[PATCH] VM statistics code

[PATCH] VM statistics code

[Marcelo Tosatti]

Hi Linus,

The following patch adds detailed VM statistics (reported via /proc/stats)
which is tunable on/off by the CONFIG_VM_STATS option.

There is a modified vmstat.c which is able to read the information
(URL/documentation about it is in the patch).

With this data we are able to know more about what is really going on in
the VM.


Please apply.


diff -Nur --exclude-from=exclude linux.orig/Documentation/Configure.help linux/Documentation/Configure.help
--- linux.orig/Documentation/Configure.help	Wed Jul 11 00:44:55 2001
+++ linux/Documentation/Configure.help	Fri Jul 13 00:59:41 2001
@@ -15656,6 +15656,14 @@
   keys are documented in Documentation/sysrq.txt. Don't say Y unless
   you really know what this hack does.
 
+VM statistics support
+CONFIG_VM_STATS
+  If you say Y here, the kernel will collect detailed information about 
+  the VM subsystem. This information will be available in /proc/stats. 
+  More documentation about this option can be found in 
+  Documentation/vm/statistics.
+  This is only useful for kernel hacking. If unsure, say N. 
+
 ISDN subsystem
 CONFIG_ISDN
   ISDN ("Integrated Services Digital Networks", called RNIS in France)
diff -Nur --exclude-from=exclude linux.orig/Documentation/vm/statistics linux/Documentation/vm/statistics
--- linux.orig/Documentation/vm/statistics	Wed Dec 31 21:00:00 1969
+++ linux/Documentation/vm/statistics	Fri Jul 13 01:04:59 2001
@@ -0,0 +1,46 @@
+
+Description of the additional fields in /proc/stats which are added by the 
+CONFIG_VM_STATS option:
+
+Global statistics:
+
+vm_pglaunder: nr of page_launder() calls 
+vm_pglaunder_write: nr of times page_launder() started writting out data to free 
+memory.
+vm_refill_inactive_scan: nr of refill_inactive_scan() calls
+vm_alloc_resched: nr of reschedule's in __alloc_pages() due to a memory shortage.
+vm_kswapd_wakeup: nr of kswapd wakeup's 
+vm_kreclaimd_wakeup: nr of kreclaimd wakeup's 
+vm_kflushd_wakeup: nr of kflushd wakeup's 
+
+Per-zone statistics:
+free shortage: per-zone free shortage
+inactive shortage: per-zone inactive shortage
+vm_launder_pgscan: number of pages scanned by page_launder
+vm_pgclean: number of pages cleaned (moved to the inactive clean list) by page_launder
+vm_pgskiplocked: number of locked pages skipped by page_launder
+vm_pgskipdirty: number of dirty pages skipped by page_launder
+vm_pglaundered: laundered pages by page_launder
+vm_pgreact: pages reactivated in page_launder
+vm_pgrescue: pages rescue in reclaim_page
+vm_pgagescan: pages scanned by refill_inactive_scan()
+vm_pgagedown: pages aged down by refill_inative_scan()
+vm_pgageup: pages aged up by refill_inactive_scan()/try_to_swap_out()
+vm_pgdeact: deactivated pages by deactivate_page
+vm_pgdeactfail_age: nr of deactivation failures on refill_inactive_scan() 
+due to >0 age
+vm_pgdeactfail_ref: nr of deactivation failures on refill_inactive_scan()
+due to zero aged pages with more users than the pagecache
+vm_reclaimfail: failures of reclaim_page() (no freeable clean pages in the inactive
+clean list for this zone)
+vm_ptescan: nr of present ptes scanned by swap_out()
+vm_pteunmap: nr of present ptes unmapped by swap_out()
+
+There is a modified version of vmstat from procps-2.0.7 at 
+http://bazar.conectiva.com.br/~marcelo/patches/procps/vmstat.c which is able to report
+these fields.
+
+Send questions, comments, etc to the linux-mm mailing list. (linux-mm@kvack.org)
+
+Author: Marcelo Tosatti <marcelo@conectiva.com.br>
+
diff -Nur --exclude-from=exclude linux.orig/arch/i386/config.in linux/arch/i386/config.in
--- linux.orig/arch/i386/config.in	Wed Jul 11 00:44:55 2001
+++ linux/arch/i386/config.in	Fri Jul 13 00:59:41 2001
@@ -388,4 +388,5 @@
 
 #bool 'Debug kmalloc/kfree' CONFIG_DEBUG_MALLOC
 bool 'Magic SysRq key' CONFIG_MAGIC_SYSRQ
+bool 'VM statistics' CONFIG_VM_STATS
 endmenu
diff -Nur --exclude-from=exclude linux.orig/fs/buffer.c linux/fs/buffer.c
--- linux.orig/fs/buffer.c	Wed Jul 11 00:44:53 2001
+++ linux/fs/buffer.c	Fri Jul 13 00:59:08 2001
@@ -45,6 +45,7 @@
 #include <linux/quotaops.h>
 #include <linux/iobuf.h>
 #include <linux/highmem.h>
+#include <linux/mm.h>
 
