7.2. Profiles for file system performance

The tuned-adm tool allows users to easily swap between a number of profiles that have been designed to enhance performance for specific use cases. The profiles that are particularly useful in improving storage performance are:
latency-performance
A server profile for typical latency performance tuning. It disables tuned and ktune power-saving mechanisms. The cpuspeed mode changes to performance. The I/O elevator is changed to deadline for each device. The cpu_dma_latency parameter is registered with a value of 1 (the lowest possible latency) for power management quality-of-service to limit latency where possible.
throughput-performance
A server profile for typical throughput performance tuning. This profile is recommended if the system does not have enterprise-class storage. It is the same as latency-performance, except:
  • kernel.sched_min_granularity_ns (scheduler minimal preemption granularity) is set to 10 milliseconds,
  • kernel.sched_wakeup_granularity_ns (scheduler wake-up granularity) is set to 15 milliseconds,
  • vm.dirty_ratio (virtual memory dirty ratio) is set to 40%, and
  • transparent huge pages are enabled.
enterprise-storage
This profile is recommended for enterprise-sized server configurations with enterprise-class storage, including battery-backed controller cache protection and management of on-disk cache. It is the same as the throughput-performance profile, except:
  • readahead value is set to 4x, and
  • non root/boot file systems are re-mounted with barrier=0.
More information about tuned-adm is available on the man page (man tuned-adm), or in the Power Management Guide available from http://access.redhat.com/site/documentation/Red_Hat_Enterprise_Linux/.