Re: 2.6.22 -mm merge plans -- vm bugfixes
From: Nick Piggin
Date: Fri May 04 2007 - 05:23:53 EST
Nick Piggin wrote:
Christoph Hellwig wrote:
Is that every fork/exec or just under certain cicumstances?
A 5% regression on every fork/exec is not acceptable.
Well after patch2, G5 fork is 3% and exec is 1%, I'd say the P4
numbers will be improved as well with that patch. Then if we have
specific lock/unlock bitops, I hope it should reduce that further.
OK, with the races and missing barriers fixed from the previous patch,
plus the attached one added (+patch3), numbers are better again (I'm not
sure if I have the ppc barriers correct though).
These ops could also be put to use in bit spinlocks, buffer lock, and
probably a few other places too.
2.6.21 1.49-1.51 164.6-170.8 741.8-760.3
+patch 1.71-1.73 175.2-180.8 780.5-794.2
+patch2 1.61-1.63 169.8-175.0 748.6-757.0
+patch3 1.54-1.57 165.6-170.9 748.5-757.5
So fault performance goes to under 5%, fork is in the noise, exec is
still up 1%, but maybe that's noise or cache effects again.
--
SUSE Labs, Novell Inc.
Index: linux-2.6/include/asm-powerpc/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-powerpc/bitops.h 2007-05-04 16:08:20.000000000 +1000
+++ linux-2.6/include/asm-powerpc/bitops.h 2007-05-04 16:14:39.000000000 +1000
@@ -87,6 +87,24 @@
: "cc" );
}
+static __inline__ void clear_bit_unlock(int nr, volatile unsigned long *addr)
+{
+ unsigned long old;
+ unsigned long mask = BITOP_MASK(nr);
+ unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
+
+ __asm__ __volatile__(
+ LWSYNC_ON_SMP
+"1:" PPC_LLARX "%0,0,%3 # clear_bit_unlock\n"
+ "andc %0,%0,%2\n"
+ PPC405_ERR77(0,%3)
+ PPC_STLCX "%0,0,%3\n"
+ "bne- 1b"
+ : "=&r" (old), "+m" (*p)
+ : "r" (mask), "r" (p)
+ : "cc" );
+}
+
static __inline__ void change_bit(int nr, volatile unsigned long *addr)
{
unsigned long old;
@@ -126,6 +144,27 @@
return (old & mask) != 0;
}
+static __inline__ int test_and_set_bit_lock(unsigned long nr,
+ volatile unsigned long *addr)
+{
+ unsigned long old, t;
+ unsigned long mask = BITOP_MASK(nr);
+ unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
+
+ __asm__ __volatile__(
+"1:" PPC_LLARX "%0,0,%3 # test_and_set_bit_lock\n"
+ "or %1,%0,%2 \n"
+ PPC405_ERR77(0,%3)
+ PPC_STLCX "%1,0,%3 \n"
+ "bne- 1b"
+ ISYNC_ON_SMP
+ : "=&r" (old), "=&r" (t)
+ : "r" (mask), "r" (p)
+ : "cc", "memory");
+
+ return (old & mask) != 0;
+}
+
static __inline__ int test_and_clear_bit(unsigned long nr,
volatile unsigned long *addr)
{
Index: linux-2.6/include/linux/pagemap.h
===================================================================
--- linux-2.6.orig/include/linux/pagemap.h 2007-05-04 16:14:36.000000000 +1000
+++ linux-2.6/include/linux/pagemap.h 2007-05-04 16:17:34.000000000 +1000
@@ -136,13 +136,18 @@
extern void FASTCALL(__wait_on_page_locked(struct page *page));
extern void FASTCALL(unlock_page(struct page *page));
+static inline int trylock_page(struct page *page)
+{
+ return (likely(!TestSetPageLocked_Lock(page)));
+}
+
/*
* lock_page may only be called if we have the page's inode pinned.
