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Subject[PATCH 5/5] Print out PAGE_OWNER statistics in relation to fragmentation avoidance
Date

When PAGE_OWNER is set, more information is available of relevance
to fragmentation avoidance. A second line is added to /proc/page_owner
showing the PFN, the pageblock number, the mobility type of the page based
on its allocation flags, whether the allocation is improperly placed and
the flags. A sample entry looks like

Page allocated via order 0, mask 0x1280d2
PFN 7355 Block 7 type 3 Fallback Flags LA
[0xc01528c6] __handle_mm_fault+598
[0xc0320427] do_page_fault+279
[0xc031ed9a] error_code+114

This information can be used to identify pages that are improperly placed. As
the format of PAGE_OWNER data is now different, the comment at the top of
Documentation/page_owner.c is updated with new instructions.

As PAGE_OWNER tracks the GFP flags used to allocate the pages,
/proc/pagetypeinfo is enhanced to contain how many mixed blocks exist. The
additional output looks like

Number of mixed blocks Unmovable Reclaimable Movable Reserve
Node 0, zone DMA 0 1 2 1
Node 0, zone Normal 2 11 33 0

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Christoph Lameter <clameter@sgi.com>
---

Documentation/page_owner.c | 3 -
fs/proc/proc_misc.c | 28 ++++++++++++
mm/vmstat.c | 93 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 123 insertions(+), 1 deletion(-)

diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.22-rc2-mm1-005_statistics/Documentation/page_owner.c linux-2.6.22-rc2-mm1-006_statistics_owner/Documentation/page_owner.c
--- linux-2.6.22-rc2-mm1-005_statistics/Documentation/page_owner.c 2007-05-24 10:13:32.000000000 +0100
+++ linux-2.6.22-rc2-mm1-006_statistics_owner/Documentation/page_owner.c 2007-05-24 16:46:57.000000000 +0100
@@ -2,7 +2,8 @@
* User-space helper to sort the output of /proc/page_owner
*
* Example use:
- * cat /proc/page_owner > page_owner.txt
+ * cat /proc/page_owner > page_owner_full.txt
+ * grep -v ^PFN page_owner_full.txt > page_owner.txt
* ./sort page_owner.txt sorted_page_owner.txt
*/

diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.22-rc2-mm1-005_statistics/fs/proc/proc_misc.c linux-2.6.22-rc2-mm1-006_statistics_owner/fs/proc/proc_misc.c
--- linux-2.6.22-rc2-mm1-005_statistics/fs/proc/proc_misc.c 2007-05-24 16:45:22.000000000 +0100
+++ linux-2.6.22-rc2-mm1-006_statistics_owner/fs/proc/proc_misc.c 2007-05-24 16:46:57.000000000 +0100
@@ -761,6 +761,7 @@ read_page_owner(struct file *file, char
unsigned long offset = 0, symsize;
int i;
ssize_t num_written = 0;
+ int blocktype = 0, pagetype = 0;

pfn = min_low_pfn + *ppos;
page = pfn_to_page(pfn);
@@ -789,6 +790,33 @@ read_page_owner(struct file *file, char
goto out;
}

+ /* Print information relevant to grouping pages by mobility */
+ blocktype = get_pageblock_migratetype(page);
+ pagetype = allocflags_to_migratetype(page->gfp_mask);
+ ret += snprintf(kbuf+ret, count-ret,
+ "PFN %lu Block %lu type %d %s "
+ "Flags %s%s%s%s%s%s%s%s%s%s%s%s\n",
+ pfn,
+ pfn >> pageblock_order,
+ blocktype,
+ blocktype != pagetype ? "Fallback" : " ",
+ PageLocked(page) ? "K" : " ",
+ PageError(page) ? "E" : " ",
+ PageReferenced(page) ? "R" : " ",
+ PageUptodate(page) ? "U" : " ",
+ PageDirty(page) ? "D" : " ",
+ PageLRU(page) ? "L" : " ",
+ PageActive(page) ? "A" : " ",
+ PageSlab(page) ? "S" : " ",
+ PageWriteback(page) ? "W" : " ",
+ PageCompound(page) ? "C" : " ",
+ PageSwapCache(page) ? "B" : " ",
+ PageMappedToDisk(page) ? "M" : " ");
+ if (ret >= count) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
num_written = ret;

for (i = 0; i < 8; i++) {
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.22-rc2-mm1-005_statistics/mm/vmstat.c linux-2.6.22-rc2-mm1-006_statistics_owner/mm/vmstat.c
--- linux-2.6.22-rc2-mm1-005_statistics/mm/vmstat.c 2007-05-24 16:45:22.000000000 +0100
+++ linux-2.6.22-rc2-mm1-006_statistics_owner/mm/vmstat.c 2007-05-24 16:46:57.000000000 +0100
@@ -13,6 +13,7 @@
#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/sched.h>
+#include "internal.h"

