use to synchornize and protect all data objects that are used for that
SIM. Drivers that are not yet MPSAFE register Giant and operate as
usual. RIght now, no drivers are MPSAFE, though a few will be changed
in the coming week as this work settles down.
The driver API has changed, so all CAM drivers will need to be recompiled.
The userland API has not changed, so tools like camcontrol do not need to
be recompiled.
Linux SCSI SG passthrough device API. The intention is to allow for both
running of Linux apps that want to talk to /dev/sg* nodes, and to facilitate
porting of apps from Linux to FreeBSD. As such, both native and linuxolator
entry points and definitions are provided.
Caveats:
- This does not support the procfs and sysfs nodes that the Linux SG
driver provides. Some Linux apps may rely on these for operation,
others may only use them for informational purposes.
- More ioctls need to be implemented.
- Linux uses a naming scheme of "sg[a-z]" for devices, while FreeBSD uses a
scheme of "sg[0-9]". Devfs aliasis (symlinks) are automatically created
to link the two together. However, tools like camcontrol only see the
native names.
- Some operations were originally designed to return byte counts or other
data directly as the syscall return value. The linuxolator doesn't appear
to support this well, so this driver just punts for these cases.
Now that the driver is in place, others are welcome to add missing
functionality. Thanks to Roman Divacky for pushing this work along.
rescan requests. The purpose of this is to allow a SIM
(or other entities) to request a bus rescan and have it
then fielded in a different (process) context from the
caller.
There are probably better ways to accomplish this, but
it's a very small change that helps solve a number of
problems.
Reviewed by: Justin, Ken and Scott.
MFC after: 2 weeks
flash card reader.
Also remove an 'Opened da0 -> <random number>' which is not needed on a daily
basis (available through bootverbose).
Reviewed by: phk, ken
MFC after: 1 week
author can't remember why it was there.
The CTS_SCSI_FLAGS_TAG_ENB remains in place, and makes sense, and is
checked all over the place.
The CTS_SPI_FLAGS_TAG_ENB was probably an attempt to distinguish
protocol and transport tag capabilities. At the very least this can
be confusing and prone to many bugs, so let's just assume that the
transport tag case just flows from the protocol (and vice versa)
for now.
the ORDERED tag. This recoups significant performance gains for many
arrays.
The default is still to send out the ORDERED tag periodically.
Reviewed by: scsi (justin+timeout)
the CAM_NEW_TRAN_CODE that has been in the tree for some years now.
This first step consists solely of adding to or correcting
CAM_NEW_TRAN_CODE pieces in the kernel source tree such
that a both a GENERIC (at least on i386) and a LINT build
with CAM_NEW_TRAN_CODE as an option will compile correctly
and run (at least with some the h/w I have).
After a short settle time, the other pieces (making
CAM_NEW_TRAN_CODE the default and updating libcam
and camcontrol) will be brought in.
This will be an incompatible change in that the size of structures
related to XPT_PATH_INQ and XPT_{GET,SET}_TRAN_SETTINGS change
in both size and content. However, basic system operation and
basic system utilities work well enough with this change.
Reviewed by: freebsd-scsi and specific stakeholders
and CAM_RESRC_UNAVAIL returns. Delay a tunable amount for
either between retries.
This came up because the MPT IOC was returning "IOC out of
resources" for some user and this caused a CAM_RESRC_UNAVAIL
return. Putting a bit of delay between retries helped them
out.
There was some discussion that an async event should be used
to clear CAM_RESRC_UNAVAIL. That's probably a better notion
eventually.
Reviewed by: scsi@freebsd.org (ade, scott)
MFC after: 1 week
REPORT LUNS command to a device.
camcontrol.[c8]: Implement reportluns. This tries to print the LUNs
out in a reasonable format. Only the periph
addressing method has been tested, since very little
hardware that I know of supports the other methods.
scsi_all.[ch]: Revamp the report luns CDB structure and helper
functions. This constitutes a little bit of an API
change, but since the old CDB length was 10 bytes,
and the REPORT LUNS CDB length is actually 12 bytes,
it's clear that no one was using this API in the
first place.
MFC After: 1 week
what to do with it.
This forces us to scan targets sequentially, not in parallel.
The reason we might want to do this is that SPI negotiation
might not work right at the SIM level if we try to do it
in parallel. We *could* fix this for each SIM where this is
broken, but it's a lot harder to do that when we can simply
ask CAM to probe sequentially.
