linux-stable/include/linux/vm_event_item.h
Saravanan D 575299ea18 x86/mm: track linear mapping split events
To help with debugging the sluggishness caused by TLB miss/reload, we
introduce monotonic hugepage [direct mapped] split event counts since
system state: SYSTEM_RUNNING to be displayed as part of /proc/vmstat in
x86 servers

The lifetime split event information will be displayed at the bottom of
/proc/vmstat
  ....
  swap_ra 0
  swap_ra_hit 0
  direct_map_level2_splits 94
  direct_map_level3_splits 4
  nr_unstable 0
  ....

One of the many lasting sources of direct hugepage splits is kernel
tracing (kprobes, tracepoints).

Note that the kernel's code segment [512 MB] points to the same physical
addresses that have been already mapped in the kernel's direct mapping
range.

Source : Documentation/x86/x86_64/mm.rst

When we enable kernel tracing, the kernel has to modify
attributes/permissions of the text segment hugepages that are direct
mapped causing them to split.

Kernel's direct mapped hugepages do not coalesce back after split and
remain in place for the remainder of the lifetime.

An instance of direct page splits when we turn on dynamic kernel tracing
....
cat /proc/vmstat | grep -i direct_map_level
direct_map_level2_splits 784
direct_map_level3_splits 12
bpftrace -e 'tracepoint:raw_syscalls:sys_enter { @ [pid, comm] =
count(); }'
cat /proc/vmstat | grep -i
direct_map_level
direct_map_level2_splits 789
direct_map_level3_splits 12
....

Link: https://lkml.kernel.org/r/20210218235744.1040634-1-saravanand@fb.com
Signed-off-by: Saravanan D <saravanand@fb.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 11:27:25 -07:00

142 lines
3.4 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef VM_EVENT_ITEM_H_INCLUDED
#define VM_EVENT_ITEM_H_INCLUDED
#ifdef CONFIG_ZONE_DMA
#define DMA_ZONE(xx) xx##_DMA,
#else
#define DMA_ZONE(xx)
#endif
#ifdef CONFIG_ZONE_DMA32
#define DMA32_ZONE(xx) xx##_DMA32,
#else
#define DMA32_ZONE(xx)
#endif
#ifdef CONFIG_HIGHMEM
#define HIGHMEM_ZONE(xx) xx##_HIGH,
#else
#define HIGHMEM_ZONE(xx)
#endif
#define FOR_ALL_ZONES(xx) DMA_ZONE(xx) DMA32_ZONE(xx) xx##_NORMAL, HIGHMEM_ZONE(xx) xx##_MOVABLE
enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
FOR_ALL_ZONES(PGALLOC),
FOR_ALL_ZONES(ALLOCSTALL),
FOR_ALL_ZONES(PGSCAN_SKIP),
PGFREE, PGACTIVATE, PGDEACTIVATE, PGLAZYFREE,
PGFAULT, PGMAJFAULT,
PGLAZYFREED,
PGREFILL,
PGREUSE,
PGSTEAL_KSWAPD,
PGSTEAL_DIRECT,
PGSCAN_KSWAPD,
PGSCAN_DIRECT,
PGSCAN_DIRECT_THROTTLE,
PGSCAN_ANON,
PGSCAN_FILE,
PGSTEAL_ANON,
PGSTEAL_FILE,
#ifdef CONFIG_NUMA
PGSCAN_ZONE_RECLAIM_FAILED,
#endif
PGINODESTEAL, SLABS_SCANNED, KSWAPD_INODESTEAL,
KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,
PAGEOUTRUN, PGROTATED,
DROP_PAGECACHE, DROP_SLAB,
OOM_KILL,
#ifdef CONFIG_NUMA_BALANCING
NUMA_PTE_UPDATES,
NUMA_HUGE_PTE_UPDATES,
NUMA_HINT_FAULTS,
NUMA_HINT_FAULTS_LOCAL,
NUMA_PAGE_MIGRATE,
#endif
#ifdef CONFIG_MIGRATION
PGMIGRATE_SUCCESS, PGMIGRATE_FAIL,
THP_MIGRATION_SUCCESS,
THP_MIGRATION_FAIL,
THP_MIGRATION_SPLIT,
#endif
#ifdef CONFIG_COMPACTION
COMPACTMIGRATE_SCANNED, COMPACTFREE_SCANNED,
COMPACTISOLATED,
COMPACTSTALL, COMPACTFAIL, COMPACTSUCCESS,
KCOMPACTD_WAKE,
KCOMPACTD_MIGRATE_SCANNED, KCOMPACTD_FREE_SCANNED,
#endif
#ifdef CONFIG_HUGETLB_PAGE
HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
#endif
#ifdef CONFIG_CMA
CMA_ALLOC_SUCCESS,
CMA_ALLOC_FAIL,
#endif
UNEVICTABLE_PGCULLED, /* culled to noreclaim list */
UNEVICTABLE_PGSCANNED, /* scanned for reclaimability */
UNEVICTABLE_PGRESCUED, /* rescued from noreclaim list */
UNEVICTABLE_PGMLOCKED,
UNEVICTABLE_PGMUNLOCKED,
UNEVICTABLE_PGCLEARED, /* on COW, page truncate */
UNEVICTABLE_PGSTRANDED, /* unable to isolate on unlock */
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
THP_FAULT_ALLOC,
THP_FAULT_FALLBACK,
THP_FAULT_FALLBACK_CHARGE,
THP_COLLAPSE_ALLOC,
THP_COLLAPSE_ALLOC_FAILED,
THP_FILE_ALLOC,
THP_FILE_FALLBACK,
THP_FILE_FALLBACK_CHARGE,
THP_FILE_MAPPED,
THP_SPLIT_PAGE,
THP_SPLIT_PAGE_FAILED,
THP_DEFERRED_SPLIT_PAGE,
THP_SPLIT_PMD,
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
THP_SPLIT_PUD,
#endif
THP_ZERO_PAGE_ALLOC,
THP_ZERO_PAGE_ALLOC_FAILED,
THP_SWPOUT,
THP_SWPOUT_FALLBACK,
#endif
#ifdef CONFIG_MEMORY_BALLOON
BALLOON_INFLATE,
BALLOON_DEFLATE,
#ifdef CONFIG_BALLOON_COMPACTION
BALLOON_MIGRATE,
#endif
#endif
#ifdef CONFIG_DEBUG_TLBFLUSH
NR_TLB_REMOTE_FLUSH, /* cpu tried to flush others' tlbs */
NR_TLB_REMOTE_FLUSH_RECEIVED,/* cpu received ipi for flush */
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
#ifdef CONFIG_SWAP
SWAP_RA,
SWAP_RA_HIT,
#endif
#ifdef CONFIG_X86
DIRECT_MAP_LEVEL2_SPLIT,
DIRECT_MAP_LEVEL3_SPLIT,
#endif
NR_VM_EVENT_ITEMS
};
#ifndef CONFIG_TRANSPARENT_HUGEPAGE
#define THP_FILE_ALLOC ({ BUILD_BUG(); 0; })
#define THP_FILE_FALLBACK ({ BUILD_BUG(); 0; })
#define THP_FILE_FALLBACK_CHARGE ({ BUILD_BUG(); 0; })
#define THP_FILE_MAPPED ({ BUILD_BUG(); 0; })
#endif
#endif /* VM_EVENT_ITEM_H_INCLUDED */