This script will test performance of 'ip netns exec <ns> /bin/true" when increasing namespaces by 1000.
** Attachment added: "test_ns.sh" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1226726/+attachment/3825692/+files/test_ns.sh ** Also affects: linux (Ubuntu Precise) Importance: Undecided Status: New ** Also affects: linux (Ubuntu Quantal) Importance: Undecided Status: New ** Also affects: linux (Ubuntu Saucy) Importance: Medium Assignee: Chris J Arges (arges) Status: New ** Also affects: linux (Ubuntu Raring) Importance: Undecided Status: New ** Changed in: linux (Ubuntu Raring) Assignee: (unassigned) => Chris J Arges (arges) ** Changed in: linux (Ubuntu Quantal) Assignee: (unassigned) => Chris J Arges (arges) ** Changed in: linux (Ubuntu Precise) Assignee: (unassigned) => Chris J Arges (arges) ** Changed in: linux (Ubuntu Precise) Importance: Undecided => Medium ** Changed in: linux (Ubuntu Quantal) Importance: Undecided => Medium ** Changed in: linux (Ubuntu Raring) Importance: Undecided => Medium ** Changed in: linux (Ubuntu Saucy) Importance: Medium => Undecided ** Changed in: linux (Ubuntu Saucy) Assignee: Chris J Arges (arges) => (unassigned) ** Changed in: linux (Ubuntu Saucy) Status: New => Fix Released ** Changed in: linux (Ubuntu Precise) Status: New => In Progress ** Changed in: linux (Ubuntu Quantal) Status: New => In Progress ** Changed in: linux (Ubuntu Raring) Status: New => In Progress -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1226726 Title: dentry_reset_mounted walks entire mount list holding vfsmount write lock Status in “linux” package in Ubuntu: Fix Released Status in “linux” source package in Precise: In Progress Status in “linux” source package in Quantal: In Progress Status in “linux” source package in Raring: In Progress Status in “linux” source package in Saucy: Fix Released Bug description: Whenever one enters a network namespace via "ip netns exec foobar somecommand" there is a mount done of the appropriate device on /sys since "somecommand" needs to see namespace specific versions of /sys directories. When the ip process exits these mounts need to be torn down, and that requires a global write lock for vfsmount_lock (this is a single writer multiple reader lock). This has serious performance implications when the number of name spaces increase. The commit 84d17192 addresses this issue, and it is clear by running the attached testcase that it fixes performance issues when dealing with large numbers of namespaces. I've included a graph with the differences in performance between this fix and its parent commit to show the the improve in performance. The x-axis represents the number of namespaces and the y-axis is execution time in ms. After applying the patch the performance delays are not exponentially increasing. This affects 3.2/3.5/3.8 series kernels, as it was fixed in 3.10. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1226726/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp