git: c15085278cb5 - main - arm64 pmap: implement per-superpage locks
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Date: Thu, 17 Nov 2022 17:12:51 UTC
The branch main has been updated by andrew:
URL: https://cgit.FreeBSD.org/src/commit/?id=c15085278cb55bd3c1ea252adf5635bb6800b431
commit c15085278cb55bd3c1ea252adf5635bb6800b431
Author: Andrew Turner <andrew@FreeBSD.org>
AuthorDate: 2022-08-19 13:54:36 +0000
Commit: Andrew Turner <andrew@FreeBSD.org>
CommitDate: 2022-11-17 17:12:40 +0000
arm64 pmap: implement per-superpage locks
As with amd64 pmap introduce per-superpage locks backed by pages
allocated by their respective domains.
This significiantly reduces lock contantion from pmap when running
poudriere on a 160 core Ampere Altra server
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D36310
---
sys/arm64/arm64/pmap.c | 209 +++++++++++++++++++++++++++++++++----------------
1 file changed, 141 insertions(+), 68 deletions(-)
diff --git a/sys/arm64/arm64/pmap.c b/sys/arm64/arm64/pmap.c
index 4e101ace8356..7df16bc41922 100644
--- a/sys/arm64/arm64/pmap.c
+++ b/sys/arm64/arm64/pmap.c
@@ -188,8 +188,15 @@ __FBSDID("$FreeBSD$");
#define pmap_l1_pindex(v) (NUL2E + ((v) >> L1_SHIFT))
#define pmap_l2_pindex(v) ((v) >> L2_SHIFT)
-static struct md_page *
-pa_to_pvh(vm_paddr_t pa)
+struct pmap_large_md_page {
+ struct rwlock pv_lock;
+ struct md_page pv_page;
+ /* Pad to a power of 2, see pmap_init_pv_table(). */
+ int pv_pad[2];
+};
+
+static struct pmap_large_md_page *
+_pa_to_pmdp(vm_paddr_t pa)
{
struct vm_phys_seg *seg;
int segind;
@@ -197,26 +204,46 @@ pa_to_pvh(vm_paddr_t pa)
for (segind = 0; segind < vm_phys_nsegs; segind++) {
seg = &vm_phys_segs[segind];
if (pa >= seg->start && pa < seg->end)
- return ((struct md_page *)seg->md_first +
+ return ((struct pmap_large_md_page *)seg->md_first +
pmap_l2_pindex(pa) - pmap_l2_pindex(seg->start));
}
- panic("pa 0x%jx not within vm_phys_segs", (uintmax_t)pa);
+ return (NULL);
+}
+
+static struct pmap_large_md_page *
+pa_to_pmdp(vm_paddr_t pa)
+{
+ struct pmap_large_md_page *pvd;
+
+ pvd = _pa_to_pmdp(pa);
+ if (pvd == NULL)
+ panic("pa 0x%jx not within vm_phys_segs", (uintmax_t)pa);
+ return (pvd);
}
-static struct md_page *
-page_to_pvh(vm_page_t m)
+static struct pmap_large_md_page *
+page_to_pmdp(vm_page_t m)
{
struct vm_phys_seg *seg;
seg = &vm_phys_segs[m->segind];
- return ((struct md_page *)seg->md_first +
+ return ((struct pmap_large_md_page *)seg->md_first +
pmap_l2_pindex(VM_PAGE_TO_PHYS(m)) - pmap_l2_pindex(seg->start));
}
-#define NPV_LIST_LOCKS MAXCPU
+#define pa_to_pvh(pa) (&(pa_to_pmdp(pa)->pv_page))
+#define page_to_pvh(m) (&(page_to_pmdp(m)->pv_page))
-#define PHYS_TO_PV_LIST_LOCK(pa) \
- (&pv_list_locks[pa_index(pa) % NPV_LIST_LOCKS])
+#define PHYS_TO_PV_LIST_LOCK(pa) ({ \
+ struct pmap_large_md_page *_pvd; \
+ struct rwlock *_lock; \
+ _pvd = _pa_to_pmdp(pa); \
