The branch main has been updated by bnovkov:
URL:
https://cgit.FreeBSD.org/src/commit/?id=a8693e89e3e4a04efd02901cc93bb6148e3e40d6
commit a8693e89e3e4a04efd02901cc93bb6148e3e40d6
Author: Bojan Novković <bnov...@freebsd.org>
AuthorDate: 2024-07-14 13:14:22 +0000
Commit: Bojan Novković <bnov...@freebsd.org>
CommitDate: 2024-07-30 15:38:24 +0000
vm: Introduce vm_page_alloc_nofree_domain
This patch adds a reservation-aware bump allocator intended for
allocating NOFREE pages. The main goal of this change is to reduce the
long-term fragmentation issues caused by pages that are never freed during
runtime.
The `vm_page_alloc_nofree_domain` routine hands out 0-order pages from
a preallocated superpage. Once an active NOFREE superpage fills up, the
routine will try to allocate a new one and discard the old one.
This routine will get invoked whenever VM_ALLOC_NOFREE is passed to
vm_page_alloc_noobj or vm_page_alloc.
Differential Revision: https://reviews.freebsd.org/D45863
Reviewed by: alc, kib, markj
Tested by: alc
---
sys/vm/vm_page.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++
sys/vm/vm_pagequeue.h | 4 ++++
2 files changed, 66 insertions(+)
diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
index 3b6b88e4eb32..ff9df7f4a9fc 100644
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -163,6 +163,7 @@ SYSCTL_PROC(_vm, OID_AUTO, page_blacklist, CTLTYPE_STRING |
CTLFLAG_RD |
static uma_zone_t fakepg_zone;
static void vm_page_alloc_check(vm_page_t m);
+static vm_page_t vm_page_alloc_nofree_domain(int domain, int req);
static bool _vm_page_busy_sleep(vm_object_t obj, vm_page_t m,
vm_pindex_t pindex, const char *wmesg, int allocflags, bool locked);
static void vm_page_clear_dirty_mask(vm_page_t m, vm_page_bits_t pagebits);
@@ -2099,6 +2100,11 @@ vm_page_alloc_domain_after(vm_object_t object,
vm_pindex_t pindex, int domain,
if (!vm_pager_can_alloc_page(object, pindex))
return (NULL);
again:
+ if (__predict_false((req & VM_ALLOC_NOFREE) != 0)) {
+ m = vm_page_alloc_nofree_domain(domain, req);
+ if (m != NULL)
+ goto found;
+ }
#if VM_NRESERVLEVEL > 0
/*
* Can we allocate the page from a reservation?
@@ -2430,6 +2436,12 @@ vm_page_alloc_noobj_domain(int domain, int req)
((req & VM_ALLOC_NOFREE) != 0 ? PG_NOFREE : 0);
vmd = VM_DOMAIN(domain);
again:
+ if (__predict_false((req & VM_ALLOC_NOFREE) != 0)) {
+ m = vm_page_alloc_nofree_domain(domain, req);
+ if (m != NULL)
+ goto found;
+ }
+
if (vmd->vmd_pgcache[VM_FREEPOOL_DIRECT].zone != NULL) {
m = uma_zalloc(vmd->vmd_pgcache[VM_FREEPOOL_DIRECT].zone,
M_NOWAIT | M_NOVM);
@@ -2480,6 +2492,56 @@ found:
return (m);
}
+#if VM_NRESERVLEVEL > 1
+#define VM_NOFREE_IMPORT_ORDER (VM_LEVEL_1_ORDER + VM_LEVEL_0_ORDER)
+#elif VM_NRESERVLEVEL > 0
+#define VM_NOFREE_IMPORT_ORDER VM_LEVEL_0_ORDER
+#else
+#define VM_NOFREE_IMPORT_ORDER 8
+#endif
+
+/*
+ * Allocate a single NOFREE page.
+ *
+ * This routine hands out NOFREE pages from higher-order
+ * physical memory blocks in order to reduce memory fragmentation.
+ * When a NOFREE for a given domain chunk is used up,
+ * the routine will try to fetch a new one from the freelists
+ * and discard the old one.
+ */
+static vm_page_t
+vm_page_alloc_nofree_domain(int domain, int req)
+{
+ vm_page_t m;
+ struct vm_domain *vmd;
+ struct vm_nofreeq *nqp;
+
+ KASSERT((req & VM_ALLOC_NOFREE) != 0, ("invalid request %#x", req));
+
+ vmd = VM_DOMAIN(domain);
+ nqp = &vmd->vmd_nofreeq;
+ vm_domain_free_lock(vmd);
+ if (nqp->offs >= (1 << VM_NOFREE_IMPORT_ORDER) || nqp->ma == NULL) {
+ if (!vm_domain_allocate(vmd, req,
+ 1 << VM_NOFREE_IMPORT_ORDER)) {
+ vm_domain_free_unlock(vmd);
+ return (NULL);
+ }
+ nqp->ma = vm_phys_alloc_pages(domain, VM_FREEPOOL_DEFAULT,
+ VM_LEVEL_0_ORDER);
+ if (nqp->ma == NULL) {
+ vm_domain_freecnt_inc(vmd, 1 << VM_NOFREE_IMPORT_ORDER);
+ vm_domain_free_unlock(vmd);
+ return (NULL);
+ }
+ nqp->offs = 0;
+ }
+ m = &nqp->ma[nqp->offs++];
+ vm_domain_free_unlock(vmd);
+
+ return (m);
+}
+
vm_page_t
vm_page_alloc_noobj(int req)
{
diff --git a/sys/vm/vm_pagequeue.h b/sys/vm/vm_pagequeue.h
index 7e133ec947b4..86863a0a6400 100644
--- a/sys/vm/vm_pagequeue.h
+++ b/sys/vm/vm_pagequeue.h
@@ -246,6 +246,10 @@ struct vm_domain {
u_int vmd_domain; /* (c) Domain number. */
u_int vmd_page_count; /* (c) Total page count. */
long vmd_segs; /* (c) bitmask of the segments */
+ struct vm_nofreeq {
+ vm_page_t ma;
+ int offs;
+ } vmd_nofreeq; /* (f) NOFREE page bump allocator. */
u_int __aligned(CACHE_LINE_SIZE) vmd_free_count; /* (a,f) free page
count */
u_int vmd_pageout_deficit; /* (a) Estimated number of pages
deficit */
uint8_t vmd_pad[CACHE_LINE_SIZE - (sizeof(u_int) * 2)];
