Date: Fri, 2 Jul 2010 19:59:18 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r209650 - head/sys/vm Message-ID: <201007021959.o62JxIYH091917@svn.freebsd.org>
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Author: alc Date: Fri Jul 2 19:59:18 2010 New Revision: 209650 URL: http://svn.freebsd.org/changeset/base/209650 Log: Use vm_page_prev() instead of vm_page_lookup() in the implementation of vm_fault()'s automatic delete-behind heuristic. vm_page_prev() is typically faster. Modified: head/sys/vm/vm_fault.c Modified: head/sys/vm/vm_fault.c ============================================================================== --- head/sys/vm/vm_fault.c Fri Jul 2 17:22:15 2010 (r209649) +++ head/sys/vm/vm_fault.c Fri Jul 2 19:59:18 2010 (r209650) @@ -214,7 +214,7 @@ vm_fault(vm_map_t map, vm_offset_t vaddr boolean_t growstack, wired; int map_generation; vm_object_t next_object; - vm_page_t marray[VM_FAULT_READ]; + vm_page_t marray[VM_FAULT_READ], mt, mt_prev; int hardfault; int faultcount, ahead, behind, alloc_req; struct faultstate fs; @@ -465,26 +465,28 @@ readrest: fs.first_object->type != OBJT_DEVICE && fs.first_object->type != OBJT_PHYS && fs.first_object->type != OBJT_SG) { - vm_pindex_t firstpindex, tmppindex; + vm_pindex_t firstpindex; if (fs.first_pindex < 2 * VM_FAULT_READ) firstpindex = 0; else firstpindex = fs.first_pindex - 2 * VM_FAULT_READ; + mt = fs.first_object != fs.object ? + fs.first_m : fs.m; + KASSERT(mt != NULL, ("vm_fault: missing mt")); + KASSERT((mt->oflags & VPO_BUSY) != 0, + ("vm_fault: mt %p not busy", mt)); + mt_prev = vm_page_prev(mt); /* * note: partially valid pages cannot be * included in the lookahead - NFS piecemeal * writes will barf on it badly. */ - for (tmppindex = fs.first_pindex - 1; - tmppindex >= firstpindex; - --tmppindex) { - vm_page_t mt; - - mt = vm_page_lookup(fs.first_object, tmppindex); - if (mt == NULL || (mt->valid != VM_PAGE_BITS_ALL)) - break; + while ((mt = mt_prev) != NULL && + mt->pindex >= firstpindex && + mt->valid == VM_PAGE_BITS_ALL) { + mt_prev = vm_page_prev(mt); if (mt->busy || (mt->oflags & VPO_BUSY)) continue;
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