linux/mm
Nicholas Piggin 6290602709 mm: add PageWaiters indicating tasks are waiting for a page bit
Add a new page flag, PageWaiters, to indicate the page waitqueue has
tasks waiting. This can be tested rather than testing waitqueue_active
which requires another cacheline load.

This bit is always set when the page has tasks on page_waitqueue(page),
and is set and cleared under the waitqueue lock. It may be set when
there are no tasks on the waitqueue, which will cause a harmless extra
wakeup check that will clears the bit.

The generic bit-waitqueue infrastructure is no longer used for pages.
Instead, waitqueues are used directly with a custom key type. The
generic code was not flexible enough to have PageWaiters manipulation
under the waitqueue lock (which simplifies concurrency).

This improves the performance of page lock intensive microbenchmarks by
2-3%.

Putting two bits in the same word opens the opportunity to remove the
memory barrier between clearing the lock bit and testing the waiters
bit, after some work on the arch primitives (e.g., ensuring memory
operand widths match and cover both bits).

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Andrew Lutomirski <luto@kernel.org>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-25 11:54:48 -08:00
..
kasan Power management material for v4.10-rc1 2016-12-13 10:41:53 -08:00
backing-dev.c writeback: track if we're sleeping on progress in balance_dirty_pages() 2016-11-08 08:28:55 -07:00
balloon_compaction.c
bootmem.c mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping 2016-10-11 15:06:33 -07:00
cleancache.c
cma_debug.c
cma.c mm/cma.c: check the max limit for cma allocation 2016-11-11 08:12:37 -08:00
cma.h
compaction.c mm, compaction: allow compaction for GFP_NOFS requests 2016-12-14 16:04:07 -08:00
debug_page_ref.c
debug.c mm, debug: print raw struct page data in __dump_page() 2016-12-12 18:55:08 -08:00
dmapool.c
early_ioremap.c
fadvise.c mm: fadvise: avoid expensive remote LRU cache draining after FADV_DONTNEED 2016-12-20 09:48:46 -08:00
failslab.c
filemap.c mm: add PageWaiters indicating tasks are waiting for a page bit 2016-12-25 11:54:48 -08:00
frame_vector.c mm: replace get_vaddr_frames() write/force parameters with gup_flags 2016-10-19 08:11:24 -07:00
frontswap.c
gup.c mm: unexport __get_user_pages_unlocked() 2016-12-14 16:04:09 -08:00
highmem.c
huge_memory.c mm: join struct fault_env and vm_fault 2016-12-14 16:04:09 -08:00
hugetlb_cgroup.c
hugetlb.c mm: add tlb_remove_check_page_size_change to track page size change 2016-12-12 18:55:07 -08:00
hwpoison-inject.c
init-mm.c mm: Add a user_ns owner to mm_struct and fix ptrace permission checks 2016-11-22 11:49:48 -06:00
internal.h mm: add PageWaiters indicating tasks are waiting for a page bit 2016-12-25 11:54:48 -08:00
interval_tree.c
Kconfig mm: THP page cache support for ppc64 2016-12-12 18:55:08 -08:00
Kconfig.debug
khugepaged.c radix-tree: improve multiorder iterators 2016-12-14 16:04:10 -08:00
kmemcheck.c
kmemleak-test.c
kmemleak.c kmemleak: fix reference to Documentation 2016-12-12 18:55:07 -08:00
ksm.c mm,ksm: add __GFP_HIGH to the allocation in alloc_stable_node() 2016-10-07 18:46:29 -07:00
list_lru.c mm/list_lru.c: avoid error-path NULL pointer deref 2016-10-27 18:43:42 -07:00
maccess.c
madvise.c mm: add tlb_remove_check_page_size_change to track page size change 2016-12-12 18:55:07 -08:00
Makefile Disable the __builtin_return_address() warning globally after all 2016-10-12 10:23:41 -07:00
memblock.c mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping 2016-10-11 15:06:33 -07:00
memcontrol.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
memory_hotplug.c mm: remove x86-only restriction of movable_node 2016-12-12 18:55:07 -08:00
