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Repository for eudev development
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I noticed a comment in namedev.c which stated "Figure out where the device symlink is at. For char devices this will always be in the class_dev->path. But for block devices, it's different. The main block device will have the device symlink in it's path, but all partitions have the symlink in its parent directory. But we need to watch out for block devices that do not have parents, yet look like a partition (fd0, loop0, etc.). They all do not have a device symlink yet. We do a sit and spin on waiting for them right now, we should possibly have a whitelist for these devices here..." I went ahead and created a whitelist for the block devices that look like partitions (mainly by using devices.txt) and tested for any performance increase that we would see. The whitelist only impacts udevstart time depending on the state of UDEV_NO_SLEEP. Since the list was short, I just did a sequential search and ordered the list in such a way that those block devices which have more /dev entires (ex. loop0, loop1, loop2, etc) appear sooner in the list and will thus be found quicker. I've enclosed the patch and some of the performance results I saw below. Basically, as the number of block devices without device symlinks increased, the use of the whitelist improved udevstart performance compared to just sitting and spinning. I just thought it was interesting and thought I'd share. If you feel the patch is beneficial please consider for merging. Also, if you'd be interested in expanding the whitelist for other devices which are missing device symlinks and seeing if there are added performance increases let me know and I'll do what I can. Thanks, Leann Note: ex. loop represents all the loop devices (i.e. loop0, loop1, loop2, etc) block devices present with whitelist time |
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docs | ||
etc | ||
extras | ||
klibc | ||
libsysfs | ||
tdb | ||
test | ||
ChangeLog | ||
COPYING | ||
dev_d.c | ||
FAQ | ||
HOWTO-udev_for_dev | ||
klibc_fixups.c | ||
klibc_fixups.h | ||
list.h | ||
logging.h | ||
make_gcov.sh | ||
Makefile | ||
namedev_parse.c | ||
namedev.c | ||
namedev.h | ||
README | ||
README-gcov_for_udev | ||
run_gcov.sh | ||
TODO | ||
udev_config.c | ||
udev_lib.c | ||
udev_lib.h | ||
udev-add.c | ||
udev-remove.c | ||
udev.8.in | ||
udev.c | ||
udev.h | ||
udev.spec | ||
udevd.8 | ||
udevd.c | ||
udevd.h | ||
udevdb.c | ||
udevdb.h | ||
udevinfo.8 | ||
udevinfo.c | ||
udevruler.c | ||
udevsend.c | ||
udevstart.8 | ||
udevstart.c | ||
udevtest.8 | ||
udevtest.c |
udev - a userspace implementation of devfs For more information on the design, and structure of this project, see the files in the docs/ directory. To use: - You must be running a 2.6 version of the Linux kernel. - Your 2.6 kernel must have had CONFIG_HOTPLUG enabled when it was built. - Make sure sysfs is mounted. udev will figure out where sysfs is mounted, but the traditional place for it is at /sys. You can mount it by hand by running: mount -t sysfs none /sys - Make sure you have the latest version of the linux-hotplug scripts. They are available at linux-hotplug.sf.net or from your local kernel.org mirror at: kernel.org/pub/linux/utils/kernel/hotplug/ They are required in order for udev to work properly. If for some reason you do not install the hotplug scripts, you must tell the kernel to point the hotplug binary at wherever you install udev at. This can be done by: echo "/sbin/udev" > /proc/sys/kernel/hotplug - Build the project: make Note: There are a number of different flags that you can use when building udev. They are as follows: prefix set this to the default root that you want udev to be installed into. This works just like the 'configure --prefix' script does. Default value is ''. Only override this if you really know what you are doing. USE_KLIBC if set to 'true', udev is built and linked against the included version of klibc. Default value is 'false'. USE_LOG if set to 'true', udev will emit messages to the syslog when it creates or removes device nodes. This is helpful to see what udev is doing. This is enabled by default. Note, if you are building udev against klibc it is recommended that you disable this option (due to klibc's syslog implementation.) DEBUG if set to 'true', debugging messages will be sent to the syslog as udev is run. Default value is 'false'. KERNEL_DIR If this is not set it will default to /lib/modules/`uname -r`/build This is used if USE_KLIBC=true to find the kernel include directory that klibc needs to build against. This must be set if you are not building udev while running a 2.6 kernel. So, if you want to build udev using klibc with debugging messages, you would do: make USE_KLIBC=true DEBUG=true - Install the project: make install This will put the udev binary in /sbin, create the /udev and /etc/udev directories, and place the udev configuration files in /etc/udev. You will probably want to edit the namedev.* files to create custom naming rules. More info on how the config files are set up are contained in comments in the files, and is located in the documentation. - Add and remove devices from the system and marvel as nodes are created and removed in /udev/ based on the device types. - If you later get sick of it, uninstall it: make uninstall Things are still quite rough, but it should work properly. If nothing seems to happen, make sure your build worked properly by running the udev-test.pl script as root in the test/ subdirectory of the udev source tree. Development and documentation help is very much appreciated, see the TODO file for a list of things left to be done. Any comment/questions/concerns please let me and the other udev developers know by sending a message to the linux-hotplug-devel mailing list at: linux-hotplug-devel@lists.sourceforge.net greg k-h greg@kroah.com