- Replace ordered_tag_count counter with single flag;
- From da remove outstanding_cmds counter, duplicating pending_ccbs list;
- From da_softc remove unused links field.
information.
The existing algorithm selects a preferred leaf vdev based on offset of the zio
request modulo the number of members in the mirror. It assumes the devices are
of equal performance and that spreading the requests randomly over both drives
will be sufficient to saturate them. In practice this results in the leaf vdevs
being under utilized.
The new algorithm takes into the following additional factors:
* Load of the vdevs (number outstanding I/O requests)
* The locality of last queued I/O vs the new I/O request.
Within the locality calculation additional knowledge about the underlying vdev
is considered such as; is the device backing the vdev a rotating media device.
This results in performance increases across the board as well as significant
increases for predominantly streaming loads and for configurations which don't
have evenly performing devices.
The following are results from a setup with 3 Way Mirror with 2 x HD's and
1 x SSD from a basic test running multiple parrallel dd's.
With pre-fetch disabled (vfs.zfs.prefetch_disable=1):
== Stripe Balanced (default) ==
Read 15360MB using bs: 1048576, readers: 3, took 161 seconds @ 95 MB/s
== Load Balanced (zfslinux) ==
Read 15360MB using bs: 1048576, readers: 3, took 297 seconds @ 51 MB/s
== Load Balanced (locality freebsd) ==
Read 15360MB using bs: 1048576, readers: 3, took 54 seconds @ 284 MB/s
With pre-fetch enabled (vfs.zfs.prefetch_disable=0):
== Stripe Balanced (default) ==
Read 15360MB using bs: 1048576, readers: 3, took 91 seconds @ 168 MB/s
== Load Balanced (zfslinux) ==
Read 15360MB using bs: 1048576, readers: 3, took 108 seconds @ 142 MB/s
== Load Balanced (locality freebsd) ==
Read 15360MB using bs: 1048576, readers: 3, took 48 seconds @ 320 MB/s
In addition to the performance changes the code was also restructured, with
the help of Justin Gibbs, to provide a more logical flow which also ensures
vdevs loads are only calculated from the set of valid candidates.
The following additional sysctls where added to allow the administrator
to tune the behaviour of the load algorithm:
* vfs.zfs.vdev.mirror.rotating_inc
* vfs.zfs.vdev.mirror.rotating_seek_inc
* vfs.zfs.vdev.mirror.rotating_seek_offset
* vfs.zfs.vdev.mirror.non_rotating_inc
* vfs.zfs.vdev.mirror.non_rotating_seek_inc
These changes where based on work started by the zfsonlinux developers:
https://github.com/zfsonlinux/zfs/pull/1487
Reviewed by: gibbs, mav, will
MFC after: 2 weeks
Sponsored by: Multiplay
When safety requirements are met, it allows to avoid passing I/O requests
to GEOM g_up/g_down thread, executing them directly in the caller context.
That allows to avoid CPU bottlenecks in g_up/g_down threads, plus avoid
several context switches per I/O.
The defined now safety requirements are:
- caller should not hold any locks and should be reenterable;
- callee should not depend on GEOM dual-threaded concurency semantics;
- on the way down, if request is unmapped while callee doesn't support it,
the context should be sleepable;
- kernel thread stack usage should be below 50%.
To keep compatibility with GEOM classes not meeting above requirements
new provider and consumer flags added:
- G_CF_DIRECT_SEND -- consumer code meets caller requirements (request);
- G_CF_DIRECT_RECEIVE -- consumer code meets callee requirements (done);
- G_PF_DIRECT_SEND -- provider code meets caller requirements (done);
- G_PF_DIRECT_RECEIVE -- provider code meets callee requirements (request).
Capable GEOM class can set them, allowing direct dispatch in cases where
it is safe. If any of requirements are not met, request is queued to
g_up or g_down thread same as before.
