[PATCH v7 10/10] docs: add io_queue flag to isolcpus

[Daniel Wagner]

The io_queue flag informs multiqueue device drivers where to place
hardware queues. Document this new flag in the isolcpus
command-line argument description.

Signed-off-by: Daniel Wagner <wagi at kernel.org>
---
 Documentation/admin-guide/kernel-parameters.txt | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index f1f2c0874da9ddfc95058c464fdf5dabaf0de713..7594ac5448575cc895ebf7af0fe051d42dc5e0e9 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2590,7 +2590,6 @@
 			  "number of CPUs in system - 1".
 
 			managed_irq
-
 			  Isolate from being targeted by managed interrupts
 			  which have an interrupt mask containing isolated
 			  CPUs. The affinity of managed interrupts is
@@ -2613,6 +2612,24 @@
 			  housekeeping CPUs has no influence on those
 			  queues.
 
+			io_queue
+			  Isolate from I/O queue work caused by multiqueue
+			  device drivers. Restrict the placement of
+			  queues to housekeeping CPUs only, ensuring that
+			  all I/O work is processed by a housekeeping CPU.
+
+			  Housekeeping CPUs that serve isolated CPUs
+			  cannot be offlined.
+
+			  The io_queue configuration takes precedence over
+			  managed_irq; thus, when io_queue is used,
+			  managed_irq has no effect.
+
+			  Note: When an isolated CPU issues an I/O request,
+			  it is forwarded to a housekeeping CPU. This will
+			  trigger a software interrupt on the completion
+			  path.
+
 			The format of <cpu-list> is described above.
 
 	iucv=		[HW,NET]

-- 
2.50.0