 #include <asm/uaccess.h>
 #include <asm/io.h>
@@ -2417,6 +2418,7 @@
 			goto cleaned_buffers_try_again;
 		}
 		wakeup_bdflush(0);
+		VM_STAT_INC_KFLUSHD_WAKEUP
 	}
 	return 0;
 }
diff -Nur --exclude-from=exclude linux.orig/fs/proc/proc_misc.c linux/fs/proc/proc_misc.c
--- linux.orig/fs/proc/proc_misc.c	Wed Jul 11 00:44:53 2001
+++ linux/fs/proc/proc_misc.c	Fri Jul 13 00:59:08 2001
@@ -27,6 +27,7 @@
 #include <linux/ioport.h>
 #include <linux/config.h>
 #include <linux/mm.h>
+#include <linux/mmzone.h>
 #include <linux/pagemap.h>
 #include <linux/swap.h>
 #include <linux/slab.h>
@@ -335,6 +336,25 @@
 		kstat.context_swtch,
 		xtime.tv_sec - jif / HZ,
 		total_forks);
+#ifdef CONFIG_VM_STATS
+	len += sprintf(page + len,
+		       	"vm_pglaunder %u\n"
+			"vm_pglaunder_write %u\n"
+			"vm_refill_inactive_scan %u\n"
+			"vm_alloc_resched %u\n"
+			"vm_kswapd_wakeup %u\n"
+			"vm_kreclaimd_wakeup %u\n"
+			"vm_kflushd_wakeup %u\n", 
+			kstat.vm_pglaunder,
+			kstat.vm_pglaunder_write,
+			kstat.vm_refill_inactive_scan,
+			kstat.vm_alloc_resched,
+			kstat.vm_kswapd_wakeup,
+			kstat.vm_kreclaimd_wakeup,
+			kstat.vm_kflushd_wakeup);
+				
+	len = get_perzone_vm_stats(page, len);
+#endif
 
 	return proc_calc_metrics(page, start, off, count, eof, len);
 }
diff -Nur --exclude-from=exclude linux.orig/include/linux/kernel_stat.h linux/include/linux/kernel_stat.h
--- linux.orig/include/linux/kernel_stat.h	Wed Jul 11 00:44:53 2001
+++ linux/include/linux/kernel_stat.h	Fri Jul 13 00:59:08 2001
@@ -33,6 +33,15 @@
 	unsigned int ierrors, oerrors;
 	unsigned int collisions;
 	unsigned int context_swtch;
+#ifdef CONFIG_VM_STATS
+	unsigned int vm_pglaunder;
+	unsigned int vm_pglaunder_write;
+	unsigned int vm_refill_inactive_scan;
+	unsigned int vm_alloc_resched;
+	unsigned int vm_kswapd_wakeup;
+	unsigned int vm_kreclaimd_wakeup;
+	unsigned int vm_kflushd_wakeup;
+#endif
 };
 
 extern struct kernel_stat kstat;
@@ -50,6 +59,30 @@
 
 	return sum;
 }
+#endif
+#ifdef CONFIG_VM_STATS
+/*
+ * Information about these fields can be found at Documentation/vm/statistics
+ * If you change _anything_ here please update the documentation.
+ */
+struct vm_zone_stat {
+	unsigned int vm_launder_pgscan;
+	unsigned int vm_pgclean;
+	unsigned int vm_pgskiplocked;
+	unsigned int vm_pgskipdirty;
+	unsigned int vm_pglaundered;
+	unsigned int vm_pgreact;
+	unsigned int vm_pgrescue; 
+	unsigned int vm_pgagescan;
+	unsigned int vm_pgagedown;
+	unsigned int vm_pgageup;
+	unsigned int vm_pgdeact; 
+	unsigned int vm_pgdeactfail_age;
+	unsigned int vm_pgdeactfail_ref;
+	unsigned int vm_reclaimfail;
+	unsigned int vm_ptescan;
+	unsigned int vm_pteunmap;
+};
 #endif
 
 #endif /* _LINUX_KERNEL_STAT_H */
diff -Nur --exclude-from=exclude linux.orig/include/linux/mm.h linux/include/linux/mm.h
--- linux.orig/include/linux/mm.h	Wed Jul 11 00:44:53 2001
+++ linux/include/linux/mm.h	Fri Jul 13 00:59:08 2001
@@ -591,6 +591,66 @@
 
 extern struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr);
 
+#ifdef CONFIG_VM_STATS
+
+/* Global statistics */
+#define VM_STAT_INC_PGLAUNDER kstat.vm_pglaunder++;
+#define VM_STAT_INC_PGLAUNDER_WRITE kstat.vm_pglaunder_write++;
+#define VM_STAT_INC_REFILL_INACTIVE_SCAN kstat.vm_refill_inactive_scan++;
+#define VM_STAT_INC_ALLOC_RESCHED kstat.vm_alloc_resched++;
+#define VM_STAT_INC_KSWAPD_WAKEUP kstat.vm_kswapd_wakeup++;
+#define VM_STAT_INC_KRECLAIMD_WAKEUP kstat.vm_kreclaimd_wakeup++;
+#define VM_STAT_INC_KFLUSHD_WAKEUP kstat.vm_kflushd_wakeup++;
+
+/* Per-zone statistics */ 
+
+#define VM_STAT_INC_PGSCAN(zone) zone->stat.vm_launder_pgscan++;
+#define VM_STAT_INC_PGCLEAN(zone) zone->stat.vm_pgclean++;
+#define VM_STAT_INC_PGSKIPLOCKED(zone) zone->stat.vm_pgskiplocked++;
+#define VM_STAT_INC_PGSKIPDIRTY(zone) zone->stat.vm_pgskipdirty++;
+#define VM_STAT_INC_PGLAUNDERED(zone) zone->stat.vm_pglaundered++;
+#define VM_STAT_INC_PGREACT(zone) zone->stat.vm_pgreact++;
+#define VM_STAT_INC_PGRESCUE(zone) zone->stat.vm_pgrescue++;
+#define VM_STAT_INC_PGAGESCAN(zone) zone->stat.vm_pgagescan++;
+#define VM_STAT_INC_PGAGEDOWN(zone) zone->stat.vm_pgagedown++;
+#define VM_STAT_INC_PGAGEUP(zone) zone->stat.vm_pgageup++;
+#define VM_STAT_INC_PGDEACT(zone) zone->stat.vm_pgdeact++;
+#define VM_STAT_INC_PGDEACTFAIL_AGE(zone) zone->stat.vm_pgdeactfail_age++;
+#define VM_STAT_INC_PGDEACTFAIL_REF(zone) zone->stat.vm_pgdeactfail_ref++;
+#define VM_STAT_INC_RECLAIMFAIL(zone) zone->stat.vm_reclaimfail++;
+#define VM_STAT_INC_PTESCAN(zone) zone->stat.vm_ptescan++;
+#define VM_STAT_INC_PTEUNMAP(zone) zone->stat.vm_pteunmap++;
+
+#else
+#define VM_STAT_INC_PGLAUNDER do { } while (0);
+#define VM_STAT_INC_PGLAUNDER_WRITE do { } while (0);
+#define VM_STAT_INC_REFILL_INACTIVE_SCAN do { } while (0);
+#define VM_STAT_INC_ALLOC_RESCHED do { } while (0);
+#define VM_STAT_INC_KSWAPD_WAKEUP do { } while (0);
+#define VM_STAT_INC_KRECLAIMD_WAKEUP do { } while (0);
+#define VM_STAT_INC_KFLUSHD_WAKEUP do { } while (0);
+
+#define VM_STAT_INC_PGSCAN(zone) do { } while (0);
+#define VM_STAT_INC_PGCLEAN(zone)  do { } while (0);
+#define VM_STAT_INC_PGSKIPLOCKED(zone) do { } while (0);
+#define VM_STAT_INC_PGSKIPDIRTY(zone) do { } while (0);
+#define VM_STAT_INC_PGLAUNDERED(zone) do { } while (0);
+#define VM_STAT_INC_PGREACT(zone) do { } while (0);
+#define VM_STAT_INC_PGRESCUE(zone) do { } while (0);
+#define VM_STAT_INC_PGDEACT(zone) do { } while (0);
+#define VM_STAT_INC_PGAGESCAN(zone) do { } while (0);
+#define VM_STAT_INC_PGAGEDOWN(zone) do { } while (0);
+#define VM_STAT_INC_PGAGEUP(zone) do { } while (0);
+#define VM_STAT_INC_PGDEACT(zone) do { } while (0);
+#define VM_STAT_INC_PGDEACTFAIL_AGE(zone) do { } while (0);
+#define VM_STAT_INC_PGDEACTFAIL_REF(zone) do { } while (0);
+#define VM_STAT_INC_RECLAIMFAIL(zone) do { } while (0);
+#define VM_STAT_INC_PTESCAN(zone) do { } while (0);
+#define VM_STAT_INC_PTEUNMAP(zone) do { } while (0);
+
+
+#endif
+
 #endif /* __KERNEL__ */
 
 #endif
diff -Nur --exclude-from=exclude linux.orig/include/linux/mmzone.h linux/include/linux/mmzone.h
--- linux.orig/include/linux/mmzone.h	Wed Jul 11 00:44:53 2001
+++ linux/include/linux/mmzone.h	Fri Jul 13 00:59:08 2001
@@ -7,6 +7,7 @@
 #include <linux/config.h>
 #include <linux/spinlock.h>
 #include <linux/list.h>
+#include <linux/kernel_stat.h>
 