Such GEOM classes were reviewed and updated to support direct dispatch:
CONCAT, DEV, DISK, GATE, MD, MIRROR, MULTIPATH, NOP, PART, RAID, STRIPE,
VFS, ZERO, ZFS::VDEV, ZFS::ZVOL, all classes based on g_slice KPI (LABEL,
MAP, FLASHMAP, etc).
To declare direct completion capability disk(9) KPI got new flag equivalent
to G_PF_DIRECT_SEND -- DISKFLAG_DIRECT_COMPLETION. da(4) and ada(4) disk
drivers got it set now thanks to earlier CAM locking work.
This change more then twice increases peak block storage performance on
systems with manu CPUs, together with earlier CAM locking changes reaching
more then 1 million IOPS (512 byte raw reads from 16 SATA SSDs on 4 HBAs to
256 user-level threads).
Sponsored by: iXsystems, Inc.
MFC after: 2 months
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
While these operations are not really needed otherwise, at least for SCSI
they may cause extra errors if some other initiator holds write exclusive
reservation on the LUN (SYNCHRONIZE CACHE handled as "write" operation).
Ensure that d_delmaxsize is always set, removing init to 0 which could cause
future issues if use cases change.
Allow kern.cam.da.X.delete_max (which maps to d_delmaxsize) to be increased
up to the calculated max after being reduced.
MFC after: 1 day
X-MFC-With: r249940
While GEOM in general has provider opened while sending BIO_GETATTR,
GEOM DISK does not really need to open disk to read medium-unrelated
attributes for own use.
Proposed by: ken
Re-ordered SSD quirks alphabetically so they are easier to maintain.
Removed my email and PR reference from comments on each quirk.
Added quirks for more SSDs:
* Crucial M4
* Corsair Force GT
* Intel 520 Series
* Kingston E100 Series
* Samsung 830 Series
Reviewed by: pjd (mentor)
Approved by: pjd (mentor)
MFC after: 1 week
This prevents users from selecting a delete method which may cause
corruption e.g. MPS WS16 on pre P14 firmware.
Reviewed by: pjd (mentor)
Approved by: pjd (mentor)
MFC after: 2 days
- remove DA_FLAG_SAW_MEDIA flag, almost opposite to DA_FLAG_PACK_INVALID,
using the last instead.
- allow opening device with no media present, reporting zero media size
and non-zero sector size, as geom/notes suggests. That allow to read
device attributes and potentially do other things, not related to media.
to query ATA functionality via ATA Pass-Through (16) as this page is defined
as "must" for SATL devices, hence indicating that the device is at least
likely to support Pass-Through (16).
This eliminates errors produced by CTL when ATA Pass-Through (16) fails.
Switch ATA probe daerror call to SF_NO_PRINT to avoid errors printing out
for devices which return invalid errors.
Output details about supported and choosen delete method when verbose booted.
Reviewed by: mav
Approved by: pjd (mentor)
MFC after: 1 week
Ensure that delete_available is reset so re-probes after a media change,
to one with different delete characteristics, will result in the correct
methods being flagged as available.
Make all ccb state changes use a consistent flow:
* free()
* xpt_release_ccb()
* softc->state = <new state>
* xpt_schedule()
Reviewed by: mav
Approved by: pjd (mentor)
MFC after: 1 week
Remove ADA_FLAG_PACK_INVALID flag. Since ATA disks have no concept of media
change it only duplicates CAM_PERIPH_INVALID flag, so we can use last one.
Slightly cleanup DA_FLAG_PACK_INVALID use.
requests.
sys/geom/geom_disk.h:
- Added d_delmaxsize which represents the maximum size of individual
device delete requests in bytes. This can be used by devices to
inform geom of their size limitations regarding delete operations
which are generally different from the read / write limits as data
is not usually transferred from the host to physical device.
sys/geom/geom_disk.c:
- Use new d_delmaxsize to calculate the size of chunks passed through to
the underlying strategy during deletes instead of using read / write
optimised values. This defaults to d_maxsize if unset (0).
