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Revision 59a32e2ce5eb809967cac4e718bc527beca83c59 authored by Eric Dumazet on 23 March 2012, 22:02:53 UTC, committed by Linus Torvalds on 23 March 2012, 23:58:42 UTC 
proc: speed up /proc/stat handling
 
On a typical 16 cpus machine, "cat /proc/stat" gives more than 4096 bytes,
and is slow :

  # strace -T -o /tmp/STRACE cat /proc/stat | wc -c
  5826
  # grep "cpu " /tmp/STRACE
  read(0, "cpu  1949310 19 2144714 12117253"..., 32768) = 5826 <0.001504>

Thats partly because show_stat() must be called twice since initial
buffer size is too small (4096 bytes for less than 32 possible cpus)

Fix this by :

 1) Taking into account nr_irqs in the initial buffer sizing.

 2) Using ksize() to allow better filling of initial buffer.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent b908243
Raw File
Makefile.modbuiltin 
# ==========================================================================
# Generating modules.builtin
# ==========================================================================

src := $(obj)

PHONY := __modbuiltin
__modbuiltin:

-include include/config/auto.conf
# tristate.conf sets tristate variables to uppercase 'Y' or 'M'
# That way, we get the list of built-in modules in obj-Y
-include include/config/tristate.conf

include scripts/Kbuild.include

ifneq ($(KBUILD_SRC),)
# Create output directory if not already present
_dummy := $(shell [ -d $(obj) ] || mkdir -p $(obj))
endif

# The filename Kbuild has precedence over Makefile
kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
include $(kbuild-file)

include scripts/Makefile.lib
__subdir-Y     := $(patsubst %/,%,$(filter %/, $(obj-Y)))
subdir-Y       += $(__subdir-Y)
subdir-ym      := $(sort $(subdir-y) $(subdir-Y) $(subdir-m))
subdir-ym      := $(addprefix $(obj)/,$(subdir-ym))
obj-Y          := $(addprefix $(obj)/,$(obj-Y))

modbuiltin-subdirs := $(patsubst %,%/modules.builtin, $(subdir-ym))
modbuiltin-mods    := $(filter %.ko, $(obj-Y:.o=.ko))
modbuiltin-target  := $(obj)/modules.builtin

__modbuiltin: $(modbuiltin-target) $(subdir-ym)
	@:

$(modbuiltin-target): $(subdir-ym) FORCE
	$(Q)(for m in $(modbuiltin-mods); do echo kernel/$$m; done;	\
	cat /dev/null $(modbuiltin-subdirs)) > $@

PHONY += FORCE

FORCE:

# Descending
# ---------------------------------------------------------------------------

PHONY += $(subdir-ym)
$(subdir-ym):
	$(Q)$(MAKE) $(modbuiltin)=$@


# Declare the contents of the .PHONY variable as phony.  We keep that
# information in a variable se we can use it in if_changed and friends.

.PHONY: $(PHONY)
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