 /*
  * Free memory management - zoned buddy allocator.
@@ -58,6 +59,9 @@
 	 */
 	char			*name;
 	unsigned long		size;
+#ifdef CONFIG_VM_STATS
+	struct vm_zone_stat stat;
+#endif
 } zone_t;
 
 #define ZONE_DMA		0
@@ -122,8 +126,12 @@
 extern void free_area_init_core(int nid, pg_data_t *pgdat, struct page **gmap,
   unsigned long *zones_size, unsigned long paddr, unsigned long *zholes_size,
   struct page *pmap);
+#ifdef CONFIG_VM_STATS
+extern int get_perzone_vm_stats(char *page, int len);
+#endif
 
 extern pg_data_t contig_page_data;
+
 
 #ifndef CONFIG_DISCONTIGMEM
 
diff -Nur --exclude-from=exclude linux.orig/include/linux/swap.h linux/include/linux/swap.h
--- linux.orig/include/linux/swap.h	Wed Jul 11 00:44:53 2001
+++ linux/include/linux/swap.h	Fri Jul 13 00:59:08 2001
@@ -125,6 +125,33 @@
 extern void wakeup_kswapd(void);
 extern int try_to_free_pages(unsigned int gfp_mask);
 
+#ifdef CONFIG_VM_STATS
+static inline int zone_free_shortage(zone_t *zone) 
+{
+	int sum = 0;
+	if (zone->inactive_clean_pages + zone->free_pages
+			< zone->pages_min) {
+		sum += zone->pages_min;
+		sum -= zone->free_pages;
+		sum -= zone->inactive_clean_pages;
+	}
+	return sum;
+}
+
+static inline int zone_inactive_shortage(zone_t *zone)
+{
+	int sum;
+
+	sum = zone->pages_high;
+	sum -= zone->inactive_dirty_pages; 
+	sum -= zone->inactive_clean_pages;
+	sum -= zone->free_pages;
+	
+	return (sum > 0 ? sum : 0);
+}
+#endif
+
+
 /* linux/mm/page_io.c */
 extern void rw_swap_page(int, struct page *);
 extern void rw_swap_page_nolock(int, swp_entry_t, char *);
diff -Nur --exclude-from=exclude linux.orig/mm/page_alloc.c linux/mm/page_alloc.c
--- linux.orig/mm/page_alloc.c	Wed Jul 11 00:44:53 2001
+++ linux/mm/page_alloc.c	Fri Jul 13 00:59:08 2001
@@ -326,6 +326,7 @@
 				return page;
 		} else if (z->free_pages < z->pages_min &&
 					waitqueue_active(&kreclaimd_wait)) {
+				VM_STAT_INC_KRECLAIMD_WAKEUP
 				wake_up_interruptible(&kreclaimd_wait);
 		}
 	}
@@ -373,6 +374,7 @@
 	 */
 	wakeup_kswapd();
 	if (gfp_mask & __GFP_WAIT) {
+		VM_STAT_INC_ALLOC_RESCHED
 		__set_current_state(TASK_RUNNING);
 		current->policy |= SCHED_YIELD;
 		schedule();
@@ -619,6 +621,69 @@
 		pgdat = pgdat->node_next;
 	}
 	return pages;
+}
+#endif
+
+#ifdef CONFIG_VM_STATS
+int get_perzone_vm_stats (char *page, int len)
+{
+	unsigned type;	
+	int llen;
+	unsigned long flags;
+	pg_data_t *pgdat = pgdat_list;
+
+	llen = len;
+
+	for (type = 0; type < MAX_NR_ZONES; type++) {
+		zone_t *zone = pgdat->node_zones + type;
+		if (!zone->size)
+			break;
+
+
+		llen += sprintf(page + llen, "Zone: %s\n", zone->name);
+
+		llen += sprintf(page + llen, 
+				"free shortage: %u\n"
+				"inactive shortage: %u\n",
+				zone_free_shortage(zone),
+				zone_inactive_shortage(zone));
+
+		llen += sprintf(page + llen,
+			"vm_launder_pgscan %u\n"
+			"vm_pgclean %u\n"
+			"vm_pgskiplocked %u\n"
+			"vm_pgskipdirty %u\n"
+			"vm_pglaundered %u\n"
+			"vm_pgreact %u\n"
+			"vm_pgrescue %u\n"
+			"vm_pgagescan %u\n"
+			"vm_pgagedown %u\n"
+			"vm_pgageup %u\n"
+			"vm_pgdeact %u\n"
+			"vm_pgdeactfail_age %u\n"
+			"vm_pgdeactfail_ref %u\n"
+			"vm_reclaimfail %u\n"
+			"vm_ptescan %u\n"
+			"vm_pteunmap %u\n",
+			zone->stat.vm_launder_pgscan,
+			zone->stat.vm_pgclean,
+			zone->stat.vm_pgskiplocked, 
+			zone->stat.vm_pgskipdirty,
+			zone->stat.vm_pglaundered,
+			zone->stat.vm_pgreact, 
+			zone->stat.vm_pgrescue,
+			zone->stat.vm_pgagescan,
+			zone->stat.vm_pgagedown,
+			zone->stat.vm_pgageup,
+			zone->stat.vm_pgdeact,
+			zone->stat.vm_pgdeactfail_age,
+			zone->stat.vm_pgdeactfail_ref,
+			zone->stat.vm_reclaimfail,
+			zone->stat.vm_ptescan,
+			zone->stat.vm_pteunmap);
+	}
+
+	return llen;
 }
 #endif
 
