1What:           /sys/module/xen_blkback/parameters/max_buffer_pages
2Date:           March 2013
3KernelVersion:  3.11
4Contact:        Roger Pau Monné <roger.pau@citrix.com>
5Description:
6                Maximum number of free pages to keep in each block
7                backend buffer.
8
9What:           /sys/module/xen_blkback/parameters/max_persistent_grants
10Date:           March 2013
11KernelVersion:  3.11
12Contact:        Roger Pau Monné <roger.pau@citrix.com>
13Description:
14                Maximum number of grants to map persistently in
15                blkback. If the frontend tries to use more than
16                max_persistent_grants, the LRU kicks in and starts
17                removing 5% of max_persistent_grants every 100ms.
18
19What:           /sys/module/xen_blkback/parameters/persistent_grant_unused_seconds
20Date:           August 2018
21KernelVersion:  4.19
22Contact:        Roger Pau Monné <roger.pau@citrix.com>
23Description:
24                How long a persistent grant is allowed to remain
25                allocated without being in use. The time is in
26                seconds, 0 means indefinitely long.
27                The default is 60 seconds.
28
29What:           /sys/module/xen_blkback/parameters/buffer_squeeze_duration_ms
30Date:           December 2019
31KernelVersion:  5.6
32Contact:        SeongJae Park <sj@kernel.org>
33Description:
34                When memory pressure is reported to blkback this option
35                controls the duration in milliseconds that blkback will not
36                cache any page not backed by a grant mapping.
37                The default is 10ms.
38
39What:           /sys/module/xen_blkback/parameters/feature_persistent
40Date:           September 2020
41KernelVersion:  5.10
42Contact:        SeongJae Park <sj@kernel.org>
43Description:
44                Whether to enable the persistent grants feature or not.  Note
45                that this option only takes effect on newly created backends.
46                The default is Y (enable).
47