Red Hat Bugzilla – Bug 1018474
Can't set vm.nr_pdflush_threads= variable from kernel
Last modified: 2013-10-12 08:42:29 EDT
Description of problem: Version-Release number of selected component (if applicable): kernel 3.11.1-200.fc19.x86_64 How reproducible: Steps to Reproduce: 1.Run as root sysctl -w vm.nr_pdflush_threads=1 2.sysctl -a 3. Actual results: Variable vm.nr_pdflush_threads=0 Expected results: vm.nr_pdflush_threads=1 Additional info:
That's because it's been obsolete for a while. per-BDI flusher threads were introduced in 2.6 and pdflush isn't used anymore. In 3.6, the following commit made the nr_pdflush_threads sysctl obsolete: commit 3965c9ae47d64aadf6f13b6fcd37767b83c0689a Author: Wanpeng Li <liwp@linux.vnet.ibm.com> Date: Tue Jul 31 16:41:52 2012 -0700 mm: prepare for removal of obsolete /proc/sys/vm/nr_pdflush_threads Since per-BDI flusher threads were introduced in 2.6, the pdflush mechanism is not used any more. But the old interface exported through /proc/sys/vm/nr_pdflush_threads still exists and is obviously useless. For back-compatibility, printk warning information and return 2 to notify the users that the interface is removed. Signed-off-by: Wanpeng Li <liwp@linux.vnet.ibm.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>