Re: [PATCH v3 1/1] memalign: Support scanning for aligned chunks.

[DJ Delorie <dj@redhat.com>]

Sidebar - I ran the malloc benchtests on before/after builds, and the
variation between the two seemed no more or less than the variation
between just running the "before" tests twice.

The variation, just running the same tests multiple times, seems larger
than the gains/losses we typically get with malloc tweaks, though.
Computers are just too fast and unpredictable these days ;-)

I also have a python script that compares malloc benchtest runs (below).
Run like this:

 $ compare-malloc.py ~/tools/upstream/glibc.pristine.build/benchtests ~/tools/upstream/glibc.memalign.build/benchtests `ls -1d bench-malloc-simple-*.out | nsort` > /tmp/malloc2.csv

If there's interest, I can add this to benchtests/scripts

---------- 8< ----------
#!/usr/bin/python

import sys
import json
import argparse
import pprint
    
def do_keys (pattern, bd, ad):
    avg = 0
    count = 0
    print_it = 0;
    for b in sorted(bd.keys()):
        if pattern in b:
            if print_it:
                print ("%s,%s,%s,%s" % (save_b, bv, av, imp));
            save_b = b;
            bv = bd[b]
            av = ad[b]
            imp = av / bv;
            avg += imp
            count = count + 1
            print_it = 1

    if print_it:
        print ("%s,%s,%s,%s,%s" % (save_b, bv, av, imp, avg/count));

def compare_files(fn1, fn2, t):
    b = open (fn1, 'r')
    before = json.load(b)
    a = open (fn2, 'r')
    after = json.load(a)

    print (t)
    print ("Test,Before,After,Ratio,Average")
    do_keys ('max_rss', before['functions']['malloc'][''], after['functions']['malloc'][''])
    do_keys ('main_arena', before['functions']['malloc'][''], after['functions']['malloc'][''])
    do_keys ('thread_arena', before['functions']['malloc'][''], after['functions']['malloc'][''])
    print ("");

def main(argv):
    before_dir = argv[1];
    after_dir = argv[2];
    files = argv[3:]

    for f in files:
        bf = before_dir + "/" + f;
        af = after_dir + "/" + f;
        compare_files (bf, af, f)

if __name__ == '__main__':
    main(sys.argv)