From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Date: Sat, 23 Oct 2004 05:41:19 +0000 Subject: udev hangs under high loads Message-Id: <20041023054119.GA11915@kroah.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-hotplug@vger.kernel.org One of my coworkers (hi Nish) is trying to get 10000 disk support tested and working properly with linux and ran into a nasty udev issue yesterday. It seems that under a very high load, with a whole bunch of hotplug events happening (for when the disks get added to the system), udev hangs. It hangs in the "grabbing the database lock" portion of the code (don't have actual logs of where it hangs, will try to get that next week.) But the interesting thing is we almost handle everything properly. udev creates the node, tries to write to the database. Then the timer expires and we report this. After the timer expires, udev is done for. It just sits and spins, doing a nanosleep constantly. Have 500 of those instances all running at once, all at a nice level of -10 is a sure way to bring a box (even a relatively big one) down hard. So, while I'll agree finding the root tdb locking bug is a good idea, I wanted to point out that perhaps we should just exit udev if our timeout expires, instead of still waiting around. Or do you have a better solution? Try testing this out on your own using the scsi_debug module and adding a few hundred disks. It also helps if you have scsi generic support enabled, as that creates 2 udev events for every disk created. thanks, greg k-h ------------------------------------------------------- This SF.net email is sponsored by: IT Product Guide on ITManagersJournal Use IT products in your business? Tell us what you think of them. Give us Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more http://productguide.itmanagersjournal.com/guidepromo.tmpl _______________________________________________ Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net Linux-hotplug-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel