The patch titled
Subject: thp, vmstats: count deferred split events
has been removed from the -mm tree. Its filename was
thp-vmstats-count-deferred-split-events.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: thp, vmstats: count deferred split events
Count how many times we put a THP in split queue. Currently, it happens
on partial unmap of a THP.
Rapidly growing value can indicate that an application behaves unfriendly
wrt THP: often fault in huge page and then unmap part of it. This leads
to unnecessary memory fragmentation and the application may require
tuning.
The event also can help with debugging kernel [mis-]behaviour.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/vm/transhuge.txt | 5 +++++
include/linux/vm_event_item.h | 1 +
mm/huge_memory.c | 1 +
mm/vmstat.c | 1 +
4 files changed, 8 insertions(+)
diff -puN Documentation/vm/transhuge.txt~thp-vmstats-count-deferred-split-events Documentation/vm/transhuge.txt
--- a/Documentation/vm/transhuge.txt~thp-vmstats-count-deferred-split-events
+++ a/Documentation/vm/transhuge.txt
@@ -229,6 +229,11 @@ thp_split_page is incremented every time
thp_split_page_failed is is incremented if kernel fails to split huge
page. This can happen if the page was pinned by somebody.
+thp_deferred_split_page is incremented when a huge page is put onto split
+ queue. This happens when a huge page is partially unmapped and
+ splitting it would free up some memory. Pages on split queue are
+ going to be split under memory pressure.
+
thp_split_pmd is incremented every time a PMD split into table of PTEs.
This can happen, for instance, when application calls mprotect() or
munmap() on part of huge page. It doesn't split huge page, only
diff -puN include/linux/vm_event_item.h~thp-vmstats-count-deferred-split-events include/linux/vm_event_item.h
--- a/include/linux/vm_event_item.h~thp-vmstats-count-deferred-split-events
+++ a/include/linux/vm_event_item.h
@@ -72,6 +72,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
THP_COLLAPSE_ALLOC_FAILED,
THP_SPLIT_PAGE,
THP_SPLIT_PAGE_FAILED,
+ THP_DEFERRED_SPLIT_PAGE,
THP_SPLIT_PMD,
THP_ZERO_PAGE_ALLOC,
THP_ZERO_PAGE_ALLOC_FAILED,
diff -puN mm/huge_memory.c~thp-vmstats-count-deferred-split-events mm/huge_memory.c
--- a/mm/huge_memory.c~thp-vmstats-count-deferred-split-events
+++ a/mm/huge_memory.c
@@ -3455,6 +3455,7 @@ void deferred_split_huge_page(struct pag
spin_lock_irqsave(&pgdata->split_queue_lock, flags);
if (list_empty(page_deferred_list(page))) {
+ count_vm_event(THP_DEFERRED_SPLIT_PAGE);
list_add_tail(page_deferred_list(page), &pgdata->split_queue);
pgdata->split_queue_len++;
}
diff -puN mm/vmstat.c~thp-vmstats-count-deferred-split-events mm/vmstat.c
--- a/mm/vmstat.c~thp-vmstats-count-deferred-split-events
+++ a/mm/vmstat.c
@@ -848,6 +848,7 @@ const char * const vmstat_text[] = {
"thp_collapse_alloc_failed",
"thp_split_page",
"thp_split_page_failed",
+ "thp_deferred_split_page",
"thp_split_pmd",
"thp_zero_page_alloc",
"thp_zero_page_alloc_failed",
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-2.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-3.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
