Commit 4f115147 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Linus Torvalds
Browse files

mm,vmacache: add debug data 



Introduce a CONFIG_DEBUG_VM_VMACACHE option to enable counting the cache
hit rate -- exported in /proc/vmstat.

Any updates to the caching scheme needs this kind of data, thus it can
save some work re-implementing the counting all the time.

Signed-off-by: default avatarDavidlohr Bueso <davidlohr@hp.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6f04f48d

include/linux/vm_event_item.h

+4 −0
Original line number Diff line number Diff line
@@ -80,6 +80,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, 
		NR_TLB_LOCAL_FLUSH_ALL,

		NR_TLB_LOCAL_FLUSH_ONE,

#endif /* CONFIG_DEBUG_TLBFLUSH */

#ifdef CONFIG_DEBUG_VM_VMACACHE

		VMACACHE_FIND_CALLS,

		VMACACHE_FIND_HITS,

#endif

		NR_VM_EVENT_ITEMS

};

include/linux/vmstat.h

+6 −0
Original line number Diff line number Diff line
@@ -95,6 +95,12 @@ static inline void vm_events_fold_cpu(int cpu) 
#define count_vm_tlb_events(x, y) do { (void)(y); } while (0)

#endif



#ifdef CONFIG_DEBUG_VM_VMACACHE

#define count_vm_vmacache_event(x) count_vm_event(x)

#else

#define count_vm_vmacache_event(x) do {} while (0)

#endif



#define __count_zone_vm_events(item, zone, delta) \

		__count_vm_events(item##_NORMAL - ZONE_NORMAL + \

		zone_idx(zone), delta)

lib/Kconfig.debug

+10 −0
Original line number Diff line number Diff line
@@ -501,6 +501,16 @@ config DEBUG_VM 


	  If unsure, say N.



config DEBUG_VM_VMACACHE

	bool "Debug VMA caching"

	depends on DEBUG_VM

	help

	  Enable this to turn on VMA caching debug information. Doing so

	  can cause significant overhead, so only enable it in non-production

	  environments.



	  If unsure, say N.



config DEBUG_VM_RB

	bool "Debug VM red-black trees"

	depends on DEBUG_VM

mm/vmacache.c

+10 −2
Original line number Diff line number Diff line
@@ -78,6 +78,8 @@ struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr) 
	if (!vmacache_valid(mm))

		return NULL;



	count_vm_vmacache_event(VMACACHE_FIND_CALLS);



	for (i = 0; i < VMACACHE_SIZE; i++) {

		struct vm_area_struct *vma = current->vmacache[i];
@@ -85,9 +87,11 @@ struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr) 
			continue;

		if (WARN_ON_ONCE(vma->vm_mm != mm))

			break;

		if (vma->vm_start <= addr && vma->vm_end > addr)

		if (vma->vm_start <= addr && vma->vm_end > addr) {

			count_vm_vmacache_event(VMACACHE_FIND_HITS);

			return vma;

		}

	}



	return NULL;

}
@@ -102,12 +106,16 @@ struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm, 
	if (!vmacache_valid(mm))

		return NULL;



	count_vm_vmacache_event(VMACACHE_FIND_CALLS);



	for (i = 0; i < VMACACHE_SIZE; i++) {

		struct vm_area_struct *vma = current->vmacache[i];



		if (vma && vma->vm_start == start && vma->vm_end == end)

		if (vma && vma->vm_start == start && vma->vm_end == end) {

			count_vm_vmacache_event(VMACACHE_FIND_HITS);

			return vma;

		}

	}



	return NULL;

}

mm/vmstat.c

+4 −0
Original line number Diff line number Diff line
@@ -866,6 +866,10 @@ const char * const vmstat_text[] = { 
	"nr_tlb_local_flush_one",

#endif /* CONFIG_DEBUG_TLBFLUSH */



#ifdef CONFIG_DEBUG_VM_VMACACHE

	"vmacache_find_calls",

	"vmacache_find_hits",

#endif

#endif /* CONFIG_VM_EVENTS_COUNTERS */

};

#endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */

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