Author: imp Date: Wed Sep 9 22:29:44 2020 New Revision: 365528 URL: https://svnweb.freebsd.org/changeset/base/365528
Log: MFC r361867: r361867 | imp | 2020-06-06 00:21:20 -0600 (Sat, 06 Jun 2020) | 4 lines Document all the sysctl values for the nda devices. Include some minimal documentation on namespace support for nda devices. Fix a few typos and formatting nits to apease igor. Modified: stable/12/share/man/man4/nda.4 Directory Properties: stable/12/ (props changed) Modified: stable/12/share/man/man4/nda.4 ============================================================================== --- stable/12/share/man/man4/nda.4 Wed Sep 9 22:24:09 2020 (r365527) +++ stable/12/share/man/man4/nda.4 Wed Sep 9 22:29:44 2020 (r365528) @@ -25,7 +25,7 @@ .\" .\" $FreeBSD$ .\" -.Dd December 20, 2017 +.Dd June 6, 2020 .Dt NDA 4 .Os .Sh NAME @@ -48,36 +48,156 @@ variables and .Xr loader 8 tunables: .Bl -tag -width 12 +.It Va hw.nvme.use_nvd +The +.Xr nvme 4 +driver will create +.Nm +device nodes for block storage when set to 0. +Create +.Xr nvd 4 +device nodes for block storage when set to 1. +See +.Xr nvd 4 +when set to 1. +.It Va kern.cam.nda.nvd_compat +When set to 1, +.Xr nvd 4 +aliases will be created for all +.Nm +devices, including partitions and other +.Xr goem 4 +providers that take their names from the disk's name. +.Xr nvd +devices will not, however, be reported in the +.Va kern.disks +.Xr sysctl 8 . .It Va kern.cam.nda.sort_io_queue -.Pp This variable determines whether the software queued entries are sorted in LBA order or not. Sorting is almost always a waste of time. The default is to not sort. +.It Va kern.cam.nda.enable_biospeedup +This variable determines if the +.Nm +devices participate in the speedup protocol. +When the device participates in the speedup, then when the upper layers +send a +.Va BIO_SPEEDUP , +all current +.Va BIO_DELETE +requests not yet sent to the hardware are completed successfully immediate +without sending them to the hardware. +Used in low disk space scenarios when the filesystem encounters +a critical shortage and needs blocks immediately. +Since trims have maximum benefit when the LBA is unused for a long time, +skipping the trim when space is needed for immediate writes results in little to +no excess wear. +When participation is disabled, +.Va BIO_SPEEDUP +requests are ignored. +.It Va kern.cam.nda.max_trim +The maximum number of LBA ranges to be collected together for each DSM trims +send to the hardware. +Defaults to 256, which is the maximum number of ranges the protocol supports. +Sometimes poor trim performance can be mitigated by limiting the number of +ranges sent to the device. +This value must be between 1 and 256 inclusive. .El .Pp The following report per-device settings, and are read-only unless -otherwise indicated. Replace +otherwise indicated. +Replace .Va N with the device unit number. .Bl -tag -width 12 .It Va kern.cam.nda.N.rotating -.Pp This variable reports whether the storage volume is spinning or flash. -It's value is hard coded to 0 indicating flash. +Its value is hard coded to 0 indicating flash. .It Va kern.cam.nda.N.unmapped_io This variable reports whether the .Nm driver accepts unmapped I/O for this unit. +.It Va kern.cam.nda.N.flags +This variable reports the current flags. +.Bl -tag -width 12 +.It Va OPEN +The device is open. +.It Va DIRTY +Set when a write to the drive is scheduled. +Cleared after flush commands. +.It Va SCTX_INIT +Internal flag set after +.Xr sysctl 8 +nodes have been created. +.El +.It Va kern.cam.nda.N.sort_io_queue +Same as the +.Va kern.cam.nda.sort_io_queue +tunable. +.It Va kern.cam.nda.N.trim_ticks +Writable. +When greater than zero, hold trims for up to this many ticks before sending +to the drive. +Sometimes waiting a little bit to collect more trims to send at one time +improves trim performance. +When 0, no delaying of trims are done. +.It Va kern.cam.nda.N.trim_goal +Writable. +When delaying a bit to collect multiple trims, send the accumulated DSM TRIM to +the drive. +.It Va kern.cam.nda.N.trim_lbas +Total number of LBAs that have been trimmed. +.It Va kern.cam.nda.N.trim_ranges +Total number of LBA ranges that have been trimmed. +.It Va kern.cam.nda.N.trim_count +Total number of trims sent to the hardware. +.It Va kern.cam.nda.N.deletes +Total number of +.Va BIO_DELETE +requests queued to the device. +.El +.Sh NAMESPACE MAPPING +Each +.Xr nvme 4 +drive has one or more namespaces associated with it. +One instance of the +.Nm +driver will be created for each of the namespaces on +the drive. +All the +.Nm +nodes for a +.Xr nvme 4 +device are at target 0. +However, the namespace ID maps to the CAM lun, as reported +in kernel messages and in the +.Va devlist +sub command of +.Xr camcontrol 8 . +.Pp +Namespaces are managed with the +.Va ns +sub command of +.Xr nvmecontrol 8 . +Not all drives support namespace management, +but all drives support at least one namespace. +Device nodes for +.Nm +will be created and destroyed dynamically as +namespaces are activated or detached. .Sh FILES .Bl -tag -width ".Pa /dev/nda*" -compact .It Pa /dev/nda* NVMe storage device nodes .El .Sh SEE ALSO +.Xr cam 4 , +.Xr geom 4 , +.Xr nvd 4 , .Xr nvme 4 , -.Xr nvd 4 +.Xr gpart 8 .Sh HISTORY The .Nm _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
