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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
depmod.sh 
#!/bin/sh
#
# A depmod wrapper used by the toplevel Makefile

if test $# -ne 2; then
	echo "Usage: $0 /sbin/depmod <kernelrelease>" >&2
	exit 1
fi
DEPMOD=$1
KERNELRELEASE=$2

if ! test -r System.map -a -x "$DEPMOD"; then
	exit 0
fi
# older versions of depmod require the version string to start with three
# numbers, so we cheat with a symlink here
depmod_hack_needed=true
tmp_dir=$(mktemp -d ${TMPDIR:-/tmp}/depmod.XXXXXX)
mkdir -p "$tmp_dir/lib/modules/$KERNELRELEASE"
if "$DEPMOD" -b "$tmp_dir" $KERNELRELEASE 2>/dev/null; then
	if test -e "$tmp_dir/lib/modules/$KERNELRELEASE/modules.dep" -o \
		-e "$tmp_dir/lib/modules/$KERNELRELEASE/modules.dep.bin"; then
		depmod_hack_needed=false
	fi
fi
rm -rf "$tmp_dir"
if $depmod_hack_needed; then
	symlink="$INSTALL_MOD_PATH/lib/modules/99.98.$KERNELRELEASE"
	ln -s "$KERNELRELEASE" "$symlink"
	KERNELRELEASE=99.98.$KERNELRELEASE
fi

set -- -ae -F System.map
if test -n "$INSTALL_MOD_PATH"; then
	set -- "$@" -b "$INSTALL_MOD_PATH"
fi
"$DEPMOD" "$@" "$KERNELRELEASE"
ret=$?

if $depmod_hack_needed; then
	rm -f "$symlink"
fi

exit $ret
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