Hi, This fourth version of HST applies the suggestion from Mikulas Patocka to do the ktime_get_ns inside the mpath map_bio instead of generic device-mapper code. This means that struct dm_mpath_io gained another 64bit field. For the request-based case, we continue to use the block layer start time information. With this modification, I was able obtain similar performance on BIO to request-based multipath with HST on the benchmarks shared in v1. v3: https://www.redhat.com/archives/dm-devel/2020-April/msg00308.html v2: https://www.redhat.com/archives/dm-devel/2020-April/msg00270.html v1: https://www.redhat.com/archives/dm-devel/2020-April/msg00176.html Gabriel Krisman Bertazi (1): md: mpath: Pass IO start time to path selector Khazhismel Kumykov (1): md: mpath: Add Historical Service Time Path Selector drivers/md/Kconfig | 11 + drivers/md/Makefile | 1 + drivers/md/dm-historical-service-time.c | 561 ++++++++++++++++++++++++ drivers/md/dm-mpath.c | 12 +- drivers/md/dm-path-selector.h | 2 +- drivers/md/dm-queue-length.c | 2 +- drivers/md/dm-service-time.c | 2 +- 7 files changed, 585 insertions(+), 6 deletions(-) create mode 100644 drivers/md/dm-historical-service-time.c -- 2.26.2 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
