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.
Signed-off-by: Frederic Weisbecker <frede...@kernel.org>
Cc: Chris Metcalf <cmetc...@mellanox.com>
Cc: Rik van Riel <r...@redhat.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Mike Galbraith <efa...@gmx.de>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Christoph Lameter <c...@linux.com>
Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Cc: Wanpeng Li <kernel...@gmail.com>
Cc: Luiz Capitulino <lcapitul...@redhat.com>
---
Documentation/admin-guide/kernel-parameters.txt | 40 ++++++++++++++++---------
1 file changed, 26 insertions(+), 14 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt
b/Documentation/admin-guide/kernel-parameters.txt
index 6b99c8b..62bc8b5 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1727,20 +1727,32 @@
isapnp= [ISAPNP]
Format: <RDP>,<reset>,<pci_scan>,<verbosity>
- isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
- The argument is a cpu list, as described above.
-
- This option can be used to specify one or more CPUs
- to isolate from the general SMP balancing and scheduling
- algorithms. You can move a process onto or off an
- "isolated" CPU via the CPU affinity syscalls or cpuset.
- <cpu number> begins at 0 and the maximum value is
- "number of CPUs in system - 1".
-
- This option is the preferred way to isolate CPUs. The
- alternative -- manually setting the CPU mask of all
- tasks in the system -- can cause problems and
- suboptimal load balancer performance.
+ isolcpus= [KNL,SMP] Isolate a given set of CPUs from disturbance.
+ Format: [flag-list,]<cpu-list>
+
+ Specify one or more CPUs to isolate from disturbances
+ specified in the flag list (default: domain):
+
+ nohz
+ Disable the tick when a single task runs.
+ domain
+ Isolate from the general SMP balancing and scheduling
+ algorithms. Note that performing domain isolation
this way
+ is irreversible. It's not possible to bring back a
CPU to
+ the domains once isolated through isolcpus. It's
strongly
+ advised to use Cpusets instead to disable scheduler
load
+ balancing through the file
"cpuset.sched_load_balance".
+ It offers a much more flexible interface where CPUs
can
+ move in and out of an isolated set anytime.
+
+ You can move a process onto or off an "isolated" CPU
via
+ the CPU affinity syscalls or cpuset.
+ <cpu number> begins at 0 and the maximum value is
+ "number of CPUs in system - 1".
+
+ The format of <cpu-list> is described above.
+
+
iucv= [HW,NET]
--
2.7.4