If PIM_SEQSCAN is not set (default), the original behaviour for
probing is unchanged.
LUN probing is still done in parallel for each target in either
case.
While we're at it, clean up some resource leakage for error
cases.
Reviewed by: ken, scott, scsi@
MFC after: 1 week
usage as of SPC2r20. Specifically, handle the BQueue
flag which will indicate that a device supports the
Basic Queueing model (no Head of Queue or Ordered tags).
When this flag is set, SID_CmdQueue is clear. This has
causes FreeBSD to assume that the device did not support
tagged operations.
MFC after: 1 month
This version of scsi_target.c removes all SMP locking until
we have a lock-aware CAM stack. This allows us to use KNOTE
without a panic at least.
It's not yet clear whether target mode is working yet or not.
Discussed with: Scott, Ken, Nate, Justin
return to user space w/o waiting for I/O to complete.
I tried to get several folks who know this code better than me to review it
with no luck. I *do* know that w/o this code, using the SCSI target driver
panics in userret (if it doesn't panic in knote first).
an application to upon a tape (yea, even the non-control device) even if
it cannot establish a mount session. If the open cannot establish a mount
session and O_NONBLOCK was specified, the tape becomes 'open pending mount'.
All I/O operations that would require access to a tape thereafter until
a close attempt to initiate the mount session. If the mount session succeeds,
the tape driver transitions to full open state, else returns an appropriate
I/O error (ENXIO).
At the same time, add a change that remembers whether tape is being opened
read-only. If so, disallow 'write' operations like writing filemarks that
bypass the normal read-only filtering operations that happen in the write(2)
syscall.
Reviewed by: ken, justin, grog
MFC after: 2 weeks
Suggested by: The Bacula Team
operations before returning. Point the bus at a dummy cam_sim
structure so that any CCBs will complete immediately with a
CAM_DEV_NOT_THERE status, and ensure that any xpt_schedule() calls
on the bus's devices will immediately call the peripheral's
periph_start() routine. Also repeat the async messages because
devices that were part of the way through being probed may appear
after the original AC_LOST_DEVICE was sent, and would otherwise
never go away.
These changes make it possible to deregister a bus and free the SIM
at most stages during bus probing without the usual crashes in
camisr(). In particular, plugging in a umass device and then
unplugging it as soon as the first probe messages appeared would
almost always result in a crash. Now the device just goes away with
a few CAM errors and all references to the CAM bus, target and
device are dropped correctly.
CAM_LUN_INVALID or CAM_TID_INVALID. Retries were being triggered
here when a umass device was unplugged, and while the retries
themselves are probably harmless, they complicated finding the real
SIM removal problems.
the underlying drive had been hot-unplugged from the system. Here
is a specific example. Filesystem code had opened /dev/da1s1e.
Subsequently, the drive was hot-unplugged. This (correctly) caused
all of the associated /dev/da1* entries to be deleted. When the
filesystem later realized that the drive was gone it closed the
device, reducing the write-access counts to 0 on the geom providers
for da1s1e, da1s1, and da1. This caused geom to re-taste the
providers, resulting in the devices being created again. When the
drive was hot-plugged back in, it resulted in duplicate /dev entries
for da1s1e, da1s1, and da1.
This fix adds a new disk_gone() function which is called by CAM when a
drive goes away. It orphans all of the providers associated with the
drive, setting an error condition of ENXIO in each one. In addition,
we prevent a re-taste on last close for writing if an error condition
has been set in the provider.
Sponsored by: Isilon Systems
Reviewed by: phk
MFC after: 1 week
tunable (until we get REPORT LUNS in place).
If we're probing luns, and each probe succeeds, we keep going past
lun 7 if we're a SCSI3 or better device (until we fail to probe).
If we're probing luns, and a probe fails, we only keep going if
we're quirked *for* it (CAM_QUIRK_HILUNS), and if we're not quirked
*against* it (CAM_QUIRK_NOHILUNS), or we're a SCSI3 or better device
and the tunable (kern.cam.cam_srch_hi) is set non-zero.
Reviewed by: nate@rootlabs.org, gibbs@scsiguy.com, ken@kdm.com, scottl@samsco.org
MFC after: 1 week
event handler, dev_clone, which accepts a credential argument.
Implementors of the event can ignore it if they're not interested,
and most do. This avoids having multiple event handler types and
fall-back/precedence logic in devfs.
This changes the kernel API for /dev cloning, and may affect third
party packages containg cloning kernel modules.