diff -Nur --exclude-from=exclude linux.orig/mm/vmscan.c linux/mm/vmscan.c
--- linux.orig/mm/vmscan.c	Wed Jul 11 00:44:53 2001
+++ linux/mm/vmscan.c	Fri Jul 13 00:59:08 2001
@@ -41,11 +41,14 @@
 	pte_t pte;
 	swp_entry_t entry;
 
+	VM_STAT_INC_PTESCAN(page->zone)
+
 	/* Don't look at this pte if it's been accessed recently. */
 	if (ptep_test_and_clear_young(page_table)) {
 		page->age += PAGE_AGE_ADV;
 		if (page->age > PAGE_AGE_MAX)
 			page->age = PAGE_AGE_MAX;
+		VM_STAT_INC_PGAGEUP(page->zone)
 		return;
 	}
 
@@ -73,6 +76,7 @@
 		swap_duplicate(entry);
 		set_pte(page_table, swp_entry_to_pte(entry));
 drop_pte:
+		VM_STAT_INC_PTEUNMAP(page->zone)
 		mm->rss--;
 		if (!page->age)
 			deactivate_page(page);
@@ -359,6 +363,7 @@
 				(!page->buffers && page_count(page) > 1)) {
 			del_page_from_inactive_clean_list(page);
 			add_page_to_active_list(page);
+			VM_STAT_INC_PGRESCUE(page->zone)
 			continue;
 		}
 
@@ -388,6 +393,7 @@
 	}
 	/* Reset page pointer, maybe we encountered an unfreeable page. */
 	page = NULL;
+	VM_STAT_INC_RECLAIMFAIL(zone)
 	goto out;
 
 found_page:
@@ -436,6 +442,8 @@
 	maxlaunder = 0;
 	cleaned_pages = 0;
 
+	VM_STAT_INC_PGLAUNDER
+
 dirty_page_rescan:
 	spin_lock(&pagemap_lru_lock);
 	maxscan = nr_inactive_dirty_pages;
@@ -452,12 +460,15 @@
 			continue;
 		}
 
+		VM_STAT_INC_PGSCAN(page->zone)
+
 		/* Page is or was in use?  Move it to the active list. */
 		if (PageReferenced(page) || page->age > 0 ||
 				(!page->buffers && page_count(page) > 1) ||
 				page_ramdisk(page)) {
 			del_page_from_inactive_dirty_list(page);
 			add_page_to_active_list(page);
+			VM_STAT_INC_PGREACT(page->zone)
 			continue;
 		}
 
@@ -468,6 +479,7 @@
 		if (TryLockPage(page)) {
 			list_del(page_lru);
 			list_add(page_lru, &inactive_dirty_list);
+			VM_STAT_INC_PGSKIPLOCKED(page->zone)
 			continue;
 		}
 
@@ -485,6 +497,7 @@
 			if (!launder_loop || !CAN_DO_FS) {
 				list_del(page_lru);
 				list_add(page_lru, &inactive_dirty_list);
+				VM_STAT_INC_PGSKIPDIRTY(page->zone)
 				UnlockPage(page);
 				continue;
 			}
@@ -497,6 +510,8 @@
 			writepage(page);
 			page_cache_release(page);
 
+			VM_STAT_INC_PGLAUNDERED(page->zone)
+
 			/* And re-start the thing.. */
 			spin_lock(&pagemap_lru_lock);
 			continue;
@@ -525,12 +540,18 @@
 			spin_unlock(&pagemap_lru_lock);
 
 			/* Will we do (asynchronous) IO? */
-			if (launder_loop && maxlaunder == 0 && sync)
-				buffer_mask = gfp_mask;				/* Do as much as we can */
-			else if (launder_loop && maxlaunder-- > 0)
-				buffer_mask = gfp_mask & ~__GFP_WAIT;			/* Don't wait, async write-out */
+			if (launder_loop && maxlaunder == 0 && sync) {
+				buffer_mask = gfp_mask;		
+				VM_STAT_INC_PGLAUNDERED(page->zone)
+				/* Do as much as we can */
+			} else if (launder_loop && maxlaunder-- > 0) {
+				buffer_mask = gfp_mask & ~__GFP_WAIT;	
+				VM_STAT_INC_PGLAUNDERED(page->zone)
+				/* Don't wait, async write-out */
+			}
 			else
-				buffer_mask = gfp_mask & ~(__GFP_WAIT | __GFP_IO);	/* Don't even start IO */
+				buffer_mask = gfp_mask & ~(__GFP_WAIT | __GFP_IO);
+				/* Don't even start IO */
 
