Document the latest updates on the isolcpus= boot option. While at it, let's also fix the details about the preferred way to isolate a set of CPUs from the scheduler general domains. Cpusets offer a much better interface to achieve that.
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| 1727 | 1727 | isapnp= [ISAPNP] |
| 1728 | 1728 | Format: <RDP>,<reset>,<pci_scan>,<verbosity> |
| 1729 | 1729 | |
| 1730 | − isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. | |
| 1731 | − The argument is a cpu list, as described above. | |
| 1730 | + isolcpus= [KNL,SMP] Isolate a given set of CPUs from disturbance. | |
| 1731 | + [Deprecated - use cpusets instead] | |
| 1732 | + Format: [flag-list,]<cpu-list> | |
| 1733 | + | |
| 1734 | + Specify one or more CPUs to isolate from disturbances | |
| 1735 | + specified in the flag list (default: domain): | |
| 1736 | + | |
| 1737 | + nohz | |
| 1738 | + Disable the tick when a single task runs. | |
| 1739 | + domain | |
| 1740 | + Isolate from the general SMP balancing and scheduling | |
| 1741 | + algorithms. Note that performing domain isolation this way | |
| 1742 | + is irreversible: it's not possible to bring back a CPU to | |
| 1743 | + the domains once isolated through isolcpus. It's strongly | |
| 1744 | + advised to use cpusets instead to disable scheduler load | |
| 1745 | + balancing through the "cpuset.sched_load_balance" file. | |
| 1746 | + It offers a much more flexible interface where CPUs can | |
| 1747 | + move in and out of an isolated set anytime. | |
| 1748 | + | |
| 1749 | + You can move a process onto or off an "isolated" CPU via | |
| 1750 | + the CPU affinity syscalls or cpuset. | |
| 1751 | + <cpu number> begins at 0 and the maximum value is | |
| 1752 | + "number of CPUs in system - 1". | |
| 1753 | + | |
| 1754 | + The format of <cpu-list> is described above. | |
| 1755 | + | |
| 1732 | 1756 | |
| 1733 | − This option can be used to specify one or more CPUs | |
| 1734 | − to isolate from the general SMP balancing and scheduling | |
| 1735 | − algorithms. You can move a process onto or off an | |
| 1736 | − "isolated" CPU via the CPU affinity syscalls or cpuset. | |
| 1737 | − <cpu number> begins at 0 and the maximum value is | |
| 1738 | − "number of CPUs in system - 1". | |
| 1739 | − | |
| 1740 | − This option is the preferred way to isolate CPUs. The | |
| 1741 | − alternative -- manually setting the CPU mask of all | |
| 1742 | − tasks in the system -- can cause problems and | |
| 1743 | − suboptimal load balancer performance. | |
| 1744 | 1757 | |
| 1745 | 1758 | iucv= [HW,NET] |
| 1746 | 1759 | |