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Commit 46c77e2b authored by Naoya Horiguchi's avatar Naoya Horiguchi Committed by Linus Torvalds
Browse files

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: default avatarNaoya 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ec8e41ae

include/linux/kernel-page-flags.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

tools/vm/page-types.c

+20 −12
Original line number Diff line number Diff line
@@ -59,12 +59,14 @@ 
#define PM_PSHIFT_BITS      6

#define PM_PSHIFT_OFFSET    (PM_STATUS_OFFSET - PM_PSHIFT_BITS)

#define PM_PSHIFT_MASK      (((1LL << PM_PSHIFT_BITS) - 1) << PM_PSHIFT_OFFSET)

#define PM_PSHIFT(x)        (((u64) (x) << PM_PSHIFT_OFFSET) & PM_PSHIFT_MASK)

#define __PM_PSHIFT(x)      (((uint64_t) (x) << PM_PSHIFT_OFFSET) & PM_PSHIFT_MASK)

#define PM_PFRAME_MASK      ((1LL << PM_PSHIFT_OFFSET) - 1)

#define PM_PFRAME(x)        ((x) & PM_PFRAME_MASK)



#define __PM_SOFT_DIRTY      (1LL)

#define PM_PRESENT          PM_STATUS(4LL)

#define PM_SWAP             PM_STATUS(2LL)

#define PM_SOFT_DIRTY       __PM_PSHIFT(__PM_SOFT_DIRTY)





/*
@@ -83,6 +85,7 @@ 
#define KPF_OWNER_PRIVATE	37

#define KPF_ARCH		38

#define KPF_UNCACHED		39

#define KPF_SOFTDIRTY		40



/* [48-] take some arbitrary free slots for expanding overloaded flags

 * not part of kernel API
@@ -132,6 +135,7 @@ static const char * const page_flag_names[] = { 
	[KPF_OWNER_PRIVATE]	= "O:owner_private",

	[KPF_ARCH]		= "h:arch",

	[KPF_UNCACHED]		= "c:uncached",

	[KPF_SOFTDIRTY]		= "f:softdirty",



	[KPF_READAHEAD]		= "I:readahead",

	[KPF_SLOB_FREE]		= "P:slob_free",
@@ -417,7 +421,7 @@ static int bit_mask_ok(uint64_t flags) 
	return 1;

}



static uint64_t expand_overloaded_flags(uint64_t flags)

static uint64_t expand_overloaded_flags(uint64_t flags, uint64_t pme)

{

	/* SLOB/SLUB overload several page flags */

	if (flags & BIT(SLAB)) {
@@ -433,6 +437,9 @@ static uint64_t expand_overloaded_flags(uint64_t flags) 
	if ((flags & (BIT(RECLAIM) | BIT(WRITEBACK))) == BIT(RECLAIM))

		flags ^= BIT(RECLAIM) | BIT(READAHEAD);



	if (pme & PM_SOFT_DIRTY)

		flags |= BIT(SOFTDIRTY);



	return flags;

}
@@ -448,11 +455,11 @@ static uint64_t well_known_flags(uint64_t flags) 
	return flags;

}



static uint64_t kpageflags_flags(uint64_t flags)

static uint64_t kpageflags_flags(uint64_t flags, uint64_t pme)

{

	flags = expand_overloaded_flags(flags);



	if (!opt_raw)

	if (opt_raw)

		flags = expand_overloaded_flags(flags, pme);

	else

		flags = well_known_flags(flags);



	return flags;
@@ -545,9 +552,9 @@ static size_t hash_slot(uint64_t flags) 
}



static void add_page(unsigned long voffset,

		     unsigned long offset, uint64_t flags)

		     unsigned long offset, uint64_t flags, uint64_t pme)

{

	flags = kpageflags_flags(flags);

	flags = kpageflags_flags(flags, pme);



	if (!bit_mask_ok(flags))

		return;
@@ -569,7 +576,8 @@ static void add_page(unsigned long voffset, 
#define KPAGEFLAGS_BATCH	(64 << 10)	/* 64k pages */

static void walk_pfn(unsigned long voffset,

		     unsigned long index,

		     unsigned long count)

		     unsigned long count,

		     uint64_t pme)

{

	uint64_t buf[KPAGEFLAGS_BATCH];

	unsigned long batch;
@@ -583,7 +591,7 @@ static void walk_pfn(unsigned long voffset, 
			break;



		for (i = 0; i < pages; i++)

			add_page(voffset + i, index + i, buf[i]);

			add_page(voffset + i, index + i, buf[i], pme);



		index += pages;

		count -= pages;
@@ -608,7 +616,7 @@ static void walk_vma(unsigned long index, unsigned long count) 
		for (i = 0; i < pages; i++) {

			pfn = pagemap_pfn(buf[i]);

			if (pfn)

				walk_pfn(index + i, pfn, 1);

				walk_pfn(index + i, pfn, 1, buf[i]);

		}



		index += pages;
@@ -659,7 +667,7 @@ static void walk_addr_ranges(void) 


	for (i = 0; i < nr_addr_ranges; i++)

		if (!opt_pid)

			walk_pfn(0, opt_offset[i], opt_size[i]);

			walk_pfn(0, opt_offset[i], opt_size[i], 0);

		else

			walk_task(opt_offset[i], opt_size[i]);