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f7a5f132b447cb6301ab3f0b0468a63db29e41f5
android_kernel_xiaomi_sm8450/fs
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Alexey Dobriyan f7a5f132b4 proc: faster /proc/*/status 
top(1) opens the following files for every PID:

	/proc/*/stat
	/proc/*/statm
	/proc/*/status

This patch switches /proc/*/status away from seq_printf().
The result is 13.5% speedup.

Benchmark is open("/proc/self/status")+read+close 1.000.000 million times.

				BEFORE
$ perf stat -r 10 taskset -c 3 ./proc-self-status

 Performance counter stats for 'taskset -c 3 ./proc-self-status' (10 runs):

      10748.474301      task-clock (msec)         #    0.954 CPUs utilized            ( +-  0.91% )
                12      context-switches          #    0.001 K/sec                    ( +-  1.09% )
                 1      cpu-migrations            #    0.000 K/sec
               104      page-faults               #    0.010 K/sec                    ( +-  0.45% )
    37,424,127,876      cycles                    #    3.482 GHz                      ( +-  0.04% )
     8,453,010,029      stalled-cycles-frontend   #   22.59% frontend cycles idle     ( +-  0.12% )
     3,747,609,427      stalled-cycles-backend    #  10.01% backend cycles idle       ( +-  0.68% )
    65,632,764,147      instructions              #    1.75  insn per cycle
                                                  #    0.13  stalled cycles per insn  ( +-  0.00% )
    13,981,324,775      branches                  # 1300.773 M/sec                    ( +-  0.00% )
       138,967,110      branch-misses             #    0.99% of all branches          ( +-  0.18% )

      11.263885428 seconds time elapsed                                          ( +-  0.04% )
      ^^^^^^^^^^^^

				AFTER
$ perf stat -r 10 taskset -c 3 ./proc-self-status

 Performance counter stats for 'taskset -c 3 ./proc-self-status' (10 runs):

       9010.521776      task-clock (msec)         #    0.925 CPUs utilized            ( +-  1.54% )
                11      context-switches          #    0.001 K/sec                    ( +-  1.54% )
                 1      cpu-migrations            #    0.000 K/sec                    ( +- 11.11% )
               103      page-faults               #    0.011 K/sec                    ( +-  0.60% )
    32,352,310,603      cycles                    #    3.591 GHz                      ( +-  0.07% )
     7,849,199,578      stalled-cycles-frontend   #   24.26% frontend cycles idle     ( +-  0.27% )
     3,269,738,842      stalled-cycles-backend    #  10.11% backend cycles idle       ( +-  0.73% )
    56,012,163,567      instructions              #    1.73  insn per cycle
                                                  #    0.14  stalled cycles per insn  ( +-  0.00% )
    11,735,778,795      branches                  # 1302.453 M/sec                    ( +-  0.00% )
        98,084,459      branch-misses             #    0.84% of all branches          ( +-  0.28% )

       9.741247736 seconds time elapsed                                          ( +-  0.07% )
       ^^^^^^^^^^^

