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SubjectRe: [PATCH] Align VM locks, new spinlock patch
Andrew Morton wrote:
> I think the coding can be simplified somewhat. How does this
> look?
> ...

Looks fine, it makes the code more common between UP and SMP.
I consolidated the changes and appended the new version below.


The peak throughput results (MB/sec) for dbench on 2.4.10:

CPU 2.4.10 2.4.10 + improvement
spinlock patch by patch

U 102,9 103,0 0,0%
1 95,1 96,9 1,9%
2 155,5 156,0 0,3%
4 206,9 222,1 7,3%
8 194,9 233,7 19,9%

Throughput (MB/sec) for dbench with 8 clients on 8 CPUs:
CPU 2.4.10 2.4.10 + improvement
spinlock patch by patch
8 173,9 223,0 28,2%


Juergen

______________________________________________________________
Juergen Doelle
IBM Linux Technology Center - kernel performance
jdoelle@de.ibm.com


= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

--- linux/include/linux/spinlock.h.orig Tue Sep 25 09:05:09 2001
+++ linux/include/linux/spinlock.h Tue Sep 25 11:42:51 2001
@@ -133,4 +133,20 @@
extern int atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
#endif

+#ifdef CONFIG_SMP
+#include <linux/cache.h>
+
+typedef union {
+ spinlock_t lock;
+ char fill_up[(SMP_CACHE_BYTES)];
+} spinlock_cacheline_t __attribute__ ((aligned(SMP_CACHE_BYTES)));
+
+#else /* SMP */
+
+typedef struct {
+ spinlock_t lock;
+} spinlock_cacheline_t;
+
+
+#endif
#endif /* __LINUX_SPINLOCK_H */
--- linux/include/linux/swap.h.orig Tue Sep 25 09:59:15 2001
+++ linux/include/linux/swap.h Tue Sep 25 11:42:51 2001
@@ -86,7 +86,10 @@
extern atomic_t nr_async_pages;
extern atomic_t page_cache_size;
extern atomic_t buffermem_pages;
-extern spinlock_t pagecache_lock;
+
+extern spinlock_cacheline_t pagecache_lock_cacheline;
+#define pagecache_lock (pagecache_lock_cacheline.lock)
+
extern void __remove_inode_page(struct page *);

/* Incomplete types for prototype declarations: */
@@ -159,7 +162,8 @@
extern unsigned long swap_cache_find_success;
#endif

-extern spinlock_t pagemap_lru_lock;
+extern spinlock_cacheline_t pagemap_lru_lock_cacheline;
+#define pagemap_lru_lock pagemap_lru_lock_cacheline.lock

extern void FASTCALL(mark_page_accessed(struct page *));

--- linux/include/asm-i386/smplock.h.orig Tue Sep 25 11:29:51 2001
+++ linux/include/asm-i386/smplock.h Tue Sep 25 11:42:52 2001
@@ -8,7 +8,8 @@
#include <linux/sched.h>
#include <asm/current.h>

-extern spinlock_t kernel_flag;
+extern spinlock_cacheline_t kernel_flag_cacheline;
+#define kernel_flag kernel_flag_cacheline.lock

#define kernel_locked() spin_is_locked(&kernel_flag)

--- linux/arch/i386/kernel/i386_ksyms.c.orig Tue Sep 25 09:14:57 2001
+++ linux/arch/i386/kernel/i386_ksyms.c Tue Sep 25 10:13:06 2001
@@ -120,7 +120,7 @@

#ifdef CONFIG_SMP
EXPORT_SYMBOL(cpu_data);
-EXPORT_SYMBOL(kernel_flag);
+EXPORT_SYMBOL(kernel_flag_cacheline);
EXPORT_SYMBOL(smp_num_cpus);
EXPORT_SYMBOL(cpu_online_map);
EXPORT_SYMBOL_NOVERS(__write_lock_failed);
--- linux/arch/i386/kernel/smp.c.orig Tue Sep 25 09:15:16 2001
+++ linux/arch/i386/kernel/smp.c Tue Sep 25 10:13:06 2001
@@ -101,7 +101,7 @@
*/

/* The 'big kernel lock' */
-spinlock_t kernel_flag = SPIN_LOCK_UNLOCKED;
+spinlock_cacheline_t kernel_flag_cacheline = {SPIN_LOCK_UNLOCKED};

struct tlb_state cpu_tlbstate[NR_CPUS] = {[0 ... NR_CPUS-1] = { &init_mm, 0 }};

--- linux/fs/buffer.c.orig Tue Sep 25 09:15:47 2001
+++ linux/fs/buffer.c Wed Sep 26 12:17:29 2001
@@ -81,7 +81,10 @@
static rwlock_t hash_table_lock = RW_LOCK_UNLOCKED;

static struct buffer_head *lru_list[NR_LIST];
-static spinlock_t lru_list_lock = SPIN_LOCK_UNLOCKED;
+
+static spinlock_cacheline_t lru_list_lock_cacheline = {SPIN_LOCK_UNLOCKED};
+#define lru_list_lock lru_list_lock_cacheline.lock
+
static int nr_buffers_type[NR_LIST];
static unsigned long size_buffers_type[NR_LIST];

--- linux/mm/filemap.c.orig Tue Sep 25 09:16:06 2001
+++ linux/mm/filemap.c Tue Sep 25 10:13:06 2001
@@ -46,12 +46,13 @@
unsigned int page_hash_bits;
struct page **page_hash_table;

-spinlock_t pagecache_lock ____cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
+spinlock_cacheline_t pagecache_lock_cacheline = {SPIN_LOCK_UNLOCKED};
+
/*
* NOTE: to avoid deadlocking you must never acquire the pagecache_lock with
* the pagemap_lru_lock held.
*/
-spinlock_t pagemap_lru_lock ____cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
+spinlock_cacheline_t pagemap_lru_lock_cacheline = {SPIN_LOCK_UNLOCKED};

#define CLUSTER_PAGES (1 << page_cluster)
#define CLUSTER_OFFSET(x) (((x) >> page_cluster) << page_cluster)
--- linux/mm/highmem.c.orig Tue Sep 25 09:29:49 2001
+++ linux/mm/highmem.c Tue Sep 25 10:21:14 2001
@@ -32,7 +32,8 @@
*/
static int pkmap_count[LAST_PKMAP];
static unsigned int last_pkmap_nr;
-static spinlock_t kmap_lock = SPIN_LOCK_UNLOCKED;
+static spinlock_cacheline_t kmap_lock_cacheline = {SPIN_LOCK_UNLOCKED};
+#define kmap_lock kmap_lock_cacheline.lock

pte_t * pkmap_page_table;
-
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