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: Maximilian Heyne <mheyne@amazon.de> 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: Maximilian Heyne <mheyne@amazon.de> 43Description: 44 Whether to enable the persistent grants feature or not. Note 45 that this option only takes effect on newly connected backends. 46 The default is Y (enable). 47