Updated tuned packages that fix several bugs and add one enhancement are now available for Red Hat Enterprise Linux 6.
The tuned packages contain a daemon that tunes system settings dynamically. It does so by monitoring the usage of several system components periodically.
- Previously, when multiple devices were added into the system, a udev rule restarted the ktune service for each new device. This could lead to many restarts in a short period of time. The multiple restarts could trigger a race condition in the kernel, which cannot be currently fixed. The tuned daemon code has been modified not to trigger more than one restart per 10 seconds, thus preventing the race condition from occurring.
- The kernel.sched_migration_cost tunable was previously kept at its default value of 0.5 ms. As a consequence, big virtualization hosts could experience high contention at the run queue lock. With this update, the kernel.sched_migration_cost tunable has been increased 10 times in the virtual-host profile, which eliminates the contention.
- Previously, the ktune service did not save readahead values. On startup, it multiplied the current value by a constant and divided the value by the same constant on stop. This could result in a wrong value being set on devices that were added after ktune had been started. Now, the previous readahead values are stored for all devices and the correct values are restored on ktune stop.
- Previously, the tuned utility did not support the upstream /sys/kernel/mm/transparent_hugepage location for Transparent Huge Pages (THP). The code has been modified and support for the SYSFS path used by upstream has been added. Tuned now supports the aforementioned upstream path as well as the Red Hat Enterprise Linux specific one.
- There was a typo in the USB autosuspend code and also an old non-functional code in the function that handles Bluetooth. As a consequence, various errors occurred when the user activated the spindown-disk profile. The typo has been fixed and the Bluetooth code has been updated. As a result, errors no longer occur when the spindown-disk profile is activated.
- Previously, the mount command was used to remount file systems with the "no_barriers" option, but not all file systems could be remounted. As a consequence, the remount occasionally failed displaying an error message, which could confuse users. With this update, the error messages from the mount command have been silenced. Now, if the file system cannot be remounted with no_barriers, it is silently skipped and no error is displayed.
- Previously, the sysctl utility was loaded and the shell script was run before the elevator was changed. As a consequence, the user was unable to change or tune the elevator parameters. The code has been reordered to load sysctl and run the shell script after the elevator has been changed. As a result, the user can now tune the elevator parameters.
- The diskdevstat and netdevstat code was not consistent in naming the parameters in the built-in help. The terms "total-duration" and "total-interval" have been used to denote the same thing. With this update, the text has been updated to be consistent and now, only the "total-duration" string is used.
- Previously ktune did not handle the /etc/sysctl.d/ directory and did not support multiple files with sysctl settings. As a consequence, the settings that several packages, for example libvirt, installed in the /etc/sysctl.d directory, were ignored. Ater this update, the ktune code and profiles have been modified. Now all sysctl settings in the /etc/sysctl.d/ directory are loaded and then the /etc/sysctl.conf file is loaded. The user can now specify multiple sysctl files, including wildcards, to load in the tuned profiles.
- Previously, there was no documentation for the Tuned virtual-guest and virtual-host profiles. Descriptions for these profiles have been added to the tuned-adm manual page.
- Previously, there was an typo in the built-in help of the tuned-adm command. The text mentioned "tunning" instead of "tuning", in the description of tuned-adm. This update fixes the typo in the built-in help.
- Tuned previously locked the CPU to the C0 state in the latency-performance profile. With this update, the latency-performance profile has been modified to use the C1 state by default, thus improving the performance of the profile.
- This update adds the "sapconf" package to the Tuned utility. The tuned-adm "sap" profile is used то optimize systems running SAP software, matching the relevant SAP guidelines.
Users of tuned are advised to upgrade to these updated packages, which fix these bugs and add this enhancement.