Requested by: phk
MFC after: 3 days
- Introducing the possibility of using locks different than mutexes
for the knlist locking. In order to do this, we add three arguments to
knlist_init() to specify the functions to use to lock, unlock and
check if the lock is owned. If these arguments are NULL, we assume
mtx_lock, mtx_unlock and mtx_owned, respectively.
- Using the vnode lock for the knlist locking, when doing kqueue operations
on a vnode. This way, we don't have to lock the vnode while holding a
mutex, in filt_vfsread.
Reviewed by: jmg
Approved by: re (scottl), scottl (mentor override)
Pointyhat to: ssouhlal
Will be happy: everyone
module-specific malloc types. These should help us to pinpoint the
possible memory leakage in the future.
- Implementing xpt_alloc_ccb_nowait() and replacing all malloc/free based
CCB memory management with xpt_alloc_ccb[_nowait]/xpt_free_ccb. Hopefully
this would be helpful if someday we move the CCB allocator to use UMA
instead of malloc().
Encouraged by: jeffr, rwatson
Reviewed by: gibbs, scottl
Approved by: re (scottl)
(depends on how many memory you have) observed through "tar -tvf /dev/sa0."
Without this patch, RELENG_5 and HEAD panics with something like:
kmem_malloc(4096): kmem_map too small: 42258432 total allocated
RELENG_4 doesn't panic but spews following errors:
camq_init: - cannot malloc array!
Reviewed by: gibbs, scottl
Approved by: re (scottl)
MFC after: 3 days
period value. I suppose the BT adapter driver should be
fixed, but more importantly we should protect against
dividing by zero.
PR: kern/75603
MFC after: 1 week
succeed if there was no media in the drive.
This was broken in rev 1.72 when the media check was added to cdioctl().
For now, check the ioctl group to decide whether to check for media or not.
(We only need to check for media on CD-specific ioctls.)
Reported by: bland
MFC after: 3 days
disables tag queuing temporarily in order to allow controllers a window
to safely perform transfer negotiation with non-compliant devices. Before
this change, CAM would restore the queue depth to the controller specified
maximum or device quirk level rather than any depth determined by reactions
to QUEUE FULL/BUSY events or an explicit user setting.
During device probe, initialize the flags field for XPT_SCAN_BUS.
The uninitialized value often confused CAM into not bothering to
issue an AC_FOUND_DEVICE async event for new devices. The reason
this bug wasn't reported earlier is that CAM manually announces
devices after the initial system bus scans.
MFC: 3 days
Giant held. In camisr(), move the ccb_bioq elements to a temporary local list
and then process the elements off of that list. This enables the list to be
processed by only taking the ccb_bioq_lock once and only for a very short
time.
ccb_bioq_lock is a leaf mutex, so it's fine to call xpt_done() with other
locks held. This is just a very minor step in the work to lock CAM, but
it allows us to avoid some messy locking/unlock dances in certain drivers.
providing special version of CDIOCREADSUBCHANNEL ioctl(), which assumes that
result has to be placed into kernel space not user space. In the long run
more generic solution has to be designed WRT emulating various ioctl()s
that operate on userspace buffers, but right now there is only one such
ioctl() is emulated, so that it makes little sense.
MFC after: 2 weeks
It reports itself as SCSI-3 but doesnt like getting probed on high luns
because it hangs hard after finding itself again on lun 32...
Suggested by: Kenneth Merry
its ability to automatically scan and attach luns for modern storage
which has luns in the 0..1000 range, not 0..7.
The correct thing would be to do REPORT LUNS for devices whose LUN0
version shows a version >= SCSI3, but lacking that we should be able
to search higher than LUN 7 if we're >= SCSI3 with no ill effects.
This change keeps all of the QUIRK_HILUNS quirks, obeys the QUIRK_NOLUNS,
and introduces a QUIRK_NOHILUNS which will keep searches above LUN 7
happening for devices that report >= SCSI3 compliance. I doubt the latter
will be needed, but you never know.
This allowed me to randomly scan and attach > 500 disks at a time in
a situation where quirking for QUIRK_HILUNS wasn't practical (the
vendor id and product id changes of the virtualization changes
constantly).
Reviewed by: ken@freebsd.org, scottl@freebsd.org, gibbs@freebsd.org
MFC after: 2 weeks
to request from devices during the "long inquiry" portion of our probe.
This same bug was fixed in the 4.x stream a few years ago, but the fix
was never propogated to -current.
