Andrei Gudkov <gudkov.and...@huawei.com> wrote:
> In sampling mode, a new metric is collected and reported:
> number of pages entirely filled with zeroes.
Good idea.
> @@ -331,11 +336,20 @@ static uint32_t compute_page_hash(void *ptr)
> v2 = QEMU_XXHASH_SEED + XXH_PRIME64_2;
> v3 = QEMU_XXHASH_SEED + 0;
> v4 = QEMU_XXHASH_SEED - XXH_PRIME64_1;
> - for (i = 0; i < TARGET_PAGE_SIZE / 8; i += 4) {
> - v1 = XXH64_round(v1, p[i + 0]);
> - v2 = XXH64_round(v2, p[i + 1]);
> - v3 = XXH64_round(v3, p[i + 2]);
> - v4 = XXH64_round(v4, p[i + 3]);
> + if (ptr) {
It smells like a hack, that is only going to be used once in the
program.
But the only other option that I can think is repeating the function for
the zero case.
No way to win here.
> + for (i = 0; i < TARGET_PAGE_SIZE / 8; i += 4) {
> + v1 = XXH64_round(v1, p[i + 0]);
> + v2 = XXH64_round(v2, p[i + 1]);
> + v3 = XXH64_round(v3, p[i + 2]);
> + v4 = XXH64_round(v4, p[i + 3]);
> + }
> + } else {
> + for (i = 0; i < TARGET_PAGE_SIZE / 8; i += 4) {
> + v1 = XXH64_round(v1, 0);
> + v2 = XXH64_round(v2, 0);
> + v3 = XXH64_round(v3, 0);
> + v4 = XXH64_round(v4, 0);
> + }
> }
> res = XXH64_mergerounds(v1, v2, v3, v4);
> res += TARGET_PAGE_SIZE;
> @@ -343,6 +357,17 @@ static uint32_t compute_page_hash(void *ptr)
> return (uint32_t)(res & UINT32_MAX);
> }
>
> +static uint32_t get_zero_page_hash(void)
> +{
> + static uint32_t hash;
> + static int is_computed;
bool?
Later, Juan.
