Documentation/ABI/rnbd-clt: Add description for nr_poll_queues

describe how to set nr_poll_queues and enable the polling

Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
Acked-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Link: https://lore.kernel.org/r/20210419073722.15351-15-gi-oh.kim@ionos.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/Documentation/ABI/testing/sysfs-block-rnbd b/Documentation/ABI/testing/sysfs-block-rnbd
index ec716e1..80b420b 100644 (file)
--- a/Documentation/ABI/testing/sysfs-block-rnbd
+++ b/Documentation/ABI/testing/sysfs-block-rnbd
@@ -56,3 +56,9 @@ Date:         Feb 2020
 KernelVersion: 5.7
 Contact:       Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
 Description:   Remap the disconnected device if the session is not destroyed yet.
+
+What:          /sys/block/rnbd<N>/rnbd/nr_poll_queues
+Date:          Feb 2020
+KernelVersion: 5.7
+Contact:       Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:   Contains the number of poll-mode queues

diff --git a/Documentation/ABI/testing/sysfs-class-rnbd-client b/Documentation/ABI/testing/sysfs-class-rnbd-client
index 2aa05b3..0b5997a 100644 (file)
--- a/Documentation/ABI/testing/sysfs-class-rnbd-client
+++ b/Documentation/ABI/testing/sysfs-class-rnbd-client
@@ -85,6 +85,19 @@ Description: Expected format is the following::
 
                By default "rw" is used.
 
+               nr_poll_queues
+                 specifies the number of poll-mode queues. If the IO has HIPRI flag,
+                 the block-layer will send the IO via the poll-mode queue.
+                 For fast network and device the polling is faster than interrupt-base
+                 IO handling because it saves time for context switching, switching to
+                 another process, handling the interrupt and switching back to the
+                 issuing process.
+
+                 Set -1 if you want to set it as the number of CPUs
+                 By default rnbd client creates only irq-mode queues.
+
+                 NOTICE: MUST make a unique session for a device using the poll-mode queues.
+
                Exit Codes:
 
                If the device is already mapped it will fail with EEXIST. If the input