*/
static inline void lock_page(struct page *page)
{
might_sleep();
- if (unlikely(TestSetPageLocked(page)))
+ if (!trylock_page(page))
__lock_page(page);
}
@@ -153,7 +158,7 @@
static inline void lock_page_nosync(struct page *page)
{
might_sleep();
- if (unlikely(TestSetPageLocked(page)))
+ if (!trylock_page(page))
__lock_page_nosync(page);
}
Index: linux-2.6/drivers/scsi/sg.c
===================================================================
--- linux-2.6.orig/drivers/scsi/sg.c 2007-04-12 14:35:08.000000000 +1000
+++ linux-2.6/drivers/scsi/sg.c 2007-05-04 16:23:27.000000000 +1000
@@ -1734,7 +1734,7 @@
*/
flush_dcache_page(pages[i]);
/* ?? Is locking needed? I don't think so */
- /* if (TestSetPageLocked(pages[i]))
+ /* if (!trylock_page(pages[i]))
goto out_unlock; */
}
Index: linux-2.6/fs/cifs/file.c
===================================================================
--- linux-2.6.orig/fs/cifs/file.c 2007-04-12 14:35:09.000000000 +1000
+++ linux-2.6/fs/cifs/file.c 2007-05-04 16:23:36.000000000 +1000
@@ -1229,7 +1229,7 @@
if (first < 0)
lock_page(page);
- else if (TestSetPageLocked(page))
+ else if (!trylock_page(page))
break;
if (unlikely(page->mapping != mapping)) {
Index: linux-2.6/fs/jbd/commit.c
===================================================================
--- linux-2.6.orig/fs/jbd/commit.c 2007-04-12 14:35:09.000000000 +1000
+++ linux-2.6/fs/jbd/commit.c 2007-05-04 16:23:30.000000000 +1000
@@ -64,7 +64,7 @@
goto nope;
/* OK, it's a truncated page */
- if (TestSetPageLocked(page))
+ if (!trylock_page(page))
goto nope;
page_cache_get(page);
Index: linux-2.6/fs/jbd2/commit.c
===================================================================
--- linux-2.6.orig/fs/jbd2/commit.c 2007-04-12 14:35:09.000000000 +1000
+++ linux-2.6/fs/jbd2/commit.c 2007-05-04 16:23:40.000000000 +1000
@@ -64,7 +64,7 @@
goto nope;
/* OK, it's a truncated page */
- if (TestSetPageLocked(page))
+ if (!trylock_page(page))
goto nope;
page_cache_get(page);
Index: linux-2.6/fs/xfs/linux-2.6/xfs_aops.c
===================================================================
--- linux-2.6.orig/fs/xfs/linux-2.6/xfs_aops.c 2007-03-05 15:17:25.000000000 +1100
+++ linux-2.6/fs/xfs/linux-2.6/xfs_aops.c 2007-05-04 16:23:33.000000000 +1000
@@ -601,7 +601,7 @@
} else
pg_offset = PAGE_CACHE_SIZE;
- if (page->index == tindex && !TestSetPageLocked(page)) {
+ if (page->index == tindex && trylock_page(page)) {
len = xfs_probe_page(page, pg_offset, mapped);
unlock_page(page);
}
@@ -685,7 +685,7 @@
if (page->index != tindex)
goto fail;
- if (TestSetPageLocked(page))
+ if (!trylock_page(page))
goto fail;
if (PageWriteback(page))
goto fail_unlock_page;
Index: linux-2.6/include/linux/page-flags.h
===================================================================
--- linux-2.6.orig/include/linux/page-flags.h 2007-05-03 08:38:53.000000000 +1000
+++ linux-2.6/include/linux/page-flags.h 2007-05-04 16:18:23.000000000 +1000
@@ -116,8 +116,12 @@
set_bit(PG_locked, &(page)->flags)
#define TestSetPageLocked(page) \
test_and_set_bit(PG_locked, &(page)->flags)
+#define TestSetPageLocked_Lock(page) \
+ test_and_set_bit_lock(PG_locked, &(page)->flags)
#define ClearPageLocked(page) \
clear_bit(PG_locked, &(page)->flags)
+#define ClearPageLocked_Unlock(page) \
+ clear_bit_unlock(PG_locked, &(page)->flags)
#define TestClearPageLocked(page) \
test_and_clear_bit(PG_locked, &(page)->flags)
Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c 2007-05-02 15:00:28.000000000 +1000
+++ linux-2.6/mm/memory.c 2007-05-04 16:19:12.000000000 +1000
@@ -1550,7 +1550,7 @@
* not dirty accountable.
*/
if (PageAnon(old_page)) {
- if (!TestSetPageLocked(old_page)) {
+ if (trylock_page(old_page)) {
reuse = can_share_swap_page(old_page);
unlock_page(old_page);
}
Index: linux-2.6/mm/migrate.c
===================================================================
--- linux-2.6.orig/mm/migrate.c 2007-05-02 14:48:36.000000000 +1000
+++ linux-2.6/mm/migrate.c 2007-05-04 16:19:15.000000000 +1000
@@ -569,7 +569,7 @@
* establishing additional references. We are the only one
* holding a reference to the new page at this point.
