Messages in this thread | | | From | Denys Vlasenko <> | Subject | Re: [PATCH 3/3] lib: vsprintf: added a put_dec() test and benchmark tool | Date | Fri, 6 Aug 2010 07:10:06 +0200 |
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On Friday 06 August 2010 00:38, Michal Nazarewicz wrote: > This commit adds a test application for the put_dec() and > family of functions that are used by the previous two commits. > > Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
> +put-dec-test: put-dec-test.c > + exec $(CC) $(CFLAGS) -o $@ $<
(1) Why exec? (2) Add -Wall, you'd be surprised
> +static uint64_t rand_64(void) > +{ > + uint64_t v = 0, m = 1; > + for (;;) { > + uint64_t n; > + v = m * rand(); > + n = m + m * RAND_MAX; > + if (n < m) > + break; > + m = n; > + } > + return v; > +}
What this function do? Looks cryptic. In my testing, it picks 0 quite often.
> +static char buf1[24];
Can you size the array safely, without assuming that long long is no wider than 64 bits?
> +#define FUNC(func, outer, inner, correction, format, value) do { \ > + struct timeval start; \ > + unsigned i, o; \ > + for (i = (inner); i--; ) { \ > + typeof(value) v = (value); \ > + ret |= test(#func, func(buf1, v), format, v); \
I'd add memset(buf1, 77, sizeof(buf1)) before test
> +int main(int argc, char **argv) { > + unsigned long iterations = 1000, i; > + struct timeval correction; > + int ret = 0; > + > + srand(time(NULL)); > + > + if (argc > 1) > + iterations = atoi(argv[1]); > + > + gettimeofday(&correction, NULL); > + for (i = 25000 * iterations; i; --i) > + rand_64(); > + stop(NULL, &correction, NULL);
Why is this "correction" thing needed? I looked at the entire machinery and I see no reason to have it.
> + puts(">> Benchmarks:\n\tput_dec_full()"); > + fflush(NULL); > + > + FUNC(orig_put_dec_full, iterations, 100000, NULL, "%05u", i);
You have variable named i, you pass it as macro parameter, but macro has local variable named i too. Is it an International Obfuscated C Code Contest entry?
> + FUNC(mod1_put_dec_full, iterations, 100000, NULL, "%05u", i); > + FUNC(mod3_put_dec_full, iterations, 100000, NULL, "%05u", i); > + FUNC(mod5_put_dec_full, iterations * 10, 10000, NULL, "%04u", i);
> + puts("\tput_dec_trunc()"); > + fflush(NULL); > + > + FUNC(orig_put_dec_trunc, iterations, 100000, NULL, "%u", i); > + FUNC(mod1_put_dec_trunc, iterations, 100000, NULL, "%u", i); > + FUNC(mod3_put_dec_trunc, iterations, 100000, NULL, "%u", i); > + FUNC(mod5_put_dec_trunc, iterations * 10, 10000, NULL, "%u", i); > + FUNC(mod3_put_dec_8bit, iterations * 500, 256, NULL, "%u", i);
> + puts("\n\tput_dec()"); > + fflush(NULL); > + > + FUNC(orig_put_dec, iterations / 4, 100000, &correction, "%llu", rand_64());
"%llu" fmt is for unsigned long long, not uint64_t.
> + FUNC(mod1_put_dec, iterations / 4, 100000, &correction, "%llu", rand_64()); > + FUNC(mod2_put_dec, iterations / 4, 100000, &correction, "%llu", rand_64()); > + FUNC(mod3_put_dec, iterations / 4, 100000, &correction, "%llu", rand_64()); > + FUNC(mod4_put_dec, iterations / 4, 100000, &correction, "%llu", rand_64()); > + FUNC(mod5_put_dec, iterations / 4, 100000, &correction, "%llu", rand_64()); > + FUNC(mod6_put_dec, iterations / 4, 100000, &correction, "%llu", rand_64()); > + FUNC(mod7_put_dec, iterations / 4, 100000, &correction, "%llu", rand_64()); > + FUNC(mod8_put_dec, iterations / 4, 100000, &correction, "%llu", rand_64());
Here a lot of CPU time is taken by rand() calls. Also, you use different values for different functions, which is wrong.
-- vda
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