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1ac101a5d6
linux/lib
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KAMEZAWA Hiroyuki 1ac101a5d6 procfs: add num_to_str() to speed up /proc/stat 
== stat_check.py
num = 0
with open("/proc/stat") as f:
        while num < 1000 :
                data = f.read()
                f.seek(0, 0)
                num = num + 1
==

perf shows

    20.39%  stat_check.py  [kernel.kallsyms]    [k] format_decode
    13.41%  stat_check.py  [kernel.kallsyms]    [k] number
    12.61%  stat_check.py  [kernel.kallsyms]    [k] vsnprintf
    10.85%  stat_check.py  [kernel.kallsyms]    [k] memcpy
     4.85%  stat_check.py  [kernel.kallsyms]    [k] radix_tree_lookup
     4.43%  stat_check.py  [kernel.kallsyms]    [k] seq_printf

This patch removes most of calls to vsnprintf() by adding num_to_str()
and seq_print_decimal_ull(), which prints decimal numbers without rich
functions provided by printf().

On my 8cpu box.
== Before patch ==
[root@bluextal test]# time ./stat_check.py

real    0m0.150s
user    0m0.026s
sys     0m0.121s

== After patch ==
[root@bluextal test]# time ./stat_check.py

real    0m0.055s
user    0m0.022s
sys     0m0.030s

[akpm@linux-foundation.org: remove incorrect comment, use less statck in num_to_str(), move comment from .h to .c, simplify seq_put_decimal_ull()]
[andrea@betterlinux.com: avoid breaking the ABI in /proc/stat]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrea Righi <andrea@betterlinux.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Turner <pjt@google.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-23 16:58:42 -07:00
..
lzo lib: add support for LZO-compressed kernels 2010-01-11 09:34:04 -08:00
mpi lib: Fix 32-bit sparc udiv_qrnnd() definition in mpilib's longlong.h 2012-02-02 10:34:25 +11:00
raid6 md: Add in export.h for files using EXPORT_SYMBOL 2011-10-31 19:31:19 -04:00
reed_solomon
xz XZ: Fix incorrect XZ_BUF_ERROR 2011-09-21 13:39:59 -07:00
zlib_deflate zlib: slim down zlib_deflate() workspace when possible 2011-03-22 17:44:17 -07:00
zlib_inflate inflate_fast: sout is already a short so ptr arith was off by one. 2010-03-12 15:52:44 -08:00
.gitignore
argv_split.c tree-wide: convert open calls to remove spaces to skip_spaces() lib function 2009-12-15 08:53:32 -08:00
atomic64_test.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
atomic64.c lib: atomic64: Change the type of local lock to raw_spinlock_t 2011-09-14 13:14:11 +02:00
audit.c audit: support the "standard" <asm-generic/unistd.h> 2011-05-04 14:41:28 -04:00
average.c lib: Improve EWMA efficiency by using bitshifts 2010-12-06 15:58:43 -05:00
bcd.c
bch.c lib: add shared BCH ECC library 2011-03-11 14:25:50 +00:00
bitmap.c lib/bitmap.c: quiet sparse noise about address space 2011-10-31 17:30:56 -07:00
bitrev.c
bsearch.c lib: Add generic binary search function to the kernel. 2011-05-19 16:55:27 +09:30
btree.c btree: export btree_get_prev() so modules can use btree_for_each 2012-01-10 16:30:49 -08:00
bug.c bugs, x86: Fix printk levels for panic, softlockups and stack dumps 2012-01-26 21:28:45 +01:00
bust_spinlocks.c
check_signature.c
checksum.c lib/checksum.c: optimize do_csum a bit 2011-07-07 04:52:24 -07:00
clz_tab.c lib: Fix multiple definitions of clz_tab 2012-02-02 10:34:23 +11:00
cmdline.c
cordic.c Docs: wording: functions -> algorithm 2011-10-29 21:20:22 +02:00
cpu_rmap.c lib: cpu_rmap: CPU affinity reverse-mapping 2011-01-24 14:51:56 -08:00
cpu-notifier-error-inject.c fault-injection: add CPU notifier error injection module 2010-05-27 09:12:48 -07:00
cpumask.c cpumask: alloc_cpumask_var() use NUMA_NO_NODE 2011-07-26 16:49:44 -07:00
crc7.c
crc8.c lib: crc8: add new library module providing crc8 algorithm 2011-06-03 15:01:06 -04:00
crc16.c
crc32.c crc32: add self-test code for crc32c 2012-03-23 16:58:38 -07:00
crc32defs.h crc32: select an algorithm via Kconfig 2012-03-23 16:58:38 -07:00
crc-ccitt.c
crc-itu-t.c
crc-t10dif.c
ctype.c ctype: constify read-only _ctype string 2009-12-15 08:53:32 -08:00
debug_locks.c Revert "debug_locks: set oops_in_progress if we will log messages." 2010-11-29 15:18:28 -08:00
debugobjects.c debugobjects: Fix selftest for static warnings 2012-03-05 15:49:43 -08:00
dec_and_lock.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
decompress_bunzip2.c decompress_bunzip2: remove invalid vi modeline 2011-12-06 10:00:05 +01:00
decompress_inflate.c decompressors: check input size in decompress_inflate.c 2011-01-13 08:03:25 -08:00
decompress_unlzma.c treewide: Fix comment and string typo 'bufer' 2011-12-06 09:53:40 +01:00
decompress_unlzo.c unlzo: fix input buffer free 2012-01-12 20:13:13 -08:00
decompress_unxz.c Fix common misspellings 2011-03-31 11:26:23 -03:00
decompress.c decompressors: add boot-time XZ support 2011-01-13 08:03:25 -08:00
devres.c Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci 2012-01-11 18:50:26 -08:00
digsig.c lib/digsig: checks for NULL return value 2012-02-02 00:24:04 +11:00
div64.c div64_u64(): improve precision on 32bit platforms 2010-10-26 16:52:19 -07:00
dma-debug.c Remove useless get_driver()/put_driver() calls 2012-01-24 16:00:35 -08:00
dump_stack.c
dynamic_debug.c dynamic_debug: process multiple debug-queries on a line 2012-01-24 12:50:36 -08:00
dynamic_queue_limits.c dql: Fix undefined jiffies 2012-03-11 19:59:43 -07:00
extable.c
fault-inject.c switch debugfs to umode_t 2012-01-03 22:54:56 -05:00
find_last_bit.c bitops: add #ifndef for each of find bitops 2011-05-26 17:12:38 -07:00
find_next_bit.c arch: remove CONFIG_GENERIC_FIND_{NEXT_BIT,BIT_LE,LAST_BIT} 2011-05-26 17:12:38 -07:00
flex_array.c flex_array: avoid divisions when accessing elements 2011-05-26 17:12:33 -07:00
gcd.c
gen_crc32table.c crc32: bolt on crc32c 2012-03-23 16:58:38 -07:00
genalloc.c lib, Make gen_pool memory allocator lockless 2011-08-03 11:15:57 -04:00
halfmd4.c
hexdump.c lib: add error checking to hex2bin 2011-09-20 23:24:44 -04:00
hweight.c x86: Add optimized popcnt variants 2010-04-06 15:52:11 -07:00
idr.c idr: make idr_get_next() good for rcu_read_lock() 2012-03-21 17:55:01 -07:00
inflate.c MN10300: Don't try and #include <linux/slab.h> in lib/inflate.c from bootloader 2010-08-12 09:51:35 -07:00
int_sqrt.c
iomap_copy.c
iomap.c lib: add GENERIC_PCI_IOMAP 2011-11-28 21:12:42 +02:00
iommu-helper.c iommu: inline iommu_num_pages 2010-08-09 20:45:05 -07:00
ioremap.c ACPI, APEI, Generic Hardware Error Source POLL/IRQ/NMI notification type support 2011-01-12 03:06:19 -05:00
irq_regs.c
is_single_threaded.c
kasprintf.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
Kconfig crc32: select an algorithm via Kconfig 2012-03-23 16:58:38 -07:00
Kconfig.debug nmi watchdog: do not use cpp symbol in Kconfig 2012-03-23 16:58:31 -07:00
Kconfig.kgdb mips,kgdb: kdb low level trap catch and stack trace 2010-05-20 21:04:26 -05:00
Kconfig.kmemcheck
klist.c
kobject_uevent.c uevent: send events in correct order according to seqnum (v3) 2012-03-08 12:56:40 -08:00
kobject.c kobject: remove kset_find_obj_hinted() 2011-12-21 15:13:54 -08:00
kstrtox.c Reduce the number of expensive division instructions done by _parse_integer() 2012-02-09 10:09:30 -08:00
