[XFS] Re-work pagebuf & xfs stats to use per-cpu variables -

big globals that are written all the time

SGI Modid: 2.5.x-xfs:slinx:159069a

fs/xfs/linux/xfs_stats.c

@@ -33,7 +33,7 @@
 #include "xfs.h"
 #include <linux/proc_fs.h>
 
-struct xfsstats xfsstats;
+DEFINE_PER_CPU(struct xfsstats, xfsstats);
 
 STATIC int
 xfs_read_xfsstats(
@@ -44,7 +44,11 @@ xfs_read_xfsstats(
 	int		*eof,
 	void		*data)
 {
-	int		i, j, len;
+	int		c, i, j, len, val;
+	__uint64_t	xs_xstrat_bytes = 0;
+	__uint64_t	xs_write_bytes = 0;
+	__uint64_t	xs_read_bytes = 0;
+
 	static struct xstats_entry {
 		char	*desc;
 		int	endpoint;
@@ -65,21 +69,32 @@ xfs_read_xfsstats(
 		{ "vnodes",		XFSSTAT_END_VNODE_OPS		},
 	};
 
+	/* Loop over all stats groups */
 	for (i=j=len = 0; i < sizeof(xstats)/sizeof(struct xstats_entry); i++) {
 		len += sprintf(buffer + len, xstats[i].desc);
 		/* inner loop does each group */
 		while (j < xstats[i].endpoint) {
-			len += sprintf(buffer + len, " %u",
-					*(((__u32*)&xfsstats) + j));
+			val = 0;
+			/* sum over all cpus */
+			for (c = 0; c < NR_CPUS; c++) {
+				if (!cpu_possible(c)) continue;
+				val += *(((__u32*)&per_cpu(xfsstats, c) + j));
+			}
+			len += sprintf(buffer + len, " %u", val);
 			j++;
 		}
 		buffer[len++] = '\n';
 	}
 	/* extra precision counters */
+	for (i = 0; i < NR_CPUS; i++) {
+		if (!cpu_possible(i)) continue;
+		xs_xstrat_bytes += per_cpu(xfsstats, i).xs_xstrat_bytes;
+		xs_write_bytes += per_cpu(xfsstats, i).xs_write_bytes;
+		xs_read_bytes += per_cpu(xfsstats, i).xs_read_bytes;
+	}
+
 	len += sprintf(buffer + len, "xpc %Lu %Lu %Lu\n",
-			xfsstats.xs_xstrat_bytes,
-			xfsstats.xs_write_bytes,
-			xfsstats.xs_read_bytes);
+			xs_xstrat_bytes, xs_write_bytes, xs_read_bytes);
 	len += sprintf(buffer + len, "debug %u\n",
 #if defined(XFSDEBUG)
 		1);

fs/xfs/linux/xfs_stats.h

@@ -35,6 +35,8 @@
 
 #if defined(CONFIG_PROC_FS) && !defined(XFS_STATS_OFF)
 
+#include <linux/percpu.h>
+
 /*
  * XFS global statistics
  */
@@ -126,11 +128,11 @@ struct xfsstats {
 	__uint64_t		xs_read_bytes;
 };
 
-extern struct xfsstats xfsstats;
+DECLARE_PER_CPU(struct xfsstats, xfsstats);
 
-# define XFS_STATS_INC(count)		( xfsstats.count++ )
-# define XFS_STATS_DEC(count)		( xfsstats.count-- )
-# define XFS_STATS_ADD(count, inc)	( xfsstats.count += (inc) )
+# define XFS_STATS_INC(count)		( get_cpu_var(xfsstats).count++ )
+# define XFS_STATS_DEC(count)		( get_cpu_var(xfsstats).count-- )
+# define XFS_STATS_ADD(count, inc)	( get_cpu_var(xfsstats).count += (inc) )
 
 extern void xfs_init_procfs(void);
 extern void xfs_cleanup_procfs(void);

fs/xfs/linux/xfs_sysctl.c

@@ -48,17 +48,23 @@ xfs_stats_clear_proc_handler(
 	void		*buffer,
 	size_t		*lenp)
 {
-	int		ret, *valp = ctl->data;
+	int		c, ret, *valp = ctl->data;
 	__uint32_t	vn_active;
 
 	ret = proc_doulongvec_minmax(ctl, write, filp, buffer, lenp);
 
 	if (!ret && write && *valp) {
 		printk("XFS Clearing xfsstats\n");
-		/* save vn_active, it's a universal truth! */
-		vn_active = xfsstats.vn_active;
-		memset(&xfsstats, 0, sizeof(xfsstats));
-		xfsstats.vn_active = vn_active;
+		for (c = 0; c < NR_CPUS; c++) {
+			if (!cpu_possible(c)) continue;
+			preempt_disable();
+			/* save vn_active, it's a universal truth! */
+			vn_active = per_cpu(xfsstats, c).vn_active;
+			memset(&per_cpu(xfsstats, c), 0,
+			       sizeof(struct xfsstats));
+			per_cpu(xfsstats, c).vn_active = vn_active;
+			preempt_enable();
+		}
 		xfs_stats_clear = 0;
 	}
 

fs/xfs/pagebuf/page_buf.c

@@ -141,7 +141,7 @@ pagebuf_param_t pb_params = {
  * Pagebuf statistics variables
  */
 
-struct pbstats pbstats;
+DEFINE_PER_CPU(struct pbstats, pbstats);
 
 /*
  * Pagebuf allocation / freeing.
@@ -1842,14 +1842,18 @@ pb_stats_clear_handler(
 	void			*buffer,
 	size_t			*lenp)
 {
-	int			ret;
+	int			c, ret;
 	int			*valp = ctl->data;
 
 	ret = proc_doulongvec_minmax(ctl, write, filp, buffer, lenp);
 
 	if (!ret && write && *valp) {
 		printk("XFS Clearing pbstats\n");
-		memset(&pbstats, 0, sizeof(pbstats));
+		for (c = 0; c < NR_CPUS; c++) {
+			if (!cpu_possible(c)) continue;
+				memset(&per_cpu(pbstats, c), 0,
+				       sizeof(struct pbstats));
+		}
 		pb_params.stats_clear.val = 0;
 	}
 
@@ -1903,13 +1907,17 @@ pagebuf_readstats(
 	int			*eof,
 	void			*data)
 {
-	int			i, len;
+	int			c, i, len, val;
 
 	len = 0;
 	len += sprintf(buffer + len, "pagebuf");
-	for (i = 0; i < sizeof(pbstats) / sizeof(u_int32_t); i++) {
-		len += sprintf(buffer + len, " %u",
-			*(((u_int32_t*)&pbstats) + i));
+	for (i = 0; i < sizeof(struct pbstats) / sizeof(u_int32_t); i++) {
+		val = 0;
+		for (c = 0 ; c < NR_CPUS; c++) {
+			if (!cpu_possible(c)) continue;
+			val += *(((u_int32_t*)&per_cpu(pbstats, c) + i));
+		}
+		len += sprintf(buffer + len, " %u", val);
 	}
 	buffer[len++] = '\n';