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vm: Add a KVA arena for M_NEVERFREED allocations

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This patch adds a new KVA arena for separating M_NEVERFREED allocations.
Separating KVAs for pages that are never freed should facilitate
superpage promotion in the kernel.

Differential Revision:	https://reviews.freebsd.org/D45997
Reviewed by:	alc, kib, markj
Tested by:	alc
This commit is contained in:
Bojan Novković 2024-07-16 16:14:30 +02:00
parent a8693e89e3
commit 3f32a7e4ee
2 changed files with 17 additions and 5 deletions
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21
sys/vm/vm_kern.c
View File

@ -473,10 +473,12 @@ kmem_malloc_domain(int domain, vm_size_t size, int flags)
vm_size_t asize;
int rv;
if (__predict_true((flags & M_EXEC) == 0))
if (__predict_true((flags & (M_EXEC | M_NEVERFREED)) == 0))
arena = vm_dom[domain].vmd_kernel_arena;
else
else if ((flags & M_EXEC) != 0)
arena = vm_dom[domain].vmd_kernel_rwx_arena;
else
arena = vm_dom[domain].vmd_kernel_nofree_arena;
asize = round_page(size);
if (vmem_alloc(arena, asize, flags | M_BESTFIT, &addr))
return (0);
@ -882,20 +884,29 @@ kmem_init(vm_offset_t start, vm_offset_t end)
/*
* In architectures with superpages, maintain separate arenas
* for allocations with permissions that differ from the
* "standard" read/write permissions used for kernel memory,
* so as not to inhibit superpage promotion.
* "standard" read/write permissions used for kernel memory
* and pages that are never released, so as not to inhibit
* superpage promotion.
*
* Use the base import quantum since this arena is rarely used.
* Use the base import quantum since these arenas are rarely
* used.
*/
#if VM_NRESERVLEVEL > 0
vm_dom[domain].vmd_kernel_rwx_arena = vmem_create(
"kernel rwx arena domain", 0, 0, PAGE_SIZE, 0, M_WAITOK);
vm_dom[domain].vmd_kernel_nofree_arena = vmem_create(
"kernel NOFREE arena domain", 0, 0, PAGE_SIZE, 0, M_WAITOK);
vmem_set_import(vm_dom[domain].vmd_kernel_rwx_arena,
kva_import_domain, (vmem_release_t *)vmem_xfree,
kernel_arena, KVA_QUANTUM);
vmem_set_import(vm_dom[domain].vmd_kernel_nofree_arena,
kva_import_domain, (vmem_release_t *)vmem_xfree,
kernel_arena, KVA_QUANTUM);
#else
vm_dom[domain].vmd_kernel_rwx_arena =
vm_dom[domain].vmd_kernel_arena;
vm_dom[domain].vmd_kernel_nofree_arena =
vm_dom[domain].vmd_kernel_arena;
#endif
}

1
sys/vm/vm_pagequeue.h
View File

@ -243,6 +243,7 @@ struct vm_domain {
} vmd_pgcache[VM_NFREEPOOL];
struct vmem *vmd_kernel_arena; /* (c) per-domain kva R/W arena. */
struct vmem *vmd_kernel_rwx_arena; /* (c) per-domain kva R/W/X arena. */
struct vmem *vmd_kernel_nofree_arena; /* (c) per-domain kva NOFREE arena. */
u_int vmd_domain; /* (c) Domain number. */
u_int vmd_page_count; /* (c) Total page count. */
long vmd_segs; /* (c) bitmask of the segments */