 			/* Try to free the page buffers. */
 			clearedbuf = try_to_free_buffers(page, buffer_mask);
@@ -559,6 +580,7 @@
 			/* OK, we "created" a freeable page. */
 			} else /* page->mapping && page_count(page) == 2 */ {
 				add_page_to_inactive_clean_list(page);
+				VM_STAT_INC_PGCLEAN(page->zone)
 				cleaned_pages++;
 			}
 
@@ -587,6 +609,7 @@
 			del_page_from_inactive_dirty_list(page);
 			add_page_to_inactive_clean_list(page);
 			UnlockPage(page);
+			VM_STAT_INC_PGCLEAN(page->zone)
 			cleaned_pages++;
 		} else {
 page_active:
@@ -622,6 +645,7 @@
 		maxlaunder = MAX_LAUNDER;
 		/* Kflushd takes care of the rest. */
 		wakeup_bdflush(0);
+		VM_STAT_INC_PGLAUNDER_WRITE
 		goto dirty_page_rescan;
 	}
 
@@ -645,6 +669,8 @@
 	int page_active = 0;
 	int nr_deactivated = 0;
 
+	VM_STAT_INC_REFILL_INACTIVE_SCAN
+
 	/*
 	 * When we are background aging, we try to increase the page aging
 	 * information in the system.
@@ -652,6 +678,7 @@
 	if (!target)
 		maxscan = nr_active_pages >> 4;
 
+
 	/* Take the lock while messing with the list... */
 	spin_lock(&pagemap_lru_lock);
 	while (maxscan-- > 0 && (page_lru = active_list.prev) != &active_list) {
@@ -665,12 +692,16 @@
 			continue;
 		}
 
+		VM_STAT_INC_PGAGESCAN(page->zone)
+
 		/* Do aging on the pages. */
 		if (PageTestandClearReferenced(page)) {
 			age_page_up_nolock(page);
 			page_active = 1;
+			VM_STAT_INC_PGAGEUP(page->zone)
 		} else {
 			age_page_down_ageonly(page);
+			VM_STAT_INC_PGAGEDOWN(page->zone)
 			/*
 			 * Since we don't hold a reference on the page
 			 * ourselves, we have to do our test a bit more
@@ -697,7 +728,21 @@
 		if (page_active || PageActive(page)) {
 			list_del(page_lru);
 			list_add(page_lru, &active_list);
+#ifdef CONFIG_VM_STATS
+			/*
+			 * The page deactivation can fail due to a page
+			 * with non zero age (accounted as DEACTFAIL_AGE) 
+			 * or due to a zero aged page with more users than 
+			 * the pagecache. (accounted as DEACTFAIL_REF)
+			 */
+			if (page->age)
+				VM_STAT_INC_PGDEACTFAIL_AGE(page->zone)
+			else
+				VM_STAT_INC_PGDEACTFAIL_REF(page->zone)
+#endif
+
 		} else {
+			VM_STAT_INC_PGDEACT(page->zone)
 			nr_deactivated++;
 			if (target && nr_deactivated >= target)
 				break;
@@ -963,8 +1008,10 @@
 
 void wakeup_kswapd(void)
 {
-	if (waitqueue_active(&kswapd_wait))
+	if (waitqueue_active(&kswapd_wait)) {
 		wake_up_interruptible(&kswapd_wait);
+		VM_STAT_INC_KSWAPD_WAKEUP
+	}
 }
 
 /*

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Re: [PATCH] VM statistics code

[Chris Wedgwood]

On Fri, Jul 13, 2001 at 07:08:23PM -0300, Marcelo Tosatti wrote:

    With this data we are able to know more about what is really going
    on in the VM.

