by more than 50% by using `--numa`.

Test Plan:
* validate
* There's a new flag --debug-numa=<n> that pretends to do NUMA without
  actually making the OS calls, which is useful for testing the code
  on non-NUMA systems.
* TODO: I need to add some unit tests

Reviewers: erikd, austin, rwbarton, ezyang, bgamari, hvr, niteria

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2199

1 files changed, 5 insertions, 1 deletions

diff --git a/testsuite/config/ghc b/testsuite/config/ghc
index 355535153c..678cc56bc5 100644
--- a/testsuite/config/ghc
+++ b/testsuite/config/ghc
@@ -26,7 +26,7 @@ config.run_ways           = ['normal', 'hpc']
 config.other_ways         = ['prof', 'normal_h',
                              'prof_hc_hb','prof_hb',
                              'prof_hd','prof_hy','prof_hr',
-                             'threaded1_ls', 'threaded2_hT',
+                             'threaded1_ls', 'threaded2_hT', 'debug_numa',
                              'llvm', 'debugllvm',
                              'profllvm', 'profoptllvm', 'profthreadedllvm',
                              'debug',
@@ -87,6 +87,8 @@ config.way_flags = lambda name : {
     'normal'       : [],
     'normal_h'     : [],
     'g1'           : [],
+    'nursery_chunks' : [],
+    'debug_numa'   : ['-threaded', '-debug'],
     'optasm'       : ['-O', '-fasm'],
     'llvm'         : ['-fllvm'],
     'optllvm'      : ['-O', '-fllvm'],
@@ -119,6 +121,8 @@ config.way_rts_flags = {
     'normal'       : [],
     'normal_h'     : ['-h'], # works without -prof
     'g1'           : ['-G1'],
+    'nursery_chunks' : ['-n32k'],
+    'debug_numa'   : ['-N2', '--debug-numa=2'],
     'optasm'       : [],
     'llvm'         : [],
     'optllvm'      : [],