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authorWarner Losh <imp@FreeBSD.org>2021-04-21 18:10:42 +0000
committerWarner Losh <imp@FreeBSD.org>2021-04-22 17:23:29 +0000
commit9a5a5c1576b4ce308a97e0bce887261701ae3edc (patch)
treec40eb2faeb35f1b0c5b5c018632e86bcfe805d0b
parent89c3c32647a5099b297af2958e5a939eff0c0ce0 (diff)
downloadsrc-9a5a5c1576b4ce308a97e0bce887261701ae3edc.tar.gz
src-9a5a5c1576b4ce308a97e0bce887261701ae3edc.zip
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
-rw-r--r--sys/dev/vmware/pvscsi/pvscsi.c3
1 files changed, 2 insertions, 1 deletions
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 @@ finish_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;