[PATCH v7 10/10] docs: add io_queue flag to isolcpus
From: Daniel Wagner <wagi@kernel.org>
Date: 2025-07-02 16:34:32
Also in:
linux-nvme, linux-scsi, lkml, virtualization
Subsystem:
documentation, the rest · Maintainers:
Jonathan Corbet, Linus Torvalds
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@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