#!/usr/bin/env python3
#
# Computes difference between measurements produced by ./benchmark.py.
#

import argparse
import json

import numpy as np


if not torch._six.PY3:
    raise RuntimeError("DDP benchmark requires Python 3")


def load(path):
    with open(path, 'r') as f:
        return json.load(f)


def main():
    parser = argparse.ArgumentParser(description='PyTorch distributed benchmark diff')
    parser.add_argument("file", nargs=2)
    args = parser.parse_args()

    if len(args.file) != 2:
        raise RuntimeError("Must specify 2 files to diff")

    ja = load(args.file[0])
    jb = load(args.file[1])

    keys = (set(ja.keys()) | set(jb.keys())) - set(["benchmark_results"])
    print("{:20s} {:>20s}      {:>20s}".format("", "baseline", "test"))
    print("{:20s} {:>20s}      {:>20s}".format("", "-" * 20, "-" * 20))
    for key in sorted(keys):
        va = str(ja.get(key, "-"))
        vb = str(jb.get(key, "-"))
        print("{:20s} {:>20s}  vs  {:>20s}".format(key + ":", va, vb))
    print("")

    ba = ja["benchmark_results"]
    bb = jb["benchmark_results"]
    for ra, rb in zip(ba, bb):
        if ra["model"] != rb["model"]:
            continue
        if ra["batch_size"] != rb["batch_size"]:
            continue

        model = ra["model"]
        batch_size = int(ra["batch_size"])
        name = "{} with batch size {}".format(model, batch_size)
        print("Benchmark: {}".format(name))

        # Print header
        print("")
        print("{:>10s}".format(""), end='')  # noqa: E999
        for _ in [75, 95]:
            print("{:>16s}{:>10s}{:>10s}".format("sec/iter", "ex/sec", "diff"), end='')  # noqa: E999
        print("")

        # Print measurements
        for (i, (xa, xb)) in enumerate(zip(ra["result"], rb["result"])):
            # Ignore round without ddp
            if i == 0:
                continue
            # Sanity check: ignore if number of ranks is not equal
            if len(xa["ranks"]) != len(xb["ranks"]):
                continue

            ngpus = len(xa["ranks"])
            ma = sorted(xa["measurements"])
            mb = sorted(xb["measurements"])
            print("{:>4d} GPUs:".format(ngpus), end='')  # noqa: E999
            for p in [75, 95]:
                va = np.percentile(ma, p)
                vb = np.percentile(mb, p)
                # We're measuring time, so lower is better (hence the negation)
                delta = -100 * ((vb - va) / va)
                print("  p{:02d}: {:8.3f}s {:7d}/s {:+8.1f}%".format(p, vb, int(batch_size / vb), delta), end='')  # noqa: E999
            print("")
        print("")


if __name__ == '__main__':
    main()