From 80c5e73d6028e0f03ab0c70e7c4cbf98ac2e0c43 Mon Sep 17 00:00:00 2001 From: Venki Pallipadi Date: Tue, 19 Aug 2008 16:28:01 -0700 Subject: [PATCH] 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 Signed-off-by: Venkatesh Pallipadi Signed-off-by: Ingo Molnar --- arch/x86/mm/pat.c | 33 +++++++++++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 2fe3091..bb6e8a2 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -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; -- 2.7.4