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| 1 | cpumask: set nr_cpumask_bits to nr_cpu_ids on PREEMPT_RT | |
| 2 | ||
| 3 | As we have CPUMASK_OFFSTACK disabled on RT, we end up having the cpumap | |
| 4 | and cpumask set with the full NR_CPUS size, 5120 bits. That causes | |
| 5 | /sys/devices/system/node/nodeX/cpumap to display a huge array of values | |
| 6 | instead of the cpumap containing the amount of CPUs supported by the system. | |
| 7 | ||
| 8 | Example: | |
| 9 | ||
| 10 | # cat /sys/devices/system/node/node0/cpumap | |
| 11 | 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,0000000f | |
| 12 | ||
| 13 | With CPUMASK_OFFSTACK enabled we would have: | |
| 14 | ||
| 15 | # cat /sys/devices/system/node/node0/cpumap | |
| 16 | f | |
| 17 | ||
| 18 | That difference confuses libvirt, that fails to get the CPU info. Maybe other | |
| 19 | applications are affected by that too. | |
| 20 | ||
| 21 | The proposed change gets the desired behavior and decreases the size of the | |
| 22 | cpumask considerably for smaller systems. | |
| 23 | ||
| 24 | Signed-off-by: Luis Claudio R. Goncalves <[email protected]> | |
| 25 | Signed-off-by: Clark Williams <[email protected]> | |
| 26 | ||
| 27 | diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h | |
| 28 | index d08e4d2a..c7c2ec7 100644 | |
| 29 | --- a/include/linux/cpumask.h | |
| 30 | +++ b/include/linux/cpumask.h | |
| 31 | @@ -28,7 +28,7 @@ typedef struct cpumask { DECLARE_BITMAP(bits, NR_CPUS); } cpumask_t;
| |
| 32 | extern int nr_cpu_ids; | |
| 33 | #endif | |
| 34 | ||
| 35 | -#ifdef CONFIG_CPUMASK_OFFSTACK | |
| 36 | +#if defined(CONFIG_CPUMASK_OFFSTACK) || defined(CONFIG_PREEMPT_RT_BASE) | |
| 37 | /* Assuming NR_CPUS is huge, a runtime limit is more efficient. Also, | |
| 38 | * not all bits may be allocated. */ | |
| 39 | #define nr_cpumask_bits nr_cpu_ids |