Link: http://lkml.kernel.org/r/20160806125608.GB1187@p183.telecom.by
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-07 18:46:30 -07:00
..
9p
Merge branch 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2016-08-07 10:01:14 -04:00
adfs
Merge branch 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2016-08-07 10:01:14 -04:00
affs
get rid of 'parent' argument of ->d_compare()
2016-07-31 16:37:25 -04:00
afs
rxrpc: Rewrite the data and ack handling code
2016-09-08 11:10:12 +01:00
autofs4
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2016-10-06 09:52:23 -07:00
befs
fs/befs/io.c:befs_bread(): remove unneeded initialization to NULL
2016-05-23 17:04:14 -07:00
bfs
more trivial ->iterate_shared conversions
2016-05-09 11:41:14 -04:00
btrfs
Merge branch 'for-linus-4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs
2016-09-23 13:39:37 -07:00
cachefiles
cachefiles: Fix race between inactivating and culling a cache object
2016-08-03 13:33:26 -04:00
ceph
ceph: do not modify fi->frag in need_reset_readdir()
2016-09-05 14:30:35 +02:00
cifs
Move check for prefix path to within cifs_get_root()
2016-09-09 23:58:07 -05:00
coda
drop redundant ->owner initializations
2016-05-29 19:08:00 -04:00
configfs
configfs: Return -EFBIG from configfs_write_bin_file.
2016-09-16 12:58:28 +02:00
cramfs
more trivial ->iterate_shared conversions
2016-05-09 11:41:14 -04:00
crypto
fscrypto: require write access to mount to set encryption policy
2016-09-10 01:18:57 -04:00
debugfs
debugfs: propagate release() call result
2016-09-27 12:45:57 +02:00
devpts
devpts: Change the owner of /dev/pts/ptmx to the mounter of /dev/pts
2016-09-23 11:31:31 +02:00
dlm
dlm: fix malfunction of dlm_tool caused by debugfs changes
2016-08-26 13:22:14 -05:00
ecryptfs
ecryptfs: don't allow mmap when the lower fs doesn't support it
2016-07-08 10:35:28 -05:00
efivarfs
fs/efivarfs: Fix double kfree() in error path
2016-09-09 16:08:48 +01:00
efs
fs/efs/super.c: fix return value
2016-05-20 17:58:30 -07:00
exofs
block, fs, mm, drivers: use bio set/get op accessors
2016-06-07 13:41:38 -06:00
exportfs
introduce a parallel variant of ->iterate()
2016-05-02 19:49:29 -04:00
ext2
ext2/4, xfs: call thp_get_unmapped_area() for pmd mappings
2016-10-07 18:46:28 -07:00
ext4
ext2/4, xfs: call thp_get_unmapped_area() for pmd mappings
2016-10-07 18:46:28 -07:00
f2fs
Merge tag 'for-f2fs-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
2016-10-06 15:30:40 -07:00
fat
Merge branch 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2016-08-07 10:01:14 -04:00
freevxfs
freevxfs: update Kconfig information
2016-06-13 10:20:39 +02:00
fscache
Merge branch 'd_real' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs into work.misc
2016-06-30 23:34:49 -04:00
fuse
fuse: limit xattr returned size
2016-10-03 11:06:05 +02:00
gfs2
Merge tag 'gfs2-4.8.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2
2016-10-04 13:42:13 -07:00
hfs
Merge branch 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2016-08-07 10:01:14 -04:00
hfsplus
Merge branch 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2016-08-07 10:01:14 -04:00
hostfs
hostfs: Freeing an ERR_PTR in hostfs_fill_sb_common()
2016-08-04 00:18:10 +02:00
hpfs
get rid of 'parent' argument of ->d_compare()
2016-07-31 16:37:25 -04:00
hugetlbfs
mm: remove unnecessary condition in remove_inode_hugepages
2016-10-07 18:46:29 -07:00
isofs
get rid of 'parent' argument of ->d_compare()
2016-07-31 16:37:25 -04:00
jbd2
Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
2016-07-26 18:35:55 -07:00
jffs2
vfs: make the string hashes salt the hash
2016-06-10 20:21:46 -07:00
jfs
jfs: Simplify code
2016-09-06 12:17:24 -05:00
kernfs
kernfs: don't depend on d_find_any_alias() when generating notifications
2016-08-31 14:48:52 +02:00
lockd
Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2016-07-28 12:59:05 -07:00
logfs
Merge branch 'work.const-qstr' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2016-08-06 09:49:02 -04:00
minix
simple local filesystems: switch to ->iterate_shared()
