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SubjectRe: [PATCH 2/2 v2] perf bench futex: add NUMA support
On Mon, 17 Oct 2016, Sebastian Andrzej Siewior wrote:

>+#ifdef HAVE_LIBNUMA_SUPPORT
>+#include <numa.h>
>+#endif

In futex.h

>+static int numa_node = -1;

In futex.h (perhaps rename to futexbench_numa_node?)

>+#ifndef HAVE_LIBNUMA_SUPPORT
>+static int numa_run_on_node(int node __maybe_unused) { return 0; }
>+static int numa_node_of_cpu(int node __maybe_unused) { return 0; }
>+static void *numa_alloc_local(size_t size) { return malloc(size); }
>+static void numa_free(void *p, size_t size __maybe_unused) { return free(p); }
>+#endif
>+
>+static bool cpu_is_local(int cpu)
>+{
>+ if (numa_node < 0)
>+ return true;
>+ if (numa_node_of_cpu(cpu) == numa_node)
>+ return true;
>+ return false;
>+}

In futex.h

>- if (!nthreads) /* default to the number of CPUs */
>- nthreads = ncpus;
>+ if (!nthreads) {
>+ /* default to the number of CPUs per NUMA node */

This comment should go...

>+ if (numa_node < 0) {
>+ nthreads = ncpus;
>+ } else {

here.

>+ for (i = 0; i < ncpus; i++) {
>+ if (cpu_is_local(i))
>+ nthreads++;
>+ }
>+ if (!nthreads)
>+ err(EXIT_FAILURE, "No online CPUs for this node");
>+ }
>+ } else {
>+ int cpu_available = 0;
>
>- worker = calloc(nthreads, sizeof(*worker));
>+ for (i = 0; i < ncpus && !cpu_available; i++) {
>+ if (cpu_is_local(i))
>+ cpu_available = 1;
>+ }

Is this really necessary? If the user passes the number of threads, then we shouldn't
care about ncpus; we just run all the threads on the specified node. Wouldn't the
below numa_run_on_node() ensure that the node is not, for example, CPU-less?

>+ if (!cpu_available)
>+ err(EXIT_FAILURE, "No online CPUs for this node");
>+ }
>+
>+ if (numa_node >= 0) {
>+ ret = numa_run_on_node(numa_node);
>+ if (ret < 0)
>+ err(EXIT_FAILURE, "numa_run_on_node");


Thanks,
Davidlohr

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