reduce lock congestion and improve SMP scalability of the SCSI/ATA stack,
preparing the ground for the coming next GEOM direct dispatch support.
Replace big per-SIM locks with bunch of smaller ones:
- per-LUN locks to protect device and peripheral drivers state;
- per-target locks to protect list of LUNs on target;
- per-bus locks to protect reference counting;
- per-send queue locks to protect queue of CCBs to be sent;
- per-done queue locks to protect queue of completed CCBs;
- remaining per-SIM locks now protect only HBA driver internals.
While holding LUN lock it is allowed (while not recommended for performance
reasons) to take SIM lock. The opposite acquisition order is forbidden.
All the other locks are leaf locks, that can be taken anywhere, but should
not be cascaded. Many functions, such as: xpt_action(), xpt_done(),
xpt_async(), xpt_create_path(), etc. are no longer require (but allow) SIM
lock to be held.
To keep compatibility and solve cases where SIM lock can't be dropped, all
xpt_async() calls in addition to xpt_done() calls are queued to completion
threads for async processing in clean environment without SIM lock held.
Instead of single CAM SWI thread, used for commands completion processing
before, use multiple (depending on number of CPUs) threads. Load balanced
between them using "hash" of the device B:T:L address.
HBA drivers that can drop SIM lock during completion processing and have
sufficient number of completion threads to efficiently scale to multiple
CPUs can use new function xpt_done_direct() to avoid extra context switch.
Make ahci(4) driver to use this mechanism depending on hardware setup.
Sponsored by: iXsystems, Inc.
MFC after: 2 months
to allow drivers to handle request completion directly without passing
them to the CAM SWI thread removing extra context switch.
Modify all ATA/SATA drivers to use them.
Reviewed by: gibbs, ken
MFC after: 2 weeks
It blocks CAM SWI usage on requests completion, unneeded because of polling
and denied during kernel dumping because of blocked scheduler.
Before r198899 there was periph flag CAM_PERIPH_POLLED, but that was wrong,
because there is whole SIM is polled or handled by SWI, not a single periph.
Tested by: kib
MFC after: 1 month
does - in DragonFly, it's cam_sim_release() what actually frees the
SIM; cam_sim_free does nothing more than calling cam_sim_release().
Here, we drain in cam_sim_free, waiting for refcount to drop to zero.
We cannot do the same think DragonFly does, because after cam_sim_free
returns, client would destroy the sim->mtx, and CAM would trip over
an initialized mutex.
Reviewed by: scottl
Approved by: rwatson (mentor)
Sponsored by: FreeBSD Foundation
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.
is an application space macro and the applications are supposed to be free
to use it as they please (but cannot). This is consistant with the other
BSD's who made this change quite some time ago. More commits to come.
NOTE: These changes will require recompilation of any userland
applications, like cdrecord, xmcd, etc., that use the CAM passthrough
interface. A make world is recommended.
camcontrol.[c8]:
- We now support two new commands, "tags" and "negotiate".
- The tags commands allows users to view the number of tagged
openings for a device as well as a number of other related
parameters, and it allows users to set tagged openings for
a device.
- The negotiate command allows users to enable and disable
disconnection and tagged queueing, set sync rates, offsets
and bus width. Note that not all of those features are
available for all controllers. Only the adv, ahc, and ncr
drivers fully support all of the features at this point.
Some cards do not allow the setting of sync rates, offsets and
the like, and some of the drivers don't have any facilities to
do so. Some drivers, like the adw driver, only support enabling
or disabling sync negotiation, but do not support setting sync
rates.
- new description in the camcontrol man page of how to format a disk
- cleanup of the camcontrol inquiry command
- add support in the 'devlist' command for skipping unconfigured devices if
-v was not specified on the command line.
- make use of the new base_transfer_speed in the path inquiry CCB.
- fix CCB bzero cases
cam_xpt.c, cam_sim.[ch], cam_ccb.h:
- new flags on many CCB function codes to designate whether they're
non-immediate, use a user-supplied CCB, and can only be passed from
userland programs via the xpt device. Use these flags in the transport
layer and pass driver to categorize CCBs.
- new flag in the transport layer device matching code for device nodes
that indicates whether a device is unconfigured
- bump the CAM version from 0x10 to 0x11
- Change the CAM ioctls to use the version as their group code, so we can
force users to recompile code even when the CCB size doesn't change.
- add + fill in a new value in the path inquiry CCB, base_transfer_speed.
Remove a corresponding field from the cam_sim structure, and add code to
every SIM to set this field to the proper value.
- Fix the set transfer settings code in the transport layer.
scsi_cd.c:
- make some variables volatile instead of just casting them in various
places
- fix a race condition in the changer code
- attach unless we get a "logical unit not supported" error. This should
fix all of the cases where people have devices that return weird errors
when they don't have media in the drive.
scsi_da.c:
- attach unless we get a "logical unit not supported" error
scsi_pass.c:
- for immediate CCBs, just malloc a CCB to send the user request in. This
gets rid of the 'held' count problem in camcontrol tags.
scsi_pass.h:
- change the CAM ioctls to use the CAM version as their group code.
adv driver:
- Allow changing the sync rate and offset separately.
adw driver
- Allow changing the sync rate and offset separately.
aha driver:
- Don't return CAM_REQ_CMP for SET_TRAN_SETTINGS CCBs.
ahc driver:
- Allow setting offset and sync rate separately
bt driver:
- Don't return CAM_REQ_CMP for SET_TRAN_SETTINGS CCBs.
NCR driver:
- Fix the ultra/ultra 2 negotiation bug
- allow setting both the sync rate and offset separately
Other HBA drivers:
- Put code in to set the base_transfer_speed field for
XPT_GET_TRAN_SETTINGS CCBs.
Reviewed by: gibbs, mjacob (isp), imp (aha)
