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Simplify the implementation of vm_fault_additional_pages() based upon the

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object's memq being ordered.  Specifically, replace repeated calls to
vm_page_lookup() by two simple constant-time operations.

Reviewed by: tegge
This commit is contained in:
Alan Cox 2006-05-13 20:05:44 +00:00
parent 1e1de0e499
commit 8f8790a76d
1 changed files with 5 additions and 12 deletions
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17
sys/vm/vm_fault.c
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@ -1301,14 +1301,9 @@ vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage)
startpindex = pindex - rbehind;
}
for (tpindex = pindex - 1; tpindex >= startpindex; tpindex -= 1) {
if (vm_page_lookup(object, tpindex)) {
startpindex = tpindex + 1;
break;
}
if (tpindex == 0)
break;
}
if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL &&
rtm->pindex >= startpindex)
startpindex = rtm->pindex + 1;
for (i = 0, tpindex = startpindex; tpindex < pindex; i++, tpindex++) {
@ -1342,15 +1337,13 @@ vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage)
* scan forward for the read ahead pages
*/
endpindex = tpindex + rahead;
if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex)
endpindex = rtm->pindex;
if (endpindex > object->size)
endpindex = object->size;
for (; tpindex < endpindex; i++, tpindex++) {
if (vm_page_lookup(object, tpindex)) {
break;
}
rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
if (rtm == NULL) {
break;