This fix is slightly different than in -stable:
o Use offsetof() instead of a hard coded constant so as the make
the code more self-explainatory.
o Round odd long inquiry lengths up so as to avoid tickling ignore
wide residue bugs in broken parallel SCSI devices running with a
wide transfer negotiation.
MFC: 3 days
sectorsize in order to avoid a lot of checks around various divisions etc.
Enforce the sectorsize being > 0 with a KASSERT on successful open.
Fix scsi_cd.c to return 2k sectors when no media inserted.
a more complete subsystem, and removes the knowlege of how things are
implemented from the drivers. Include locking around filter ops, so a
module like aio will know when not to be unloaded if there are outstanding
knotes using it's filter ops.
Currently, it uses the MTX_DUPOK even though it is not always safe to
aquire duplicate locks. Witness currently doesn't support the ability
to discover if a dup lock is ok (in some cases).
Reviewed by: green, rwatson (both earlier versions)
for unknown events.
A number of modules return EINVAL in this instance, and I have left
those alone for now and instead taught MOD_QUIESCE to accept this
as "didn't do anything".
The big lines are:
NODEV -> NULL
NOUDEV -> NODEV
udev_t -> dev_t
udev2dev() -> findcdev()
Various minor adjustments including handling of userland access to kernel
space struct cdev etc.
patterns. (These lines are correct the other two times they appear.)
Reported by: "Ted Unangst" <tedu@coverity.com>
Approved by: rwatson (mentor), ken (scsi)
Introduce d_version field in struct cdevsw, this must always be
initialized to D_VERSION.
Flip sense of D_NOGIANT flag to D_NEEDGIANT, this involves removing
four D_NOGIANT flags and adding 145 D_NEEDGIANT flags.
Free approx 86 major numbers with a mostly automatically generated patch.
A number of strategic drivers have been left behind by caution, and a few
because they still (ab)use their major number.
Previously the "struct disk" were owned by the device driver and this
gave us problems when the device disappared and the users of that device
were not immediately disappearing.
Now the struct disk is allocate with a new call, disk_alloc() and owned
by geom_disk and just abandonned by the device driver when disk_create()
is called.
Unfortunately, this results in a ton of "s/\./->/" changes to device
drivers.
Since I'm doing the sweep anyway, a couple of other API improvements
have been carried out at the same time:
The Giant awareness flag has been flipped from DISKFLAG_NOGIANT to
DISKFLAG_NEEDSGIANT
A version number have been added to disk_create() so that we can detect,
report and ignore binary drivers with old ABI in the future.
Manual page update to follow shortly.
thread being waken up. The thread waken up can run at a priority as
high as after tsleep().
- Replace selwakeup()s with selwakeuppri()s and pass appropriate
priorities.
- Add cv_broadcastpri() which raises the priority of the broadcast
threads. Used by selwakeuppri() if collision occurs.
Not objected in: -arch, -current
instead of retrying them blindly.
This should fix some of the problems people have been having with cdrom
drives taking a long time to probe. This should also eliminate the need
for the initial TUR in cdsize().
cam_periph.c: Don't keep retrying if the error we get back is a fatal
error. This should help us detect the transition from
"Logical unit not ready, cause not reportable" to "Medium
not present" in the "TUR many" handler. (The TUR many
handler gets triggered for Logical unit not ready, cause
not reportable errors.)
scsi_cd.c: Remove the initial test unit ready in cdsize(). Hopefully
it isn't necessary after the above change.
Submitted by: gibbs (mostly)
Tested by: peter
MFC After: 2 weeks
an uninitialized sysctl_ctx, using flag DA_FLAG_SCTX_INIT. This
prevents a panic encoutered with some umass units that probe correctly
but fail to attach. Same problem, and same fix, as scsi_cd.c rev. 1.86.
Reviewed by: njl, ken
has been initialized.
(cdsysctlinit): Set flag CD_FLAG_SCTX_INIT after sysctl_ctx has been
initialized.
This resolves a panic encountered when a cd drive is sucessfully probed
but fails to attach.
Reviewed by: ken
completion of recovery is indicated by positioning the CAM_AUTOSNS_VALID
bit in the status field of the CCB, not in the flags field.
This fixes an endless loop of sense recovery actions.
Reviewed by: ken
This commit puts the relevant code snippets under #ifdef GONE_IN_5
(rather than #ifndef BURN_BRIDGES) thereby disabling the code now.