2016-05-02 19:49:32 -04:00
ncpfs
get rid of 'parent' argument of ->d_compare()
2016-07-31 16:37:25 -04:00
nfs
mm: remove page_file_index
2016-10-07 18:46:28 -07:00
nfs_common
lockd: NLM grace period shouldn't block NFSv4 opens
2015-08-13 10:22:06 -04:00
nfsd
nfsd: don't return an unhashed lock stateid after taking mutex
2016-08-12 16:10:25 -04:00
nilfs2
nilfs2: move ioctl interface and disk layout to uapi separately
2016-08-02 19:35:21 -04:00
nls
…
notify
fsnotify: clean up spinlock assertions
2016-10-07 18:46:26 -07:00
ntfs
Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2016-07-28 12:59:05 -07:00
ocfs2
ocfs2: fix undefined struct variable in inode.h
2016-10-07 18:46:26 -07:00
omfs
more trivial ->iterate_shared conversions
2016-05-09 11:41:14 -04:00
openpromfs
more trivial ->iterate_shared conversions
2016-05-09 11:41:14 -04:00
orangefs
Revert "orangefs: bump minimum userspace version"
2016-10-03 15:07:36 -04:00
overlayfs
Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
2016-10-04 14:48:27 -07:00
proc
proc: faster /proc/*/status
2016-10-07 18:46:30 -07:00
pstore
ramoops: move spin_lock_init after kmalloc error checking
2016-09-08 15:01:13 -07:00
qnx4
more trivial ->iterate_shared conversions
2016-05-09 11:41:14 -04:00
qnx6
more trivial ->iterate_shared conversions
2016-05-09 11:41:14 -04:00
quota
quota: fill in Q_XGETQSTAT inode information for inactive quotas
2016-08-15 17:43:31 +02:00
ramfs
ipc/shm: fix crash if CONFIG_SHMEM is not set
2016-09-19 15:36:17 -07:00
reiserfs
reiserfs: Unlock superblock before calling reiserfs_quota_on_mount()
2016-09-16 17:20:59 +02:00
romfs
romfs, squashfs: switch to ->iterate_shared()
2016-05-09 11:41:15 -04:00
squashfs
fs: have ll_rw_block users pass in op and flags separately
2016-06-07 13:41:38 -06:00
sysfs
sysfs print name of undiscoverable attribute group
2016-09-27 12:24:29 +02:00
sysv
vfs: make the string hashes salt the hash
2016-06-10 20:21:46 -07:00
tracefs
tracefs: ->d_parent is never NULL or negative...
2016-05-29 16:22:07 -04:00
ubifs
ubifs: Fix xattr generic handler usage
2016-08-23 23:02:52 +02:00
udf
udf: don't bother with full-page write optimisations in adinicb case
2016-09-19 10:47:01 +02:00
ufs
Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2016-07-28 12:59:05 -07:00
xfs
ext2/4, xfs: call thp_get_unmapped_area() for pmd mappings
2016-10-07 18:46:28 -07:00
aio.c
aio: mark AIO pseudo-fs noexec
2016-09-15 15:49:28 -07:00
anon_inodes.c
…
attr.c
vfs: Don't modify inodes with a uid or gid unknown to the vfs
2016-07-05 15:06:46 -05:00
bad_inode.c
switch ->setxattr() to passing dentry and inode separately
2016-05-27 20:09:16 -04:00
binfmt_aout.c
fs: fix binfmt_aout.c build error
2016-05-28 16:34:59 -07:00
binfmt_elf_fdpic.c
elf_fdpic_transfer_args_to_stack(): make it generic
2016-07-25 16:51:49 +10:00
binfmt_elf.c
x86/coredump: Use pr_reg size, rather that TIF_IA32 flag
2016-09-14 21:28:10 +02:00
binfmt_em86.c
fs/binfmt_em86.c: fix incompatible pointer type
2016-08-02 19:35:15 -04:00
binfmt_flat.c
binfmt_flat: allow compressed flat binary format to work on MMU systems
2016-07-28 13:29:12 +10:00
binfmt_misc.c
Merge tag 'binfmt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/binfmt_misc
2016-08-07 10:13:14 -04:00
binfmt_script.c
…
block_dev.c
fs/block_dev: fix potential NULL ptr deref in freeze_bdev()
2016-08-25 08:38:26 -06:00
buffer.c
Merge tag 'xfs-for-linus-4.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs
2016-07-27 09:53:35 -07:00
char_dev.c
chardev: add missing line break in pr_warn
2016-07-14 16:21:53 +09:00
compat_binfmt_elf.c
…
compat_ioctl.c
[media] cec: add compat32 ioctl support
2016-06-28 10:00:13 -03:00
compat.c
Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
2016-05-24 12:55:26 -07:00
coredump.c
coredump: fix dumping through pipes
2016-06-07 22:07:09 -04:00
dax.c
thp: reduce usage of huge zero page's atomic counter
2016-10-07 18:46:28 -07:00
dcache.c
Merge branch 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2016-08-07 10:01:14 -04:00
dcookies.c
…
direct-io.c