    +vm_pglaunder: nr of page_launder() calls 
    +vm_pglaunder_write: nr of times page_launder() started writting out data to free 
    +memory.
    +vm_refill_inactive_scan: nr of refill_inactive_scan() calls
    +vm_alloc_resched: nr of reschedule's in __alloc_pages() due to a memory shortage.
    +vm_kswapd_wakeup: nr of kswapd wakeup's 
    +vm_kreclaimd_wakeup: nr of kreclaimd wakeup's 
    +vm_kflushd_wakeup: nr of kflushd wakeup's 
    +
    +Per-zone statistics:
    +free shortage: per-zone free shortage
    +inactive shortage: per-zone inactive shortage
    +vm_launder_pgscan: number of pages scanned by page_launder
    +vm_pgclean: number of pages cleaned (moved to the inactive clean list) by page_launder
    +vm_pgskiplocked: number of locked pages skipped by page_launder
    +vm_pgskipdirty: number of dirty pages skipped by page_launder
    +vm_pglaundered: laundered pages by page_launder
    +vm_pgreact: pages reactivated in page_launder
    +vm_pgrescue: pages rescue in reclaim_page
    +vm_pgagescan: pages scanned by refill_inactive_scan()
    +vm_pgagedown: pages aged down by refill_inative_scan()
    +vm_pgageup: pages aged up by refill_inactive_scan()/try_to_swap_out()
    +vm_pgdeact: deactivated pages by deactivate_page
    +vm_pgdeactfail_age: nr of deactivation failures on refill_inactive_scan() 
    +due to >0 age
    +vm_pgdeactfail_ref: nr of deactivation failures on refill_inactive_scan()
    +due to zero aged pages with more users than the pagecache
    +vm_reclaimfail: failures of reclaim_page() (no freeable clean pages in the inactive
    +clean list for this zone)
    +vm_ptescan: nr of present ptes scanned by swap_out()
    +vm_pteunmap: nr of present ptes unmapped by swap_out()

Some of these seem very specialised and low-level.

Perhaps another /proc entry might be a better idea along with either a
different vmstat, or changes to vmstat such that it will behave as
always if not given a magic command line switch and/or this new /proc
entry isn't present?

Right now, much of what comes form vmstat vaguley resembles other OSs,
with the above, it will be very different.



   --cw

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Re: [PATCH] VM statistics code

[Marcelo Tosatti]

On Sat, 14 Jul 2001, Chris Wedgwood wrote:

> On Fri, Jul 13, 2001 at 07:08:23PM -0300, Marcelo Tosatti wrote:
> 
>     With this data we are able to know more about what is really going
>     on in the VM.
> 
>     +vm_pglaunder: nr of page_launder() calls 
>     +vm_pglaunder_write: nr of times page_launder() started writting out data to free 
>     +memory.
>     +vm_refill_inactive_scan: nr of refill_inactive_scan() calls
>     +vm_alloc_resched: nr of reschedule's in __alloc_pages() due to a memory shortage.
>     +vm_kswapd_wakeup: nr of kswapd wakeup's 
>     +vm_kreclaimd_wakeup: nr of kreclaimd wakeup's 
>     +vm_kflushd_wakeup: nr of kflushd wakeup's 
>     +
>     +Per-zone statistics:
>     +free shortage: per-zone free shortage
>     +inactive shortage: per-zone inactive shortage
>     +vm_launder_pgscan: number of pages scanned by page_launder
>     +vm_pgclean: number of pages cleaned (moved to the inactive clean list) by page_launder
>     +vm_pgskiplocked: number of locked pages skipped by page_launder
>     +vm_pgskipdirty: number of dirty pages skipped by page_launder
>     +vm_pglaundered: laundered pages by page_launder
>     +vm_pgreact: pages reactivated in page_launder
>     +vm_pgrescue: pages rescue in reclaim_page
>     +vm_pgagescan: pages scanned by refill_inactive_scan()
>     +vm_pgagedown: pages aged down by refill_inative_scan()
>     +vm_pgageup: pages aged up by refill_inactive_scan()/try_to_swap_out()
>     +vm_pgdeact: deactivated pages by deactivate_page
>     +vm_pgdeactfail_age: nr of deactivation failures on refill_inactive_scan() 
>     +due to >0 age
>     +vm_pgdeactfail_ref: nr of deactivation failures on refill_inactive_scan()
>     +due to zero aged pages with more users than the pagecache
>     +vm_reclaimfail: failures of reclaim_page() (no freeable clean pages in the inactive
>     +clean list for this zone)
>     +vm_ptescan: nr of present ptes scanned by swap_out()
>     +vm_pteunmap: nr of present ptes unmapped by swap_out()
> 
> Some of these seem very specialised and low-level.

Yes they are.

> Perhaps another /proc entry might be a better idea along with either a
> different vmstat, 

Maybe. Personally I don't really care about the way we are doing this, as
long as I can get the information. I can add /proc/vmstat easily if
needed...

Linus, how do you want this thing done to be accepted in the stock tree? 

> or changes to vmstat such that it will behave as always if not given a
> magic command line switch and/or this new /proc entry isn't present?

Well, I don't want to include this stuff on the stock vmstat code right
now. I've done an ugly hack in vmstat.c to get the thing to work and thats
it.

I will keep an updated version of the "hacked" vmstat.c on my homepage
until I find time/balls to code something which does not stink. 

> Right now, much of what comes form vmstat vaguley resembles other OSs,
> with the above, it will be very different.

Indeed.

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Re: [PATCH] VM statistics code

[Chris Wedgwood]

On Fri, Jul 13, 2001 at 07:53:12PM -0300, Marcelo Tosatti wrote:

    Maybe. Personally I don't really care about the way we are doing
    this, as long as I can get the information. I can add /proc/vmstat
    easily if needed...

