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x86: fix Xorg startup/shutdown slowdown with PAT 

Rene Herman reported significant Xorg startup/shutdown slowdown due
to PAT. It turns out that the memtype list has thousands of entries.

Add cached_entry to list add routine, in order to speed up the
lookup for sequential reserve_memtype calls.

Reported-by: Rene Herman <rene.herman@keyaccess.nl>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Venki Pallipadi 2008-08-19 16:28:01 -07:00 committed by Ingo Molnar
parent c6744955d0
commit 80c5e73d60
1 changed files with 31 additions and 2 deletions
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33
arch/x86/mm/pat.c
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@ -207,6 +207,9 @@ static int chk_conflict(struct memtype *new, struct memtype *entry,
return -EBUSY;
}
static struct memtype *cached_entry;
static u64 cached_start;
/*
* req_type typically has one of the:
* - _PAGE_CACHE_WB
@ -280,11 +283,17 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
spin_lock(&memtype_lock);
if (cached_entry && start >= cached_start)
entry = cached_entry;
else
entry = list_entry(&memtype_list, struct memtype, nd);
/* Search for existing mapping that overlaps the current range */
where = NULL;
list_for_each_entry(entry, &memtype_list, nd) {
list_for_each_entry_continue(entry, &memtype_list, nd) {
if (end <= entry->start) {
where = entry->nd.prev;
cached_entry = list_entry(where, struct memtype, nd);
break;
} else if (start <= entry->start) { /* end > entry->start */
err = chk_conflict(new, entry, new_type);
@ -292,6 +301,8 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
dprintk("Overlap at 0x%Lx-0x%Lx\n",
entry->start, entry->end);
where = entry->nd.prev;
cached_entry = list_entry(where,
struct memtype, nd);
}
break;
} else if (start < entry->end) { /* start > entry->start */
@ -299,7 +310,20 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
if (!err) {
dprintk("Overlap at 0x%Lx-0x%Lx\n",
entry->start, entry->end);
where = &entry->nd;
cached_entry = list_entry(entry->nd.prev,
struct memtype, nd);
/*
* Move to right position in the linked
* list to add this new entry
*/
list_for_each_entry_continue(entry,
&memtype_list, nd) {
if (start <= entry->start) {
where = entry->nd.prev;
break;
}
}
}
break;
}
@ -314,6 +338,8 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
return err;
}
cached_start = start;
if (where)
list_add(&new->nd, where);
else
@ -343,6 +369,9 @@ int free_memtype(u64 start, u64 end)
spin_lock(&memtype_lock);
list_for_each_entry(entry, &memtype_list, nd) {
if (entry->start == start && entry->end == end) {
if (cached_entry == entry || cached_start == start)
cached_entry = NULL;
list_del(&entry->nd);
kfree(entry);
err = 0;