Messages in this thread | | | From | Juergen Gross <> | Subject | [PATCH v3 0/5] xen/blk: persistent grant rework | Date | Mon, 13 Aug 2018 16:01:09 +0200 |
| |
Persistent grants are used in the Xen's blkfront/blkback drivers to avoid mapping/unmapping of I/O buffers in the backend for each I/O.
While this speeds up processing quite a bit there are problems related to persistent grants in some configurations: domains with multiple block devices making use of persistent grants might suffer from a lack of grants if each of the block devices experienced a high I/O load at some time. This is due to the number of persistent grants per device only to be limited by a rather high maximum value, but never being released even in case of longer times without any I/O.
This series modifies xen-blkback to unmap any domU page mapped via a persistent grant after a timeout (default: 60 seconds). The timeout is set to its default value again when a persistent grant has been used for an I/O.
xen-blkfront is modified to scan every 10 seconds for persistent grants not in use by blkback any more and to remove such grants.
The last 3 patches are small cleanups of blkfront and blkback drivers.
V3: - patch 1: make timeout parameter static
V2: - patch 1: added new module parameter doc - patch 1: removed PERSISTENT_GNT_WAS_ACTIVE flag - patch 2: removed global worker active flag - added new patch 4
Juergen Gross (5): xen/blkback: don't keep persistent grants too long xen/blkfront: cleanup stale persistent grants xen/blkfront: reorder tests in xlblk_init() xen/blkback: move persistent grants flags to bool xen/blkback: remove unused pers_gnts_lock from struct xen_blkif_ring
Documentation/ABI/testing/sysfs-driver-xen-blkback | 10 ++ drivers/block/xen-blkback/blkback.c | 99 ++++++++++--------- drivers/block/xen-blkback/common.h | 14 +-- drivers/block/xen-blkfront.c | 110 ++++++++++++++++++--- 4 files changed, 163 insertions(+), 70 deletions(-)
-- 2.13.7
| |