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HPA: Use dirtiest-first purging.

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This seems to be practically beneficial, despite some pathological corner cases.
This commit is contained in:
David Goldblatt
2021-02-08 14:11:37 -08:00
committed by David Goldblatt
parent 0f6c420f83
commit 73ca4b8ef8
6 changed files with 179 additions and 137 deletions
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86
test/unit/psset.c
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@@ -540,6 +540,89 @@ TEST_BEGIN(test_insert_remove) {
}
TEST_END
TEST_BEGIN(test_purge_prefers_nonhuge) {
/*
* All else being equal, we should prefer purging non-huge pages over
* huge ones.
*/
/* Nothing magic about this constant. */
enum {
NHP = 23,
};
hpdata_t *hpdata;
psset_t psset;
psset_init(&psset);
hpdata_t hpdata_huge[NHP];
uintptr_t huge_begin = (uintptr_t)&hpdata_huge[0];
uintptr_t huge_end = (uintptr_t)&hpdata_huge[NHP];
hpdata_t hpdata_nonhuge[NHP];
uintptr_t nonhuge_begin = (uintptr_t)&hpdata_nonhuge[0];
uintptr_t nonhuge_end = (uintptr_t)&hpdata_nonhuge[NHP];
for (size_t i = 0; i < NHP; i++) {
hpdata_init(&hpdata_huge[i], (void *)((10 + i) * HUGEPAGE),
123 + i);
psset_insert(&psset, &hpdata_huge[i]);
hpdata_init(&hpdata_nonhuge[i],
(void *)((10 + NHP + i) * HUGEPAGE),
456 + i);
psset_insert(&psset, &hpdata_nonhuge[i]);
}
for (int i = 0; i < 2 * NHP; i++) {
hpdata = psset_pick_alloc(&psset, HUGEPAGE * 3 / 4);
psset_update_begin(&psset, hpdata);
void *ptr;
ptr = hpdata_reserve_alloc(hpdata, HUGEPAGE * 3 / 4);
/* Ignore the first alloc, which will stick around. */
(void)ptr;
/*
* The second alloc is to dirty the pages; free it immediately
* after allocating.
*/
ptr = hpdata_reserve_alloc(hpdata, HUGEPAGE / 4);
hpdata_unreserve(hpdata, ptr, HUGEPAGE / 4);
if (huge_begin <= (uintptr_t)hpdata
&& (uintptr_t)hpdata < huge_end) {
hpdata_hugify(hpdata);
}
hpdata_purge_allowed_set(hpdata, true);
psset_update_end(&psset, hpdata);
}
/*
* We've got a bunch of 1/8th dirty hpdatas. It should give us all the
* non-huge ones to purge, then all the huge ones, then refuse to purge
* further.
*/
for (int i = 0; i < NHP; i++) {
hpdata = psset_pick_purge(&psset);
assert_true(nonhuge_begin <= (uintptr_t)hpdata
&& (uintptr_t)hpdata < nonhuge_end, "");
psset_update_begin(&psset, hpdata);
test_psset_fake_purge(hpdata);
hpdata_purge_allowed_set(hpdata, false);
psset_update_end(&psset, hpdata);
}
for (int i = 0; i < NHP; i++) {
hpdata = psset_pick_purge(&psset);
expect_true(huge_begin <= (uintptr_t)hpdata
&& (uintptr_t)hpdata < huge_end, "");
psset_update_begin(&psset, hpdata);
hpdata_dehugify(hpdata);
test_psset_fake_purge(hpdata);
hpdata_purge_allowed_set(hpdata, false);
psset_update_end(&psset, hpdata);
}
}
TEST_END
int
main(void) {
return test_no_reentrancy(
@@ -550,5 +633,6 @@ main(void) {
test_multi_pageslab,
test_stats,
test_oldest_fit,
test_insert_remove);
test_insert_remove,
test_purge_prefers_nonhuge);
}