memory-failure.c mm: Use owner_priv bit for PageSwapCache, valid when PageSwapBacked 2016-12-25 11:54:48 -08:00
memory.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mempolicy.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mempool.c
memtest.c
migrate.c mm: Use owner_priv bit for PageSwapCache, valid when PageSwapBacked 2016-12-25 11:54:48 -08:00
mincore.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mlock.c thp: fix corner case of munlock() of PTE-mapped THPs 2016-11-30 16:32:52 -08:00
mm_init.c
mmap.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mmu_context.c
mmu_notifier.c
mmzone.c
mprotect.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mremap.c mremap: move_ptes: check pte dirty after its removal 2016-11-29 08:20:24 -08:00
msync.c
nobootmem.c mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping 2016-10-11 15:06:33 -07:00
nommu.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
oom_kill.c oom: print nodemask in the oom report 2016-10-07 18:46:29 -07:00
page_alloc.c mm: add support for releasing multiple instances of a page 2016-12-14 16:04:08 -08:00
page_counter.c
page_ext.c mm/page_ext: support extra space allocation by page_ext user 2016-10-07 18:46:27 -07:00
page_idle.c
page_io.c writeback: add wbc_to_write_flags() 2016-11-02 10:24:03 -06:00
page_isolation.c mm/page_isolation: fix typo: "paes" -> "pages" 2016-10-07 18:46:29 -07:00
page_owner.c mm/page_owner: don't define fields on struct page_ext by hard-coding 2016-10-07 18:46:27 -07:00
page_poison.c
page-writeback.c radix-tree: delete radix_tree_range_tag_if_tagged() 2016-12-14 16:04:10 -08:00
pagewalk.c
percpu-km.c
percpu-vm.c
percpu.c Merge branch 'for-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2016-12-13 12:34:47 -08:00
pgtable-generic.c
process_vm_access.c mm: unexport __get_user_pages_unlocked() 2016-12-14 16:04:09 -08:00
quicklist.c
readahead.c mm: don't cap request size based on read-ahead setting 2016-12-12 18:55:08 -08:00
rmap.c mm, rmap: handle anon_vma_prepare() common case inline 2016-12-12 18:55:08 -08:00
shmem.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
slab_common.c mm/slab_common.c: check kmem_create_cache flags are common 2016-12-12 18:55:06 -08:00
slab.c Merge branch 'for-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2016-12-13 12:59:57 -08:00
slab.h mm, slab: maintain total slab count instead of active count 2016-12-12 18:55:07 -08:00
slob.c slub: move synchronize_sched out of slab_mutex on shrink 2016-12-12 18:55:06 -08:00
slub.c slub: avoid false-postive warning 2016-12-12 18:55:06 -08:00
sparse-vmemmap.c
sparse.c
swap_cgroup.c
swap_state.c mm, swap: use offset of swap entry as key of swap cache 2016-10-07 18:46:28 -07:00
swap.c mm: add PageWaiters indicating tasks are waiting for a page bit 2016-12-25 11:54:48 -08:00
swapfile.c mm: add three more cond_resched() in swapoff 2016-12-12 18:55:08 -08:00
truncate.c mm: workingset: move shadow entry tracking to radix tree exceptional tracking 2016-12-12 18:55:08 -08:00
usercopy.c
userfaultfd.c
util.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
vmacache.c mm: unrig VMA cache hit ratio 2016-10-07 18:46:27 -07:00
vmalloc.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
vmpressure.c
vmscan.c Merge branch 'akpm' (patches from Andrew) 2016-12-12 20:50:02 -08:00
vmstat.c mm/vmstat: Convert to hotplug state machine 2016-12-02 00:52:35 +01:00
workingset.c mm: workingset: update shadow limit to reflect bigger active list 2016-12-12 18:55:08 -08:00
z3fold.c
zbud.c
zpool.c
zsmalloc.c mm/zsmalloc: Convert to hotplug state machine 2016-12-02 00:52:36 +01:00
zswap.c mm/zswap: Convert pool to hotplug state machine 2016-12-02 00:52:36 +01:00