posix: add posix_thread attribute for thread affinity

First use will be to bind the prefault thread to its NUMA node.
rishvin · Jul 6, 2023 · 920a748 · 920a748
1 parent c2baf51
commit 920a748
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diff --git a/include/seastar/core/posix.hh b/include/seastar/core/posix.hh
@@ -44,6 +44,7 @@
 #include <functional>
 #include <memory>
 #include <set>
+#include <optional>
 #endif
 #include "abort_on_ebadf.hh"
 #include <seastar/core/sstring.hh>
@@ -442,8 +443,10 @@ public:
             set(std::forward<Rest>(rest)...);
         }
         void set(stack_size ss) { _stack_size = ss; }
+        void set(cpu_set_t affinity) { _affinity = affinity; }
     private:
         stack_size _stack_size;
+        std::optional<cpu_set_t> _affinity;
         friend class posix_thread;
     };
 };

diff --git a/src/core/posix.cc b/src/core/posix.cc
@@ -122,6 +122,11 @@ posix_thread::posix_thread(attr a, std::function<void ()> func)
     }
 #endif
 
+    if (a._affinity) {
+        auto& cpuset = *a._affinity;
+        pthread_attr_setaffinity_np(&pa, sizeof(cpuset), &cpuset);
+    }
+
     r = pthread_create(&_pthread, &pa,
                 &posix_thread::start_routine, _func.get());
     if (r) {