+ if (__predict_false(_pvd == NULL)) \
+ _lock = &pv_dummy_large.pv_lock; \
+ else \
+ _lock = &(_pvd->pv_lock); \
+ _lock; \
+})
#define CHANGE_PV_LIST_LOCK_TO_PHYS(lockp, pa) do { \
struct rwlock **_lockp = (lockp); \
@@ -304,9 +331,10 @@ struct pv_chunks_list {
struct pv_chunks_list __exclusive_cache_line pv_chunks[PMAP_MEMDOM];
-static struct rwlock pv_list_locks[NPV_LIST_LOCKS];
-static struct md_page *pv_table;
-static struct md_page pv_dummy;
+__exclusive_cache_line static struct pmap_large_md_page pv_dummy_large;
+#define pv_dummy pv_dummy_large.pv_page
+__read_mostly static struct pmap_large_md_page *pv_table;
+__read_mostly vm_paddr_t pmap_last_pa;
vm_paddr_t dmap_phys_base; /* The start of the dmap region */
vm_paddr_t dmap_phys_max; /* The limit of the dmap region */
@@ -1311,6 +1339,104 @@ pmap_init_asids(struct asid_set *set, int bits)
mtx_init(&set->asid_set_mutex, "asid set", NULL, MTX_SPIN);
}
+static void
+pmap_init_pv_table(void)
+{
+ struct vm_phys_seg *seg, *next_seg;
+ struct pmap_large_md_page *pvd;
+ vm_size_t s;
+ long start, end, highest, pv_npg;
+ int domain, i, j, pages;
+
+ /*
+ * We strongly depend on the size being a power of two, so the assert
+ * is overzealous. However, should the struct be resized to a
+ * different power of two, the code below needs to be revisited.
+ */
+ CTASSERT((sizeof(*pvd) == 64));
+
+ /*
+ * Calculate the size of the array.
+ */
+ pv_npg = 0;
+ for (i = 0; i < vm_phys_nsegs; i++) {
+ seg = &vm_phys_segs[i];
+ pv_npg += pmap_l2_pindex(roundup2(seg->end, L2_SIZE)) -
+ pmap_l2_pindex(seg->start);
+ }
+ s = (vm_size_t)pv_npg * sizeof(struct pmap_large_md_page);
+ s = round_page(s);
+ pv_table = (struct pmap_large_md_page *)kva_alloc(s);
+ if (pv_table == NULL)
+ panic("%s: kva_alloc failed\n", __func__);
+
+ /*
+ * Iterate physical segments to allocate domain-local memory for PV
+ * list headers.
+ */
+ highest = -1;
+ s = 0;
+ for (i = 0; i < vm_phys_nsegs; i++) {
+ seg = &vm_phys_segs[i];
+ start = highest + 1;
+ end = start + pmap_l2_pindex(roundup2(seg->end, L2_SIZE)) -
+ pmap_l2_pindex(seg->start);
+ domain = seg->domain;
+
+ if (highest >= end)
+ continue;
+
+ pvd = &pv_table[start];
+
+ pages = end - start + 1;
+ s = round_page(pages * sizeof(*pvd));
+ highest = start + (s / sizeof(*pvd)) - 1;
+
+ for (j = 0; j < s; j += PAGE_SIZE) {
+ vm_page_t m = vm_page_alloc_noobj_domain(domain,
+ VM_ALLOC_ZERO);
+ if (m == NULL)
+ panic("failed to allocate PV table page");
+ pmap_qenter((vm_offset_t)pvd + j, &m, 1);
+ }
+
+ for (j = 0; j < s / sizeof(*pvd); j++) {
+ rw_init_flags(&pvd->pv_lock, "pmap pv list", RW_NEW);
+ TAILQ_INIT(&pvd->pv_page.pv_list);
+ pvd++;
+ }
+ }
+ pvd = &pv_dummy_large;
+ memset(pvd, 0, sizeof(*pvd));
+ rw_init_flags(&pvd->pv_lock, "pmap pv list dummy", RW_NEW);
+ TAILQ_INIT(&pvd->pv_page.pv_list);
+
+ /*
+ * Set pointers from vm_phys_segs to pv_table.