*/
- if (TestSetPageLocked(newpage))
+ if (!trylock_page(newpage))
BUG();
/* Prepare mapping for the new page.*/
@@ -621,7 +621,7 @@
goto move_newpage;
rc = -EAGAIN;
- if (TestSetPageLocked(page)) {
+ if (!trylock_page(page)) {
if (!force)
goto move_newpage;
lock_page(page);
Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c 2007-04-13 20:48:04.000000000 +1000
+++ linux-2.6/mm/rmap.c 2007-05-04 16:19:18.000000000 +1000
@@ -426,7 +426,7 @@
referenced += page_referenced_anon(page);
else if (is_locked)
referenced += page_referenced_file(page);
- else if (TestSetPageLocked(page))
+ else if (!trylock_page(page))
referenced++;
else {
if (page->mapping)
Index: linux-2.6/mm/shmem.c
===================================================================
--- linux-2.6.orig/mm/shmem.c 2007-05-02 15:00:26.000000000 +1000
+++ linux-2.6/mm/shmem.c 2007-05-04 16:19:22.000000000 +1000
@@ -1155,7 +1155,7 @@
}
/* We have to do this with page locked to prevent races */
- if (TestSetPageLocked(swappage)) {
+ if (!trylock_page(swappage)) {
shmem_swp_unmap(entry);
spin_unlock(&info->lock);
wait_on_page_locked(swappage);
@@ -1214,7 +1214,7 @@
shmem_swp_unmap(entry);
filepage = find_get_page(mapping, idx);
if (filepage &&
- (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
+ (!PageUptodate(filepage) || !trylock_page(filepage))) {
spin_unlock(&info->lock);
wait_on_page_locked(filepage);
page_cache_release(filepage);
Index: linux-2.6/mm/swap.c
===================================================================
--- linux-2.6.orig/mm/swap.c 2007-04-12 14:35:11.000000000 +1000
+++ linux-2.6/mm/swap.c 2007-05-04 16:19:28.000000000 +1000
@@ -412,7 +412,7 @@
for (i = 0; i < pagevec_count(pvec); i++) {
struct page *page = pvec->pages[i];
- if (PagePrivate(page) && !TestSetPageLocked(page)) {
+ if (PagePrivate(page) && trylock_page(page)) {
if (PagePrivate(page))
try_to_release_page(page, 0);
unlock_page(page);
Index: linux-2.6/mm/swap_state.c
===================================================================
--- linux-2.6.orig/mm/swap_state.c 2007-04-24 10:39:57.000000000 +1000
+++ linux-2.6/mm/swap_state.c 2007-05-04 16:19:32.000000000 +1000
@@ -252,7 +252,7 @@
*/
static inline void free_swap_cache(struct page *page)
{
- if (PageSwapCache(page) && !TestSetPageLocked(page)) {
+ if (PageSwapCache(page) && trylock_page(page)) {
remove_exclusive_swap_page(page);
unlock_page(page);
}
Index: linux-2.6/mm/swapfile.c
===================================================================
--- linux-2.6.orig/mm/swapfile.c 2007-04-24 10:39:55.000000000 +1000
+++ linux-2.6/mm/swapfile.c 2007-05-04 16:19:25.000000000 +1000
@@ -401,7 +401,7 @@
if (p) {
if (swap_entry_free(p, swp_offset(entry)) == 1) {
page = find_get_page(&swapper_space, entry.val);
- if (page && unlikely(TestSetPageLocked(page))) {
+ if (page && unlikely(!trylock_page(page))) {
page_cache_release(page);
page = NULL;
}
Index: linux-2.6/mm/truncate.c
===================================================================
--- linux-2.6.orig/mm/truncate.c 2007-05-02 15:00:27.000000000 +1000
+++ linux-2.6/mm/truncate.c 2007-05-04 16:19:35.000000000 +1000
@@ -185,7 +185,7 @@
if (page_index > next)
next = page_index;
next++;
- if (TestSetPageLocked(page))
+ if (!trylock_page(page))
continue;
if (PageWriteback(page)) {
unlock_page(page);
@@ -291,7 +291,7 @@
pgoff_t index;
int lock_failed;
- lock_failed = TestSetPageLocked(page);
+ lock_failed = !trylock_page(page);
/*
* We really shouldn't be looking at the ->index of an
Index: linux-2.6/mm/vmscan.c
===================================================================
--- linux-2.6.orig/mm/vmscan.c 2007-04-24 10:39:56.000000000 +1000
+++ linux-2.6/mm/vmscan.c 2007-05-04 16:19:38.000000000 +1000
@@ -466,7 +466,7 @@
page = lru_to_page(page_list);
list_del(&page->lru);
- if (TestSetPageLocked(page))
+ if (!trylock_page(page))
goto keep;
VM_BUG_ON(PageActive(page));
@@ -538,7 +538,7 @@
* A synchronous write - probably a ramdisk. Go
* ahead and try to reclaim the page.
*/
- if (TestSetPageLocked(page))
+ if (!trylock_page(page))
goto keep;
if (PageDirty(page) || PageWriteback(page))
goto keep_locked;