Although we perform path compression to reduce the height of the trie and
the number of interior nodes, we always create a level zero interior node at the root of every non-empty trie, even when that node is not strictly necessary, i.e., it has only one child. This change is the first step in eliminating those unnecessary level zero interior nodes. Specifically, it updates all of the lookup functions so that they do not require a level zero interior node at the root. Reviewed by: attilio, jeff (an earlier version) Sponsored by: EMC / Isilon Storage Division
This commit is contained in:
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=249427
@ -270,11 +270,7 @@ vm_radix_addlev(vm_pindex_t *idx, boolean_t *levels, uint16_t ilev)
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for (; levels[ilev] == FALSE ||
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vm_radix_slot(*idx, ilev) == (VM_RADIX_COUNT - 1); ilev--)
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if (ilev == 0)
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break;
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KASSERT(ilev > 0 || levels[0],
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("%s: levels back-scanning problem", __func__));
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if (ilev == 0 && vm_radix_slot(*idx, ilev) == (VM_RADIX_COUNT - 1))
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return (1);
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return (1);
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wrapidx = *idx;
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*idx = vm_radix_trimkey(*idx, ilev);
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*idx += VM_RADIX_UNITLEVEL(ilev);
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@ -295,11 +291,7 @@ vm_radix_declev(vm_pindex_t *idx, boolean_t *levels, uint16_t ilev)
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for (; levels[ilev] == FALSE ||
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vm_radix_slot(*idx, ilev) == 0; ilev--)
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if (ilev == 0)
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break;
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KASSERT(ilev > 0 || levels[0],
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("%s: levels back-scanning problem", __func__));
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if (ilev == 0 && vm_radix_slot(*idx, ilev) == 0)
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return (1);
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return (1);
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wrapidx = *idx;
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*idx = vm_radix_trimkey(*idx, ilev);
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*idx |= VM_RADIX_UNITLEVEL(ilev) - 1;
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@ -474,17 +466,16 @@ vm_radix_lookup(struct vm_radix *rtree, vm_pindex_t index)
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rnode = vm_radix_getroot(rtree);
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while (rnode != NULL) {
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if (vm_radix_keybarr(rnode, index))
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return (NULL);
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slot = vm_radix_slot(index, rnode->rn_clev);
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rnode = rnode->rn_child[slot];
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if (vm_radix_isleaf(rnode)) {
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m = vm_radix_topage(rnode);
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if (m->pindex == index)
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return (m);
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else
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return (NULL);
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}
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break;
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} else if (vm_radix_keybarr(rnode, index))
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break;
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slot = vm_radix_slot(index, rnode->rn_clev);
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rnode = rnode->rn_child[slot];
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}
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return (NULL);
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}
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@ -505,12 +496,21 @@ vm_radix_lookup_ge(struct vm_radix *rtree, vm_pindex_t index)
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int loops = 0;
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#endif
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rnode = vm_radix_getroot(rtree);
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if (rnode == NULL)
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return (NULL);
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else if (vm_radix_isleaf(rnode)) {
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m = vm_radix_topage(rnode);
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if (m->pindex >= index)
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return (m);
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else
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return (NULL);
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}
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restart:
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KASSERT(++loops < 1000, ("%s: too many loops", __func__));
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for (difflev = 0; difflev < (VM_RADIX_LIMIT + 1); difflev++)
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maplevels[difflev] = FALSE;
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rnode = vm_radix_getroot(rtree);
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while (rnode != NULL) {
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for (;;) {
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maplevels[rnode->rn_clev] = TRUE;
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/*
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@ -532,6 +532,7 @@ vm_radix_lookup_ge(struct vm_radix *rtree, vm_pindex_t index)
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} else
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index = vm_radix_trimkey(rnode->rn_owner,
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difflev);
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rnode = vm_radix_getroot(rtree);
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goto restart;
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}
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slot = vm_radix_slot(index, rnode->rn_clev);
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@ -572,6 +573,7 @@ vm_radix_lookup_ge(struct vm_radix *rtree, vm_pindex_t index)
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if (rnode->rn_clev == 0 || vm_radix_addlev(&index, maplevels,
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rnode->rn_clev - 1) > 0)
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break;
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rnode = vm_radix_getroot(rtree);
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goto restart;
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descend:
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rnode = child;
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@ -595,12 +597,21 @@ vm_radix_lookup_le(struct vm_radix *rtree, vm_pindex_t index)
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int loops = 0;
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#endif
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rnode = vm_radix_getroot(rtree);
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if (rnode == NULL)
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return (NULL);
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else if (vm_radix_isleaf(rnode)) {
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m = vm_radix_topage(rnode);
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if (m->pindex <= index)
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return (m);
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else
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return (NULL);
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}
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restart:
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KASSERT(++loops < 1000, ("%s: too many loops", __func__));
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for (difflev = 0; difflev < (VM_RADIX_LIMIT + 1); difflev++)
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maplevels[difflev] = FALSE;
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rnode = vm_radix_getroot(rtree);
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while (rnode != NULL) {
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for (;;) {
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maplevels[rnode->rn_clev] = TRUE;
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/*
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@ -622,6 +633,7 @@ vm_radix_lookup_le(struct vm_radix *rtree, vm_pindex_t index)
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} else if (vm_radix_declev(&index, maplevels,
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difflev) > 0)
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break;
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rnode = vm_radix_getroot(rtree);
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goto restart;
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}
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slot = vm_radix_slot(index, rnode->rn_clev);
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@ -663,6 +675,7 @@ vm_radix_lookup_le(struct vm_radix *rtree, vm_pindex_t index)
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if (rnode->rn_clev == 0 || vm_radix_declev(&index, maplevels,
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rnode->rn_clev - 1) > 0)
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break;
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rnode = vm_radix_getroot(rtree);
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goto restart;
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descend:
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rnode = child;
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