The code wil be entirely removed before 5.2 unless we find reasons
why this would be a bad idea.
Approach suggested by: imp
For the floppy driver, use fdcontrol to manipulate density selection.
For the CD drivers, the 'a' and 'c' suffix is without actual effect and
any applications insisting on it can be satisfied with a symlink:
ln -s /dev/cd0 /dev/cd0a
Ongoing discussion may result in these pieces of code being removed before
the 5-stable branch as opposed to after.
into targreadfilt(). Unlock around calls to notify_user(). If an application
is sending CCBs while the endpoint is shutting down, this may result in
incomplete disable. A more complete solution will come with a "dying" flag.
Submitted by: simokawa
out of cdregister() and daregister(), which are run from interrupt context.
The sysctl code does blocking mallocs (M_WAITOK), which causes problems
if malloc(9) actually needs to sleep.
The eventual fix for this issue will involve moving the CAM probe process
inside a kernel thread. For now, though, I have fixed the issue by moving
dynamic sysctl variable creation for these two drivers to a task queue
running in a kernel thread.
The existing task queues (taskqueue_swi and taskqueue_swi_giant) run in
software interrupt handlers, which wouldn't fix the problem at hand. So I
have created a new task queue, taskqueue_thread, that runs inside a kernel
thread. (It also runs outside of Giant -- clients must explicitly acquire
and release Giant in their taskqueue functions.)
scsi_cd.c: Remove sysctl variable creation code from cdregister(), and
move it to a new function, cdsysctlinit(). Queue
cdsysctlinit() to the taskqueue_thread taskqueue once we
have fully registered the cd(4) driver instance.
scsi_da.c: Remove sysctl variable creation code from daregister(), and
move it to move it to a new function, dasysctlinit().
Queue dasysctlinit() to the taskqueue_thread taskqueue once
we have fully registered the da(4) instance.
taskqueue.h: Declare the new taskqueue_thread taskqueue, update some
comments.
subr_taskqueue.c:
Create the new kernel thread taskqueue. This taskqueue
runs outside of Giant, so any functions queued to it would
need to explicitly acquire/release Giant if they need it.
cd.4: Update the cd(4) man page to talk about the minimum command
size sysctl/loader tunable. Also note that the changer
variables are available as loader tunables as well.
da.4: Update the da(4) man page to cover the retry_count,
default_timeout and minimum_cmd_size sysctl variables/loader
tunables. Remove references to /dev/r???, they aren't used
any longer.
cd.9: Update the cd(9) man page to describe the CD_Q_10_BYTE_ONLY
quirk.
taskqueue.9: Update the taskqueue(9) man page to describe the new thread
task queue, and the taskqueue_swi_giant queue.
MFC after: 3 days
commands. Add a quirk for the Creative Nomad MuVo USB device that uses
it as well as NO_SYNCHRONIZE_CACHE.
PR: kern/53094
Submitted by: Richard Nyberg <rnyberg@it.su.se>
MFC after: 3 days
to such devices. If a device fails due to this commit, add:
options DA_OLD_QUIRKS
to the kernel config and recompile. Then send the output of "camcontrol
inquiry da0" to scsi@freebsd.org so the quirk can be re-enabled.
receive 6 byte commands. Add a check for this flag to da(4) and cd(4) so
that they honor it. This is a quick workaround for many devices (especially
USB) that require da(4) quirks to operate. The more complete approach is
to finish the new transport code which will be aware of the SCSI version a
transport implements.
MFC after: 1 day
Devices below may experience a change in geometry.
* Due to a bug, aic(4) never used extended geometry. Changes all drives
>1G to now use extended translation.
* sbp(4) drives exactly 1 GB in size now no longer use extended geometry.
* umass(4) drives exactly 1 GB in size now no longer use extended geometry.
For all other controllers in this commit, this should be a no-op.
Looked over by: scottl
Devices below may experience a change in geometry.
* Due to a bug, aic(4) never used extended geometry. Changes all drives
>1G to now use extended translation.
* sbp(4) drives exactly 1 GB in size now no longer use extended geometry.
* umass(4) drives exactly 1 GB in size now no longer use extended geometry.
For all other controllers in this commit, this should be a no-op.
PR:
Submitted by:
Looked over by: scottl
Approved by:
Obtained from:
MFC after:
Clarify that the implicit fallthrough was *not* intentional (thanks, Poul!)
and reorganize the code so a correct fallthrough (with /* FALLTHROUGH */)
occurs.
