Hi,
This proposed change will collect all kernel modules in the
single directory, e.g. /lib/modules/2.6.29-rc2/kernel/, without
any further directory structure. About 475 inodes (with
almost-allmodconfig) less are used, which should result
in faster directory traversal (less seeks).
---8<---
parent 53c67f8b25a2e6b8b69ac235372cdda036070cfc (v2.6.29-rc2-22-g53c67f8)
commit 5e61b62737a2184742c4d63c9cdd6c5450ec4034
Author: Jan Engelhardt <[email protected]>
Date: Sat Jan 17 20:58:58 2009 +0100
kbuild: install to a single directory
Most of the directory hierarchy in /lib/modules/$(uname -r)/kernel/
seems redundant to me, so just collapse it all and stuff all files in
that single directory. No module name can be used twice anyway, so no
collision will occur.
Signed-off-by: Jan Engelhardt <[email protected]>
---
scripts/Makefile.modinst | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst
index 4c7c163..5b34e82 100644
--- a/scripts/Makefile.modinst
+++ b/scripts/Makefile.modinst
@@ -25,7 +25,7 @@ quiet_cmd_modules_install = INSTALL $@
INSTALL_MOD_DIR ?= extra
ext-mod-dir = $(INSTALL_MOD_DIR)$(subst $(patsubst %/,%,$(KBUILD_EXTMOD)),,$(@D))
-modinst_dir = $(if $(KBUILD_EXTMOD),$(ext-mod-dir),kernel/$(@D))
+modinst_dir = $(if $(KBUILD_EXTMOD),$(ext-mod-dir),kernel/)
$(modules):
$(call cmd,modules_install,$(MODLIB)/$(modinst_dir))
--
# Created with git-export-patch
Jan Engelhardt wrote:
> Hi,
>
> This proposed change will collect all kernel modules in the
> single directory, e.g. /lib/modules/2.6.29-rc2/kernel/, without
> any further directory structure. About 475 inodes (with
> almost-allmodconfig) less are used, which should result
> in faster directory traversal (less seeks).
While I agree that current deep-n-wide directory structure is
not very useful.. It still helps in many situations. For
example, I sometimes need to remember which module name this
particular scsi or network or [s]ata controller needs, and
looking at /lib/modules/$foo/kernel/driver/scsi is usually
sufficient since there isn't many of them in there. Or,
see (old, compat) -t option to modprobe(8).
In the other words, if to change anything at all, something
in-between is needed instead. No current deep-n-wide often
single-driver-in-directory structure, and not everything in
one place either.
Maybe add a make variable to tell kbuild to use specified
directory to install modules in this dir to, or to specify
that "this module should go to the parent dir" (eliminates
many driver-in-a-dir cases).
/mjt
On Sun, Jan 18, 2009 at 10:17:16PM +0100, Jan Engelhardt wrote:
> Hi,
>
>
>
> This proposed change will collect all kernel modules in the
> single directory, e.g. /lib/modules/2.6.29-rc2/kernel/, without
> any further directory structure. About 475 inodes (with
> almost-allmodconfig) less are used, which should result
> in faster directory traversal (less seeks).
Hi Jan.
Can you elaborate a little more why this is needed / a good thing.
Also:
-> Is mod-utils compatible with this change
-> Is userland in general compatible with this change
Sam
On Sun, 18 Jan 2009 22:17:16 +0100 (CET)
Jan Engelhardt <[email protected]> wrote:
> Hi,
>
>
>
> This proposed change will collect all kernel modules in the
> single directory, e.g. /lib/modules/2.6.29-rc2/kernel/, without
> any further directory structure. About 475 inodes (with
> almost-allmodconfig) less are used, which should result
> in faster directory traversal (less seeks).
What do your benchmark numbers look like ?
On Monday 2009-01-19 02:24, Sam Ravnborg wrote:
>On Sun, Jan 18, 2009 at 10:17:16PM +0100, Jan Engelhardt wrote:
>>
>> This proposed change will collect all kernel modules in the
>> single directory, e.g. /lib/modules/2.6.29-rc2/kernel/, without
>> any further directory structure. About 475 inodes (with
>> almost-allmodconfig) less are used, which should result
>> in faster directory traversal (less seeks).
>
>Can you elaborate a little more why this is needed / a good thing.
|[Alan Cox wants the numbers, too]
# File sizes (LZMA'ed RPM payload, but archive contains .ko.gz, so
# it is so-so~~)
-rw-r--r-- 1 31090287 Jan 19 10:51 kernel-2.6.29~rc2.i586.rpm
-rw-r--r-- 1 31031150 Jan 17 23:39 kernel-SingleDir-2.6.29~rc2.i586.rpm
# fs barriers are turned off (got an UPS)
# /tmp is XFS, on a 5400rpm disk on a 2003ish Athlon4 system, 768MB RAM
# installing rpm
md /tmp/test1/var/lib/rpm/;
for ((i = 0; i < 5; ++i)); do
rm -Rf /tmp/test1/var/lib/rpm/*;
rpm --root /tmp/test1 --initdb;
sync; echo 3 >/proc/sys/vm/drop_caches;
time ( rpm --root /tmp/test1 -ihv kernel-2.6.29~rc2.i586.rpm \
--nodeps --noscripts; sync; );
done
# kernel-2.6.29~rc2.i586.rpm
real 31.778 33.205 32.076 32.451 33.576
user 6.227 6.274 6.159 6.216 6.290
sys 1.837 1.806 1.888 1.890 1.843
# kernel-SingleDir-2.6.29~rc2.i586.rpm
real 18.666 19.257 19.013 19.257 19.280
user 6.222 6.225 6.232 6.245 6.270
sys 1.900 2.178 2.181 2.183 2.263
# running gzip -d for all .ko.gz
# running depmod
for ((i = 0; i < 5; ++i)); do
sync; echo 3 >/proc/sys/vm/drop_caches;
depmod -b /tmp/test1 -r 2.6.29-rc2;
done;
# depmod on kernel
real 32.256 32.242 32.275 32.392 32.529
user 2.004 2.029 2.034 2.051 1.963
sys 0.808 0.842 0.824 0.826 0.847
# depmod on kernel-SingleDir
real 21.062 19.293 19.326 19.411 19.361
user 1.691 1.693 1.660 1.724 1.760
sys 0.761 0.766 0.784 0.767 0.750
>Also:
>-> Is mod-utils compatible with this change
Yes, module-init-tools does not care about the directory layout --
how could it? If it depended such, m-i-t would have to be
adjusted on about every single new subsystem/directory that
is added.
>-> Is userland in general compatible with this change
More so than the .gz stuff, I'd say.