[tor-commits] [tor/master] Prefer 32-bit implementation for timing wheels on 32-bit systems.

[nickm at torproject.org]

commit e0809ec5f5de4c3d22527425bf6253843044e1b2
Author: Nick Mathewson <nickm at torproject.org>
Date:   Mon Apr 9 15:21:10 2018 -0400

    Prefer 32-bit implementation for timing wheels on 32-bit systems.
    
    This might make our timing-wheel code a tiny bit faster there.
    
    Closes ticket 24688.
---
 changes/bug24688    | 3 +++
 src/common/timers.c | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/changes/bug24688 b/changes/bug24688
new file mode 100644
index 000000000..c376fe6a0
--- /dev/null
+++ b/changes/bug24688
@@ -0,0 +1,3 @@
+  o Minor features (performance, 32-bit):
+    - Make our timing-wheel code run a tiny bit faster on 32-bit platforms,
+      by preferring 32-bit math to 64-bit. Closes ticket 24688.
diff --git a/src/common/timers.c b/src/common/timers.c
index a90817da1..6f6236ed3 100644
--- a/src/common/timers.c
+++ b/src/common/timers.c
@@ -64,6 +64,11 @@ struct timeout_cb {
  * above TIMEOUT_MAX can also be super-inefficient. Choosing 5 here sets
  * timeout_max to 2^30 ticks, or 29 hours with our value for USEC_PER_TICK */
 #define WHEEL_NUM 5
+#if SIZEOF_VOID_P == 4
+/* On 32-bit platforms, we want to override wheel_bit, so that timeout.c will
+ * use 32-bit math. */
+#define WHEEL_BIT 5
+#endif
 #include "src/ext/timeouts/timeout.c"
 
 static struct timeouts *global_timeouts = NULL;