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, 7 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index d7eb7380cd..070bae54d9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1103,6 +1103,13 @@ if test $UseLibdw = "YES" ; then
 fi
 AC_DEFINE_UNQUOTED([USE_LIBDW], [$USE_LIBDW], [Set to 1 to use libdw])
 
+dnl ** Have libnuma?
+dnl --------------------------------------------------------------
+AC_CHECK_HEADERS([numa.h numaif.h])
+AC_CHECK_LIB(numa, numa_available,
+        [AC_DEFINE([HAVE_LIBNUMA], [1], [Define to 1 if you have libnuma.])]
+        [])
+
 dnl ** Documentation
 dnl --------------------------------------------------------------
 if test -n "$SPHINXBUILD"; then