kstrtox.h lib/kstrtox: common code between kstrto*() and simple_strto*() functions 2011-10-31 17:30:56 -07:00
lcm.c lib/lcm.c: quiet sparse noise 2011-07-25 20:57:15 -07:00
libcrc32c.c
list_debug.c Expand CONFIG_DEBUG_LIST to several other list operations 2011-02-18 11:32:28 -08:00
list_sort.c lib/list_sort: test: check element addresses 2010-10-26 16:52:19 -07:00
llist.c llist: Remove cpu_relax() usage in cmpxchg loops 2011-10-04 12:44:03 +02:00
locking-selftest-hardirq.h
locking-selftest-mutex.h
locking-selftest-rlock-hardirq.h
locking-selftest-rlock-softirq.h
locking-selftest-rlock.h
locking-selftest-rsem.h
locking-selftest-softirq.h
locking-selftest-spin-hardirq.h
locking-selftest-spin-softirq.h
locking-selftest-spin.h
locking-selftest-wlock-hardirq.h
locking-selftest-wlock-softirq.h
locking-selftest-wlock.h
locking-selftest-wsem.h
locking-selftest.c rcu: Fix unpaired rcu_irq_enter() from locking selftests 2011-05-26 09:42:19 -07:00
lru_cache.c lru_cache: use correct type in sizeof for allocation 2011-05-25 08:39:52 -07:00
Makefile lib: Fix multiple definitions of clz_tab 2012-02-02 10:34:23 +11:00
md5.c crypto: Move md5_transform to lib/md5.c 2011-08-06 18:32:45 -07:00
nlattr.c netlink: validate NLA_MSECS length 2011-11-04 17:47:34 -04:00
parser.c Fix common misspellings 2011-03-31 11:26:23 -03:00
pci_iomap.c lib: add NO_GENERIC_PCI_IOPORT_MAP 2012-01-31 23:19:47 +02:00
percpu_counter.c lib/percpu_counter.c: enclose hotplug only variables in hotplug ifdef 2011-10-31 17:30:56 -07:00
plist.c plist: Remove the need to supply locks to plist heads 2011-07-08 14:02:53 +02:00
prio_heap.c
prio_tree.c prio_tree: introduce prio_set_parent() 2012-03-23 16:58:36 -07:00
proportions.c locking, lib/proportions: Annotate prop_local_percpu::lock as raw 2011-09-13 11:11:50 +02:00
radix-tree.c radix_tree: take radix_tree_path off stack 2012-01-12 20:13:12 -08:00
random32.c Merge branch 'master' into for-next 2010-06-16 18:08:13 +02:00
ratelimit.c locking, printk: Annotate logbuf_lock as raw 2011-09-13 11:11:54 +02:00
rational.c lib/rational.c needs module.h 2010-01-11 09:34:05 -08:00
rbtree.c Export the augmented rbtree helper functions 2011-01-28 12:16:59 +10:00
reciprocal_div.c sch_red: Adaptative RED AQM 2011-12-08 19:52:43 -05:00
rwsem-spinlock.c locking, rwsem: Annotate inner lock as raw 2011-09-13 11:11:59 +02:00
rwsem.c locking, rwsem: Annotate inner lock as raw 2011-09-13 11:11:59 +02:00
scatterlist.c lib: remove the second argument of k[un]map_atomic() 2012-03-20 21:48:27 +08:00
sha1.c lib/sha1.c: quiet sparse noise about symbol not declared 2011-09-13 16:09:41 -07:00
show_mem.c arch, mm: filter disallowed nodes from arch specific show_mem functions 2011-05-25 08:39:03 -07:00
smp_processor_id.c sched: Wrap scheduler p->cpus_allowed access 2011-10-06 12:46:56 +02:00
sort.c
spinlock_debug.c lib/spinlock_debug.c: print owner on spinlock lockup 2011-10-31 17:30:56 -07:00
string_helpers.c
string.c string: memchr_inv() speed improvements 2012-03-23 16:58:35 -07:00
swiotlb.c lib: remove the second argument of k[un]map_atomic() 2012-03-20 21:48:27 +08:00
syscall.c
test-kstrtox.c kstrtox: fix compile warnings in test 2011-04-14 16:06:54 -07:00
textsearch.c textsearch: doc - fix spelling in lib/textsearch.c. 2011-01-24 23:33:30 -08:00
timerqueue.c Fix common misspellings 2011-03-31 11:26:23 -03:00
ts_bm.c
ts_fsm.c
ts_kmp.c
uuid.c Unified UUID/GUID definition 2010-05-19 22:40:47 -04:00
vsprintf.c procfs: add num_to_str() to speed up /proc/stat 2012-03-23 16:58:42 -07:00