direct-io: use bio set/get op accessors
2016-06-07 13:41:38 -06:00
drop_caches.c
inode: convert inode_sb_list_lock to per-sb
2015-08-17 18:39:46 -04:00
eventfd.c
eventfd: document lockless access in eventfd_poll
2016-03-22 15:36:02 -07:00
eventpoll.c
fs: poll/select/recvmmsg: use timespec64 for timeout events
2016-05-19 19:12:14 -07:00
exec.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu
2016-08-04 18:04:44 -04:00
fcntl.c
fcntl: allow to set O_DIRECT flag on pipe
2016-01-09 02:55:37 -05:00
fhandle.c
fs/coredump: prevent fsuid=0 dumps into user-controlled directories
2016-03-22 15:36:02 -07:00
file_table.c
fs, file table: reinit files_stat.max_files after deferred memory initialisation
2015-08-07 04:39:40 +03:00
file.c
give readdir(2)/getdents(2)/etc. uniform exclusion with lseek()
2016-05-02 19:49:28 -04:00
filesystems.c
find_filesystem(): simplify comparison
2016-01-19 12:02:23 -05:00
fs_pin.c
…
fs_struct.c
…
fs-writeback.c
mm, writeback: flush plugged IO in wakeup_flusher_threads()
2016-08-09 19:58:06 -06:00
inode.c
Merge branch 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2016-08-07 10:01:14 -04:00
internal.h
iomap: expose iomap_apply outside iomap.c
2016-09-19 11:24:49 +10:00
ioctl.c
vfs: cap dedupe request structure size at PAGE_SIZE
2016-09-15 13:29:52 -07:00
iomap.c
Merge branch 'iomap-4.9-dax' into for-next
2016-10-03 09:53:59 +11:00
Kconfig
mm/hugetlb: introduce ARCH_HAS_GIGANTIC_PAGE
2016-10-07 18:46:29 -07:00
Kconfig.binfmt
ARM: 8594/1: enable binfmt_flat on systems with an MMU
2016-08-12 16:47:05 +01:00
libfs.c
lockless next_positive()
2016-06-20 17:11:29 -04:00
locks.c
Merge tag 'locks-v4.9-1' of git://git.samba.org/jlayton/linux
2016-10-04 13:36:19 -07:00
Makefile
fs: introduce iomap infrastructure
2016-06-21 09:23:11 +10:00
mbcache.c
mbcache: add reusable flag to cache entries
2016-02-22 22:44:04 -05:00
mount.h
mnt: Add a per mount namespace limit on the number of mounts
2016-09-30 12:46:48 -05:00
mpage.c
block/mm: make bdev_ops->rw_page() take a bool for read/write
2016-08-07 14:41:02 -06:00
namei.c
fs: return EPERM on immutable inode
2016-08-07 10:03:31 -04:00
namespace.c
mnt: Add a per mount namespace limit on the number of mounts
2016-09-30 12:46:48 -05:00
no-block.c
…
nsfs.c
nsfs: Simplify __ns_get_path
2016-09-22 20:06:20 -05:00
open.c
Merge tag 'binfmt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/binfmt_misc
2016-08-07 10:13:14 -04:00
pipe.c
mm: memcontrol: only mark charged pages with PageKmemcg
2016-08-09 10:14:10 -07:00
pnode.c
mnt: Add a per mount namespace limit on the number of mounts
2016-09-30 12:46:48 -05:00
pnode.h
mnt: Add a per mount namespace limit on the number of mounts
2016-09-30 12:46:48 -05:00
posix_acl.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2016-07-29 15:54:19 -07:00
proc_namespace.c
vfs: show_vfsstat: do not ignore errors from show_devname method
2016-03-16 13:09:08 -04:00
read_write.c
x86/syscalls: Add compat_sys_preadv64v2/compat_sys_pwritev64v2
2016-07-15 10:30:26 +02:00
readdir.c
restore killability of old mutex_lock_killable(&inode->i_mutex) users
2016-05-26 00:13:25 -04:00
select.c
fs: poll/select/recvmmsg: use timespec64 for timeout events
2016-05-19 19:12:14 -07:00
seq_file.c
fs/seq_file: fix out-of-bounds read
2016-08-26 17:39:35 -07:00
signalfd.c
signalfd: fix information leak in signalfd_copyinfo
2015-08-07 04:39:40 +03:00
splice.c
Merge branch 'ovl-fixes' into for-linus
2016-05-11 00:00:29 -04:00
stack.c
…
stat.c
fs/stat.c: drop the last new_valid_dev check
2016-01-16 11:17:23 -08:00
statfs.c
…
super.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2016-07-29 15:54:19 -07:00
sync.c
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros
2016-04-04 10:41:08 -07:00
timerfd.c
timerfd: Reject ALARM timerfds without CAP_WAKE_ALARM
2016-06-09 23:42:38 +02:00
userfaultfd.c
mm: introduce fault_env
2016-07-26 16:19:19 -07:00
utimes.c
fs: return EPERM on immutable inode
2016-08-07 10:03:31 -04:00
xattr.c
vfs: Don't modify inodes with a uid or gid unknown to the vfs
2016-07-05 15:06:46 -05:00