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: Davidlohr Bueso <[email protected]> --- include/linux/vm_event_item.h | 4 ++++ include/linux/vmstat.h | 6 ++++++ lib/Kconfig.debug | 10 ++++++++++ mm/vmacache.c | 9 ++++++++- mm/vmstat.c | 4 ++++ 5 files changed, 32 insertions(+), 1 deletion(-) diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h index 486c397..ced9234 100644 --- a/include/linux/vm_event_item.h +++ b/include/linux/vm_event_item.h @@ -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 }; diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h index 45c9cd1..82e7db7 100644 --- a/include/linux/vmstat.h +++ b/include/linux/vmstat.h @@ -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) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 819ac51..9ed3d9b 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -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 diff --git a/mm/vmacache.c b/mm/vmacache.c index d4224b3..e167da2 100644 --- a/mm/vmacache.c +++ b/mm/vmacache.c @@ -78,11 +78,14 @@ 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]; if (vma && vma->vm_start <= addr && vma->vm_end > addr) { BUG_ON(vma->vm_mm != mm); + count_vm_vmacache_event(VMACACHE_FIND_HITS); return vma; } } @@ -100,11 +103,15 @@ 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; diff --git a/mm/vmstat.c b/mm/vmstat.c index 302dd07..82ce17c 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -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 */ -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
