| Christoph Lameter | 5912100 | 2005-06-23 00:08:25 -0700 | [diff] [blame] | 1 | # |
| 2 | # Timer Interrupt Frequency Configuration |
| 3 | # |
| 4 | |
| 5 | choice |
| 6 | prompt "Timer frequency" |
| 7 | default HZ_250 |
| 8 | help |
| 9 | Allows the configuration of the timer frequency. It is customary |
| Alan Cox | 40fcfc8 | 2006-12-06 20:37:27 -0800 | [diff] [blame] | 10 | to have the timer interrupt run at 1000 Hz but 100 Hz may be more |
| Christoph Lameter | 5912100 | 2005-06-23 00:08:25 -0700 | [diff] [blame] | 11 | beneficial for servers and NUMA systems that do not need to have |
| 12 | a fast response for user interaction and that may experience bus |
| 13 | contention and cacheline bounces as a result of timer interrupts. |
| 14 | Note that the timer interrupt occurs on each processor in an SMP |
| 15 | environment leading to NR_CPUS * HZ number of timer interrupts |
| 16 | per second. |
| 17 | |
| 18 | |
| 19 | config HZ_100 |
| 20 | bool "100 HZ" |
| 21 | help |
| Alan Cox | 40fcfc8 | 2006-12-06 20:37:27 -0800 | [diff] [blame] | 22 | 100 Hz is a typical choice for servers, SMP and NUMA systems |
| Christoph Lameter | 5912100 | 2005-06-23 00:08:25 -0700 | [diff] [blame] | 23 | with lots of processors that may show reduced performance if |
| 24 | too many timer interrupts are occurring. |
| 25 | |
| 26 | config HZ_250 |
| 27 | bool "250 HZ" |
| 28 | help |
| Alan Cox | 40fcfc8 | 2006-12-06 20:37:27 -0800 | [diff] [blame] | 29 | 250 Hz is a good compromise choice allowing server performance |
| Christoph Lameter | 5912100 | 2005-06-23 00:08:25 -0700 | [diff] [blame] | 30 | while also showing good interactive responsiveness even |
| Alan Cox | 40fcfc8 | 2006-12-06 20:37:27 -0800 | [diff] [blame] | 31 | on SMP and NUMA systems. If you are going to be using NTSC video |
| 32 | or multimedia, selected 300Hz instead. |
| 33 | |
| 34 | config HZ_300 |
| 35 | bool "300 HZ" |
| 36 | help |
| 37 | 300 Hz is a good compromise choice allowing server performance |
| 38 | while also showing good interactive responsiveness even |
| 39 | on SMP and NUMA systems and exactly dividing by both PAL and |
| 40 | NTSC frame rates for video and multimedia work. |
| Christoph Lameter | 5912100 | 2005-06-23 00:08:25 -0700 | [diff] [blame] | 41 | |
| 42 | config HZ_1000 |
| 43 | bool "1000 HZ" |
| 44 | help |
| Alan Cox | 40fcfc8 | 2006-12-06 20:37:27 -0800 | [diff] [blame] | 45 | 1000 Hz is the preferred choice for desktop systems and other |
| Christoph Lameter | 5912100 | 2005-06-23 00:08:25 -0700 | [diff] [blame] | 46 | systems requiring fast interactive responses to events. |
| 47 | |
| 48 | endchoice |
| 49 | |
| 50 | config HZ |
| 51 | int |
| 52 | default 100 if HZ_100 |
| 53 | default 250 if HZ_250 |
| Alan Cox | 40fcfc8 | 2006-12-06 20:37:27 -0800 | [diff] [blame] | 54 | default 300 if HZ_300 |
| Christoph Lameter | 5912100 | 2005-06-23 00:08:25 -0700 | [diff] [blame] | 55 | default 1000 if HZ_1000 |
| 56 | |
| Peter Zijlstra | 8f4d37e | 2008-01-25 21:08:29 +0100 | [diff] [blame] | 57 | config SCHED_HRTICK |
| OGAWA Hirofumi | 94f5655 | 2008-07-27 20:27:06 +0900 | [diff] [blame] | 58 | def_bool HIGH_RES_TIMERS && (!SMP || USE_GENERIC_SMP_HELPERS) |