#ifdef CONFIG_VM_EVENT_COUNTERS
DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
@@ -552,6 +553,97 @@ static int pagetypeinfo_showblockcount(s
return 0;
}

+#ifdef CONFIG_PAGE_OWNER
+static void pagetypeinfo_showmixedcount_print(struct seq_file *m,
+ pg_data_t *pgdat,
+ struct zone *zone)
+{
+ int mtype, pagetype;
+ unsigned long pfn;
+ unsigned long start_pfn = zone->zone_start_pfn;
+ unsigned long end_pfn = start_pfn + zone->spanned_pages;
+ unsigned long count[MIGRATE_TYPES] = { 0, };
+
+ /* Align PFNs to pageblock_nr_pages boundary */
+ pfn = start_pfn & ~(pageblock_nr_pages-1);
+
+ /*
+ * Walk the zone in pageblock_nr_pages steps. If a page block spans
+ * a zone boundary, it will be double counted between zones. This does
+ * not matter as the mixed block count will still be correct
+ */
+ for (; pfn < end_pfn; pfn += pageblock_nr_pages) {
+ struct page *page;
+ unsigned long offset = 0;
+
+ /* Do not read before the zone start, use a valid page */
+ if (pfn < start_pfn)
+ offset = start_pfn - pfn;
+
+ if (!pfn_valid(pfn + offset))
+ continue;
+
+ page = pfn_to_page(pfn + offset);
+ mtype = get_pageblock_migratetype(page);
+
+ /* Check the block for bad migrate types */
+ for (; offset < pageblock_nr_pages; offset++) {
+ /* Do not past the end of the zone */
+ if (pfn + offset >= end_pfn)
+ break;
+
+ if (!pfn_valid_within(pfn + offset))
+ continue;
+
+ page = pfn_to_page(pfn + offset);
+
+ /* Skip free pages */
+ if (PageBuddy(page)) {
+ offset += (1UL << page_order(page)) - 1UL;
+ continue;
+ }
+ if (page->order < 0)
+ continue;
+
+ pagetype = allocflags_to_migratetype(page->gfp_mask);
+ if (pagetype != mtype) {
+ count[mtype]++;
+ break;
+ }
+
+ /* Move to end of this allocation */
+ offset += (1 << page->order) - 1;
+ }
+ }
+
+ /* Print counts */
+ seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
+ for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
+ seq_printf(m, "%12lu ", count[mtype]);
+ seq_putc(m, '\n');
+}
+#endif /* CONFIG_PAGE_OWNER */
+
+/*
+ * Print out the number of pageblocks for each migratetype that contain pages
+ * of other types. This gives an indication of how well fallbacks are being
+ * contained by rmqueue_fallback(). It requires information from PAGE_OWNER
+ * to determine what is going on
+ */
+static void pagetypeinfo_showmixedcount(struct seq_file *m, pg_data_t *pgdat)
+{
+#ifdef CONFIG_PAGE_OWNER
+ int mtype;
+
+ seq_printf(m, "\n%-23s", "Number of mixed blocks ");
+ for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
+ seq_printf(m, "%12s ", migratetype_names[mtype]);
+ seq_putc(m, '\n');
+
+ walk_zones_in_node(m, pgdat, pagetypeinfo_showmixedcount_print);
+#endif /* CONFIG_PAGE_OWNER */
+}
+
/*
* This prints out statistics in relation to grouping pages by mobility.
* It is expensive to collect so do not constantly read the file.
@@ -565,6 +657,7 @@ static int pagetypeinfo_show(struct seq_
seq_putc(m, '\n');
pagetypeinfo_showfree(m, pgdat);
pagetypeinfo_showblockcount(m, pgdat);
+ pagetypeinfo_showmixedcount(m, pgdat);

return 0;
}
-
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