Improve time estimates, taking into account the number of cores.

This only affects time estimates while keysafe is generating hashes;
it does not affect cost estimates to brute-force.

1 files changed, 4 insertions, 15 deletions

diff --git a/ExpensiveHash.hs b/ExpensiveHash.hs
index 8c473d3..ff9c51c 100644
--- a/ExpensiveHash.hs
+++ b/ExpensiveHash.hs
@@ -50,7 +50,8 @@ expensiveHash (UseArgon2 cost opts) (Salt s) b = ExpensiveHash cost $
 
 benchmarkExpensiveHash :: Int -> ExpensiveHashTunable -> Cost op -> IO (BenchmarkResult (Cost op))
 benchmarkExpensiveHash rounds tunables@(UseArgon2 _ hashopts) expected = do
-	numcores <- fromIntegral <$> getNumCores
+	numcores <- fromIntegral . fromMaybe (error "Unknown number of physical cores.") 
+		<$> getNumCores
 	start <- getCurrentTime
 	forM_ [1..rounds] $ \_ -> do
 		let ExpensiveHash _ t = expensiveHash tunables
@@ -59,11 +60,11 @@ benchmarkExpensiveHash rounds tunables@(UseArgon2 _ hashopts) expected = do
 		t `deepseq` return ()
 	end <- getCurrentTime
 	let diff = floor $ end `diffUTCTime` start
-	let actual = CPUCost $ Seconds diff
+	let maxthreads = Argon2.hashParallelism hashopts
+	let actual = CPUCost (Seconds diff) (Divisibility $ fromIntegral maxthreads)
 	-- The expected cost is for a single core, so adjust it
 	-- based on the number of cores, up to a maximum of the number
 	-- of threads that the hash is configred to use.
-	let maxthreads = Argon2.hashParallelism hashopts
 	let usedcores = min maxthreads numcores
 	let adjustedexpected = mapCost (`div` fromIntegral usedcores) expected
 	return $ BenchmarkResult
@@ -71,18 +72,6 @@ benchmarkExpensiveHash rounds tunables@(UseArgon2 _ hashopts) expected = do
 		, actualBenchmark = actual
 		}
 
--- Number of physical cores. This is not the same as
--- getNumProcessors, which includes hyper-threading.
-getNumCores :: IO Integer
-getNumCores = getmax . mapMaybe parse . lines <$> readFile "/proc/cpuinfo"
-  where
-	getmax [] = error "Unknown number of physical cores."
-	getmax l = maximum l + 1 -- add 1 because /proc/cpuinfo counts from 0
-	parse l
-		| "core id" `isPrefixOf` l =
-			readMaybe $ drop 1 $ dropWhile (/= ':') l
-		| otherwise = Nothing
-
 benchmarkTunables :: Tunables -> IO ()
 benchmarkTunables tunables = do
 	putStrLn "/proc/cpuinfo:"