+ */
+ for (i = 0, pvd = pv_table; i < vm_phys_nsegs; i++) {
+ seg = &vm_phys_segs[i];
+ seg->md_first = pvd;
+ pvd += pmap_l2_pindex(roundup2(seg->end, L2_SIZE)) -
+ pmap_l2_pindex(seg->start);
+
+ /*
+ * If there is a following segment, and the final
+ * superpage of this segment and the initial superpage
+ * of the next segment are the same then adjust the
+ * pv_table entry for that next segment down by one so
+ * that the pv_table entries will be shared.
+ */
+ if (i + 1 < vm_phys_nsegs) {
+ next_seg = &vm_phys_segs[i + 1];
+ if (pmap_l2_pindex(roundup2(seg->end, L2_SIZE)) - 1 ==
+ pmap_l2_pindex(next_seg->start)) {
+ pvd--;
+ }
+ }
+ }
+}
+
/*
* Initialize the pmap module.
* Called by vm_init, to initialize any structures that the pmap
@@ -1319,11 +1445,8 @@ pmap_init_asids(struct asid_set *set, int bits)
void
pmap_init(void)
{
- struct vm_phys_seg *seg, *next_seg;
- struct md_page *pvh;
- vm_size_t s;
uint64_t mmfr1;
- int i, pv_npg, vmid_bits;
+ int i, vmid_bits;
/*
* Are large page mappings enabled?
@@ -1364,57 +1487,7 @@ pmap_init(void)
MTX_DEF);
TAILQ_INIT(&pv_chunks[i].pvc_list);
}
-
- /*
- * Initialize the pool of pv list locks.
- */
- for (i = 0; i < NPV_LIST_LOCKS; i++)
- rw_init(&pv_list_locks[i], "pmap pv list");
-
- /*
- * Calculate the size of the pv head table for superpages.
- */
- pv_npg = 0;
- for (i = 0; i < vm_phys_nsegs; i++) {
- seg = &vm_phys_segs[i];
- pv_npg += pmap_l2_pindex(roundup2(seg->end, L2_SIZE)) -
- pmap_l2_pindex(seg->start);
- }
-
- /*
- * Allocate memory for the pv head table for superpages.
- */
- s = (vm_size_t)(pv_npg * sizeof(struct md_page));
- s = round_page(s);
- pv_table = kmem_malloc(s, M_WAITOK | M_ZERO);
- for (i = 0; i < pv_npg; i++)
- TAILQ_INIT(&pv_table[i].pv_list);
- TAILQ_INIT(&pv_dummy.pv_list);
-
- /*
- * Set pointers from vm_phys_segs to pv_table.
- */
- for (i = 0, pvh = pv_table; i < vm_phys_nsegs; i++) {
- seg = &vm_phys_segs[i];
- seg->md_first = pvh;
- pvh += pmap_l2_pindex(roundup2(seg->end, L2_SIZE)) -
- pmap_l2_pindex(seg->start);
-
- /*
- * If there is a following segment, and the final
- * superpage of this segment and the initial superpage
- * of the next segment are the same then adjust the
- * pv_table entry for that next segment down by one so
- * that the pv_table entries will be shared.
- */
- if (i + 1 < vm_phys_nsegs) {
- next_seg = &vm_phys_segs[i + 1];
- if (pmap_l2_pindex(roundup2(seg->end, L2_SIZE)) - 1 ==
- pmap_l2_pindex(next_seg->start)) {
- pvh--;
- }
- }
- }
+ pmap_init_pv_table();
vm_initialized = 1;
}