From 9a5a5c1576b4ce308a97e0bce887261701ae3edc Mon Sep 17 00:00:00 2001 From: Warner Losh Date: Wed, 21 Apr 2021 12:10:42 -0600 Subject: [PATCH] pvscsi: Advertise maxio of 256k. While the PV SCSI SG list can handle 512k of SG entries, it can only do so for I/O that's aligned to 4k or better. newfs_msdos does unaligned I/O, so triggers too long for host errors in cam when a 512k I/O is attempted. Prefer power of 2 256k to the absolute maximum 508k, though that can be revisited should the latter show to give significant performance improvement. MFC After: 3 days Tested by: darius on discord (508k version of patch) Sponsored by: Netflix --- sys/dev/vmware/pvscsi/pvscsi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/sys/dev/vmware/pvscsi/pvscsi.c b/sys/dev/vmware/pvscsi/pvscsi.c index 3ca905313897..ad32d2ab4959 100644 --- a/sys/dev/vmware/pvscsi/pvscsi.c +++ b/sys/dev/vmware/pvscsi/pvscsi.c @@ -1423,7 +1423,8 @@ pvscsi_action(struct cam_sim *sim, union ccb *ccb) strlcpy(cpi->sim_vid, "VMware", SIM_IDLEN); strlcpy(cpi->hba_vid, "VMware", HBA_IDLEN); strlcpy(cpi->dev_name, cam_sim_name(sim), DEV_IDLEN); - cpi->maxio = PVSCSI_MAX_SG_ENTRIES_PER_SEGMENT * PAGE_SIZE; + /* Limit I/O to 256k since we can't do 512k unaligned I/O */ + cpi->maxio = (PVSCSI_MAX_SG_ENTRIES_PER_SEGMENT / 2) * PAGE_SIZE; cpi->protocol = PROTO_SCSI; cpi->protocol_version = SCSI_REV_SPC2; cpi->transport = XPORT_SAS;