On 18.08.2011 20:18, John Reiser wrote:
> Building an initramfs is unreasonably slow. On Fedora 16
> dracut-011 takes almost a minute when installing a new kernel:
> real 56s
> user 20s \__ dracut is CPU bound, not I/O bound.
> sys 31s /
Another profiling approach with dracut >= 013:
$ git clone git://git.kernel.org/pub/scm/boot/dracut/dracut.git
$ cd dracut
$ ./dracut --profile --local --force /tmp/test2.img &>/tmp/profile.out
$ python profile.py 2>/dev/null < /tmp/profile.out | head -10|sed 's#/.*/##g'
dracut-functions@287 24.6794755459
dracut-functions@864 19.2174339294
dracut-functions@286 12.4720790386
dracut-functions@284 12.4622004032
dracut-functions@285 12.3773012161
dracut-functions@326 7.45590758324
./dracut@653 6.62076878548
dracut-logger@334 6.58080339432
dracut-functions@315 6.04220032692
dracut-functions@863 4.97196722031
of course this method adds the time of the PS4 evaluation to every line. So if a
line is called often, the "date" call of
PS4='+ $(date "+%s.%N") ${BASH_SOURCE}@${LINENO}: '
is added multiple times.
Maybe we could patch bash to output nice profiling information.
lines 284-287 are in inst_dir()
dracut-functions@287 24.6794755459
dracut-functions@286 12.4720790386
dracut-functions@284 12.4622004032
dracut-functions@285 12.3773012161
This could, of course, be optimized. See attached patch.
Before:
real 0m30.752s
user 0m30.682s
sys 0m14.275s
After:
real 0m29.717s
user 0m30.486s
sys 0m14.220s
profiling after the patch:
dracut-functions@864 18.7074279785
dracut-functions@326 7.28814554214
./dracut@654 6.65880942345
dracut-logger@334 6.25012993813
dracut-functions@279 6.23409557343
dracut-functions@315 5.92809057236
dracut-functions@863 4.807523489
dracut-functions@862 4.75765013695
dracut-functions@411 3.63905620575
dracut-functions@273 3.21366071701
This is filter_kernel_modules()
dracut-functions@864 18.7074279785
dracut-functions@863 4.807523489
dracut-functions@862 4.75765013695
This is "cp -pfL":
dracut-functions@326 7.28814554214
This is the cpio and compress call:
./dracut@654 6.65880942345
diff --git a/dracut-functions b/dracut-functions
index 241d89a..d7f2e5f 100755
--- a/dracut-functions
+++ b/dracut-functions
@@ -274,18 +274,18 @@ inst_dir() {
local _oldifs="$IFS"
local _part
local _dir="$1"
- IFS="/"
- set -- $_dir
- IFS=$_oldifs
- _dir="$@"
+
+ # fast out
[[ -e ${initdir}$_dir ]] && return 0
- # iterate over parent directories
- for _part in $_dir; do
- [[ $_part ]] || continue
- _file="$_file/$_part"
- [[ -e ${initdir}$_file ]] && continue
+ _part=${_dir%/*}
+ while ! [[ -e "${initdir}${_part}" ]]; do
+ _dir="$_part $_dir"
+ _part=${_part%/*}
+ done
+ # iterate over parent directories
+ for _file in $_dir; do
if [[ -L $_file ]]; then
# create link as the original
local target=$(readlink -f "$_file")
