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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2013-11-13 03:07:50 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2013-11-13 07:09:07 +0400
commit46c77e2bb07eba3b38edfec76873f12942c49dd3 (patch)
tree2e6dd491627079f3e377e948f23137dd0c4cab40 /include/linux/kernel-page-flags.h
parentec8e41aec13005fed0dbee002fb8c99b4e001d50 (diff)
downloadlinux-46c77e2bb07eba3b38edfec76873f12942c49dd3.tar.xz
tools/vm/page-types.c: support KPF_SOFTDIRTY bit
Soft dirty bit allows us to track which pages are written since the last clear_ref (by "echo 4 > /proc/pid/clear_refs".) This is useful for userspace applications to know their memory footprints. Note that the kernel exposes this flag via bit[55] of /proc/pid/pagemap, and the semantics is not a default one (scheduled to be the default in the near future.) However, it shifts to the new semantics at the first clear_ref, and the users of soft dirty bit always do it before utilizing the bit, so that's not a big deal. Users must avoid relying on the bit in page-types before the first clear_ref. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/kernel-page-flags.h')
-rw-r--r--include/linux/kernel-page-flags.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/kernel-page-flags.h b/include/linux/kernel-page-flags.h
index 546eb6a76934..f65ce09784f1 100644
--- a/include/linux/kernel-page-flags.h
+++ b/include/linux/kernel-page-flags.h
@@ -15,5 +15,6 @@
#define KPF_OWNER_PRIVATE 37
#define KPF_ARCH 38
#define KPF_UNCACHED 39
+#define KPF_SOFTDIRTY 40
#endif /* LINUX_KERNEL_PAGE_FLAGS_H */