Date: Fri, 11 Aug 2017 03:09:11 +0000 (UTC) From: Mark Johnston <markj@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r322391 - head/sys/vm Message-ID: <201708110309.v7B39C7d044250@repo.freebsd.org>
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Author: markj Date: Fri Aug 11 03:09:11 2017 New Revision: 322391 URL: https://svnweb.freebsd.org/changeset/base/322391 Log: Micro-optimize kmem_unback(). We can remove some unnecessary object radix tree lookups by using the object memq to iterate over pages in the specified range. This does not, however, eliminate the lookup needed in vm_page_free_toq() to remove each tree entry. Reviewed by: alc, kib (previous revision) MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D11945 Modified: head/sys/vm/vm_kern.c Modified: head/sys/vm/vm_kern.c ============================================================================== --- head/sys/vm/vm_kern.c Fri Aug 11 00:43:50 2017 (r322390) +++ head/sys/vm/vm_kern.c Fri Aug 11 03:09:11 2017 (r322391) @@ -386,17 +386,19 @@ retry: void kmem_unback(vm_object_t object, vm_offset_t addr, vm_size_t size) { - vm_page_t m; - vm_offset_t i, offset; + vm_page_t m, next; + vm_offset_t end, offset; KASSERT(object == kmem_object || object == kernel_object, ("kmem_unback: only supports kernel objects.")); pmap_remove(kernel_pmap, addr, addr + size); offset = addr - VM_MIN_KERNEL_ADDRESS; + end = offset + size; VM_OBJECT_WLOCK(object); - for (i = 0; i < size; i += PAGE_SIZE) { - m = vm_page_lookup(object, atop(offset + i)); + for (m = vm_page_lookup(object, atop(offset)); offset < end; + offset += PAGE_SIZE, m = next) { + next = vm_page_next(m); vm_page_unwire(m, PQ_NONE); vm_page_free(m); }
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