From e0a9cb25b0af87723d50cb8d8cffa10f1ebf7dcc Mon Sep 17 00:00:00 2001 From: "Wladimir J. van der Laan" Date: Tue, 22 Nov 2016 09:59:50 +0100 Subject: bench: Fix subtle counting issue when rescaling iteration count Make sure that the count is a zero modulo the new mask before scaling, otherwise the next time until a measure triggers will take only 1/2 as long as accounted for. This caused the 'min time' to be potentially off by as much as 100%. --- src/bench/bench.cpp | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'src/bench/bench.cpp') diff --git a/src/bench/bench.cpp b/src/bench/bench.cpp index 227546a7a7..8942da8c74 100644 --- a/src/bench/bench.cpp +++ b/src/bench/bench.cpp @@ -64,8 +64,11 @@ bool State::KeepRunning() return true; } if (elapsed*16 < maxElapsed) { - countMask = ((countMask<<1)|1) & ((1LL<<60)-1); - countMaskInv = 1./(countMask+1); + uint64_t newCountMask = ((countMask<<1)|1) & ((1LL<<60)-1); + if ((count & newCountMask)==0) { + countMask = newCountMask; + countMaskInv = 1./(countMask+1); + } } } lastTime = now; -- cgit v1.2.3