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Update multichase implementation #51

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Merged
seranian merged 1 commit into from
Apr 10, 2026
Merged

Update multichase implementation #51

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2 changes: 1 addition & 1 deletion multichase.c
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Original file line number Diff line number Diff line change
Expand Up @@ -802,7 +802,7 @@ int main(int argc, char **argv) {
genchase_args.tlb_locality = genchase_args.total_memory;
} else {
genchase_args.total_memory -=
genchase_args.total_memory % genchase_args.tlb_locality;
genchase_args.total_memory % genchase_args.stride;
}

genchase_args.nr_mixer_indices =
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32 changes: 25 additions & 7 deletions permutation.c
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Original file line number Diff line number Diff line change
Expand Up @@ -137,7 +137,7 @@ void generate_chase_mixer(struct generate_chase_common_args *args,
args->mixer = r;
}

// Generate a pointer chasing sequence according to chase args.
// Generate a pointer chasing sequence according to chase args.
void *generate_chase(const struct generate_chase_common_args *args,
size_t mixer_idx) {
char *arena = args->arena;
Expand All @@ -148,9 +148,11 @@ void *generate_chase(const struct generate_chase_common_args *args,
const perm_t *mixer = args->mixer + mixer_idx * args->nr_mixers;
size_t nr_mixer_indices = args->nr_mixer_indices;

size_t nr_tlb_groups = total_memory / tlb_locality;
size_t nr_elts_per_tlb = tlb_locality / stride;
size_t nr_elts = total_memory / stride;
// Set TLB groups in this way to handle where tlb locality is not a multiple
// of stride
size_t nr_tlb_groups = (nr_elts + nr_elts_per_tlb - 1) / nr_elts_per_tlb;
perm_t *tlb_perm;
perm_t *perm;
size_t i;
Expand All @@ -163,9 +165,17 @@ void *generate_chase(const struct generate_chase_common_args *args,
tlb_perm = malloc(nr_tlb_groups * sizeof(*tlb_perm));
gen_permutation(tlb_perm, nr_tlb_groups, 0);
perm = malloc(nr_elts * sizeof(*perm));
size_t perm_idx = 0;
for (i = 0; i < nr_tlb_groups; ++i) {
gen_permutation(&perm[i * nr_elts_per_tlb], nr_elts_per_tlb,
tlb_perm[i] * nr_elts_per_tlb);
size_t group_start = tlb_perm[i] * nr_elts_per_tlb;
size_t nr_elts_in_group = nr_elts_per_tlb;
if (group_start + nr_elts_in_group > nr_elts) {
// Handles a potentially short tlb group in the last iteration.
assert(nr_elts > group_start);
nr_elts_in_group = nr_elts - group_start;
}
gen_permutation(&perm[perm_idx], nr_elts_in_group, group_start);
perm_idx += nr_elts_in_group;
}
free(tlb_perm);

Expand Down Expand Up @@ -211,9 +221,9 @@ void *generate_chase_long(const struct generate_chase_common_args *args,
size_t nr_iteration = nr_mixer_indices / total_par;
const perm_t *mixer = args->mixer + mixer_idx * nr_iteration * args->nr_mixers;

size_t nr_tlb_groups = total_memory / tlb_locality;
size_t nr_elts_per_tlb = tlb_locality / stride;
size_t nr_elts = total_memory / stride;
size_t nr_tlb_groups = (nr_elts + nr_elts_per_tlb - 1) / nr_elts_per_tlb;
perm_t *tlb_perm;
perm_t *perm;
size_t i;
Expand Down Expand Up @@ -246,9 +256,17 @@ void *generate_chase_long(const struct generate_chase_common_args *args,

gen_permutation(tlb_perm, nr_tlb_groups, 0);

size_t perm_idx = j * nr_elts;
for (i = 0; i < nr_tlb_groups; ++i) {
gen_permutation(&perm[j * nr_elts + i * nr_elts_per_tlb], nr_elts_per_tlb,
base + tlb_perm[i] * nr_elts_per_tlb);
size_t group_start = base + tlb_perm[i] * nr_elts_per_tlb;
size_t nr_elts_in_group = nr_elts_per_tlb;
if (tlb_perm[i] * nr_elts_per_tlb + nr_elts_in_group > nr_elts) {
// Handles a potentially short tlb group in the last iteration.
assert(nr_elts > tlb_perm[i] * nr_elts_per_tlb);
nr_elts_in_group = nr_elts - tlb_perm[i] * nr_elts_per_tlb;
}
gen_permutation(&perm[perm_idx], nr_elts_in_group, group_start);
perm_idx += nr_elts_in_group;
}
free(tlb_perm);

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