How about something under advance kernel hacking options of wherever
the sysrq options is? (and profiling used to live, before it was
always there), or, since the code is rather small, we could perhaps
always have this available.

    Well, I don't want to include this stuff on the stock vmstat code
    right now. I've done an ugly hack in vmstat.c to get the thing to
    work and thats it.

Fair enough, but the comment "please apply" makes me nervous then :)



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Re: [PATCH] VM statistics code

[Marcelo Tosatti]

On Sat, 14 Jul 2001, Chris Wedgwood wrote:

> On Fri, Jul 13, 2001 at 07:53:12PM -0300, Marcelo Tosatti wrote:
> 
>     Maybe. Personally I don't really care about the way we are doing
>     this, as long as I can get the information. I can add /proc/vmstat
>     easily if needed...
> 
> How about something under advance kernel hacking options of wherever
> the sysrq options is? (and profiling used to live, before it was
> always there), or, since the code is rather small, we could perhaps
> always have this available.

Well, it is already under "kernel hacking". 

I guess you missed it, right ? 

+VM statistics support
+CONFIG_VM_STATS
+  If you say Y here, the kernel will collect detailed information about 
+  the VM subsystem. This information will be available in /proc/stats. 
+  More documentation about this option can be found in 
+  Documentation/vm/statistics.
+  This is only useful for kernel hacking. If unsure, say N. 
+

Obviously we want this disabled by default.

>     Well, I don't want to include this stuff on the stock vmstat code
>     right now. I've done an ugly hack in vmstat.c to get the thing to
>     work and thats it.
> 
> Fair enough, but the comment "please apply" makes me nervous then :)

As I said, I'll keep an uptodated version of vmstat.c in my homepage for
the people who want to use it. Right now I don't the time to make a new
nice tool.


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Re: [PATCH] VM statistics code

[David S. Miller]

Chris Wedgwood writes:
 > On Fri, Jul 13, 2001 at 07:53:12PM -0300, Marcelo Tosatti wrote:
 > 
 >     Maybe. Personally I don't really care about the way we are doing
 >     this, as long as I can get the information. I can add /proc/vmstat
 >     easily if needed...
 > 
 > How about something under advance kernel hacking options of wherever
 > the sysrq options is? (and profiling used to live, before it was
 > always there), or, since the code is rather small, we could perhaps
 > always have this available.

I personally feel that it is imperative to have some kind of "lower
level" statistics available by default in the VM.  It would
undoubtedly save some head scratching for most bug reports.

We have all of this kind of stuff in the networking, because the SNMP
mibs require us to keep track of the information.  I can say for
certain that several bugs were found quickly because we were able to
notice anomalies in the events being triggered on the person's
machine.

There is a bit of a performance issue, since our VM is decently
threaded.  That can be solved with per-cpu statistics blocks like
the networking uses.

Later,
David S. Miller
davem@redhat.com
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Re: [PATCH] VM statistics code

[Andrew Morton]

Marcelo Tosatti wrote:
> 
> Hi Linus,
> 
> The following patch adds detailed VM statistics (reported via /proc/stats)
> which is tunable on/off by the CONFIG_VM_STATS option.

We need this, bad.  Two suggested changes:

>
> +#define VM_STAT_INC_PTEUNMAP(zone) zone->stat.vm_pteunmap++;

All these macros are a waste of space :)

Much better to have:

#define VM_STAT_ZONE(zone, op)	zone->stat.op

Then, at the call site:

	VM_STAT_ZONE(some_zone, vm_pteunmap++);

Or, if you prefer,

#define VM_STAT_ZONE_INC(zone, field)	zone->field++

That way, you don't have to add a new macro each time
you add a new field.



Also, a sysrq key which dumps the stats out, please - when
your box has wedged there ain't no way you'll be running
vmstat.

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Re: [PATCH] VM statistics code

[Marcelo Tosatti]

On Sat, 14 Jul 2001, Andrew Morton wrote:

> Marcelo Tosatti wrote:
> > 
> > Hi Linus,
> > 
> > The following patch adds detailed VM statistics (reported via /proc/stats)
> > which is tunable on/off by the CONFIG_VM_STATS option.
> 
> We need this, bad.  Two suggested changes:
> 
> >
> > +#define VM_STAT_INC_PTEUNMAP(zone) zone->stat.vm_pteunmap++;
> 
> All these macros are a waste of space :)
> 
> Much better to have:
> 
> #define VM_STAT_ZONE(zone, op)	zone->stat.op
> 
> Then, at the call site:
> 
> 	VM_STAT_ZONE(some_zone, vm_pteunmap++);
> 
> Or, if you prefer,
> 
> #define VM_STAT_ZONE_INC(zone, field)	zone->field++
> 
> That way, you don't have to add a new macro each time
> you add a new field.

You're right. Will do that.

> Also, a sysrq key which dumps the stats out, please - when
> your box has wedged there ain't no way you'll be running
> vmstat.

Agreed. 

Thanks for your comments. 

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