c13a8ee402
The ray tracer is float-compute-bound (devirt, alloc removal, type-proving all measured flat on it), so it can't validate the optimization passes. Add a small cross-language suite (AWFY + CLBG style, portable Clojure) isolating the axes it misses: binary-trees allocation / GC pressure (escaping short-lived records) dispatch megamorphic protocol dispatch (~1M dispatches/s; WP can't devirt) collections persistent map/vector churn bench/run.sh runs them; bench/README.md maps each to the pass it exercises. collections immediately surfaced jolt-684u: the persistent hash map is O(n) per assoc (flat copy-on-write bucket array, not a HAMT) — n=4000 assocs take 50s. Invisible to the ray tracer (no maps). Co-authored-by: Yogthos <yogthos@gmail.com>
46 lines
1.8 KiB
Clojure
46 lines
1.8 KiB
Clojure
;; collections — PERSISTENT-COLLECTION churn. Builds and reads persistent maps
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;; and vectors (32-way hash/array tries) under heavy assoc/update/conj/lookup, a
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;; word-count-style workload (cf. CLBG k-nucleotide). Exercises jolt's persistent
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;; data structures and (eventually) transients — an axis the ray tracer (fixed
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;; records, no collections in the hot loop) doesn't touch.
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;;
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;; Portable Clojure (jolt + JVM Clojure).
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;; jolt -m collections 200000 (JOLT_DIRECT_LINK=1 JOLT_WHOLE_PROGRAM=1)
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(ns collections)
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;; map churn: accumulate a frequency map over a stream of keys, then sum it back
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(defn freq-map [n buckets]
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(loop [i 0 m {}]
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(if (< i n)
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(recur (inc i)
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(let [k (mod (* i 2654435761) buckets)]
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(assoc m k (+ 1 (get m k 0)))))
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m)))
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(defn sum-vals [m]
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(reduce (fn [acc k] (+ acc (get m k))) 0 (keys m)))
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;; vector churn: conj many, then reduce
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(defn vec-sum [n]
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(let [v (loop [i 0 v []] (if (< i n) (recur (inc i) (conj v (mod i 1000))) v))]
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(reduce + 0 v)))
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(defn run [n]
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(let [m (freq-map n 4096)]
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(+ (sum-vals m) (vec-sum (quot n 4)))))
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(defn -main [& args]
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(let [n (if (seq args) (Integer/parseInt (first args)) 200000)]
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(dotimes [_ 2] (run (quot n 4))) ; warmup
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(let [runs 3
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times (mapv (fn [_]
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(let [t0 (System/nanoTime)
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r (run n)
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ms (/ (- (System/nanoTime) t0) 1000000.0)]
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[ms r]))
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(range runs))
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mss (mapv first times)
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mean (/ (reduce + mss) runs)]
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(println "collections n" n "result" (second (first times)))
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(println "runs:" (mapv (fn [t] (/ (Math/round (* t 10.0)) 10.0)) mss))
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(println "mean:" (/ (Math/round (* mean 10.0)) 10.0) "ms"))))
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