- Make sure we don't release the READ CAPACITY CCB twice
- If we have a device that needs a 16 byte READ CAPACITY command, make
sure we call xpt_schedule() so we can get a CCB.
- Don't unlock the peripheral until we're fully probed.
Many thanks to Julian Elischer for providing hardware and testing this.
Tested by: julian
to 0 initially. It seems that the ia64 backend isn't as "smart" as the
i386 backend, which realized that those variables were only set or used
when error == 0, and thus were not used uninitialized.
using 512 byte blocks).
cam_ccb.h: Bump up volume_size and cylinders in ccb_calc_geometry to
64 bits and 32 bits respectively, so we can hold larger
device sizes. cylinders would overflow at about 500GB.
Bump CAM_VERSION for this change. Note that this will
require a recompile of all applications that talk to the
pass(4) driver.
scsi_all.c: Add descriptions for READ/WRITE(16), update READ/WRITE(12)
descriptions, add descriptions for SERVICE ACTION IN/OUT.
Add a new function, scsi_read_capacity_16(), that issues
the read capacity service action. (Necessary for arrays
larger than 2^32 sectors.) Update scsi_read_write() to use
a 64 bit LBA and issue READ(16) or WRITE(16) if necessary.
NOTE the API change. This should be largely transparnet
to most userland applications at compile time, but will
break binary compatibility. The CAM_VERSION bump, above,
also serves the purpose of forcing a recompile for any
applications that talk to CAM.
scsi_all.h: Add 16 byte READ/WRITE structures, structures for 16 byte
READ CAPACITY/SERVICE ACTION IN. Add scsi_u64to8b() and
scsi_8btou64.
scsi_da.c: The da(4) driver probe now has two stages for devices
larger than 2TB. If a standard READ CAPACITY(10) returns
0xffffffff, we issue the 16 byte version of read capacity
to determine the true array capacity. We also do the same
thing in daopen() -- use the 16 byte read capacity if the
device is large enough.
The sysctl/loader code has also been updated to accept
16 bytes as a minimum command size.
Casio QV-R3 USB camera, which appears to use a Pentax chipset
M-Systems DiskOnKey USB flash key
Feiya "slider" dual-slot flash reader
SmartDisk (Mitsumi) USB floppy drive
PR: kern/46545, kern/47793, kern/50020, kern/50226
Retain the mistake of not updating the devstat API for now.
Spell bioq_disksort() consistently with the remaining bioq_*().
#include <geom/geom_disk.h> where this is more appropriate.
cdcleanup(). This fixes sysctl problems ("can't re-use a leaf") when
someone adds another peripheral at the same unit number. (e.g. rescan da0,
it goes away, then rescan again and da0 comes back, but since we haven't
cleaned up the sysctl variables from the last da0 instance, we can't
register the variables for the new instance under the same name.)
Reported by: njl
Tested by: njl
Kernel:
Change statistics to use the *uptime() timescale (ie: relative to
boottime) rather than the UTC aligned timescale. This makes the
device statistics code oblivious to clock steps.
Change timestamps to bintime format, they are cheaper.
Remove the "busy_count", and replace it with two counter fields:
"start_count" and "end_count", which are updated in the down and
up paths respectively. This removes the locking constraint on
devstat.
Add a timestamp argument to devstat_start_transaction(), this will
normally be a timestamp set by the *_bio() function in bp->bio_t0.
Use this field to calculate duration of I/O operations.
Add two timestamp arguments to devstat_end_transaction(), one is
the current time, a NULL pointer means "take timestamp yourself",
the other is the timestamp of when this transaction started (see
above).
Change calculation of busy_time to operate on "the salami principle":
Only when we are idle, which we can determine by the start+end
counts being identical, do we update the "busy_from" field in the
down path. In the up path we accumulate the timeslice in busy_time
and update busy_from.
Change the byte_* and num_* fields into two arrays: bytes[] and
operations[].
Userland:
Change the misleading "busy_time" name to be called "snap_time" and
make the time long double since that is what most users need anyway,
fill it using clock_gettime(CLOCK_MONOTONIC) to put it on the same
timescale as the kernel fields.
Change devstat_compute_etime() to operate on struct bintime.
Remove the version 2 legacy interface: the change to bintime makes
compatibility far too expensive.
Fix a bug in systat's "vm" page where boot relative busy times would
be bogus.
Bump __FreeBSD_version to 500107
Review & Collaboration by: ken