- Moved d_maxsize default up so it can be used to default d_delmaxsize
sys/cam/ata/ata_da.c:
- Added d_delmaxsize calculations for TRIM and CFA
sys/cam/scsi/scsi_da.c:
- Added re-calculation of d_delmaxsize whenever delete_method is set.
- Added kern.cam.da.X.delete_max sysctl which allows the max size for
delete requests to be limited. This is useful in preventing timeouts
on devices who's delete methods are slow. It should be noted that
this limit is reset then the device delete method is changed and
that it can only be lowered not increased from the device max.
Reviewed by: mav
Approved by: pjd (mentor)
maximum sizes for said methods, which are used when processing BIO_DELETE
requests. This includes updating UNMAP support discovery to be based on
SBC-3 T10/1799-D Revision 31 specification.
Added ATA TRIM support to cam scsi devices via ATA Pass-Through(16)
sys/cam/scsi/scsi_da.c:
- Added ATA Data Set Management TRIM support via ATA Pass-Through(16)
as a delete_method
- Added four new probe states used to identity available methods and their
limits for the processing of BIO_DELETE commands via both UNMAP and the
new ATA TRIM commands.
- Renamed Probe states to better indicate their use
- Added delete method descriptions used when informing user of issues.
- Added automatic calculation of the optimum delete mode based on which
method presents the largest maximum request size as this is most likely
to result in the best performance.
- Added WRITE SAME max block limits
- Updated UNMAP range generation to mirror that used by ATA TRIM, this
optimises the generation of ranges and fixes a potential overflow
issue in the count when combining multiple BIO_DELETE requests
- Added output of warnings about short deletes. This should only ever
be triggered on devices that fail to correctly advertise their supported
delete modes / max sizes.
- Fixed WS16 requests being incorrectly limited to 65535 in length.
Reviewed by: mav
Approved by: pjd (mentor)
MFC after: 2 weeks
CAM. This can significantly improve performance particularly for SSDs
which don't suffer from seek latencies.
The sysctl / tunable kern.cam.sort_io_queues provides the systems default
setting where:-
0 = queued BIOs are NOT sorted
1 = queued BIOs are sorted (default)
Each device gets its own sysctl kern.cam.<type>.<id>.sort_io_queue
Valid values are:-
-1 = use system default (default)
0 = queued BIOs are NOT sorted
1 = queued BIOs are sorted
Note: Additional patch will look to add automatic use of none sorted queues
for none rotating media e.g. SSD's
Reviewed by: scottl
Approved by: pjd (mentor)
MFC after: 2 weeks
but execute the commands in regular way. There is no any reason to cook CPU
while the system is still fully operational. After this change polling in
CAM is used only for kernel dumping.
driver's periphs, acquiring and releaseing periph references while doing it.
Use it to iterate over the lists of ada and da periphs when flushing caches
and putting devices to sleep on shutdown and suspend. Previous code could
panic in theory if some device disappear in the middle of the process.
The vnode-backed md(4) has to map the unmapped bio because VOP_READ()
and VOP_WRITE() interfaces do not allow to pass unmapped requests to
the filesystem. Vnode-backed md(4) uses pbufs instead of relying on
the bio_transient_map, to avoid usual md deadlock.
Sponsored by: The FreeBSD Foundation
Tested by: pho, scottl
PREVENT ALLOW MEDIUM REMOVAL commands return errors on these devices
without returning sense data. In some cases unrelated following commands
start to return errors too, that makes device to be dropped by CAM.
to avoid sending extra READ CAPACITY requests by dastart(). Schedule periph
again on reprobe completion, or otherwise it may stuck indefinitely long.
This should fix USB explore thread hanging on device unplug, waiting for
periph destruction.
Reported by: hselasky
and da_default_timeout where their current hardcoded values matched the current
default value for said tunables.
PR: kern/169976
Reviewed by: pjd (mentor)
Approved by: mav
DISKFLAG_CANDELETE. While this change makes this layer consistent
other layers such as UFS and ZFS BIO_DELETE support may not notice
any change made manually via these device sysctls until the device
is reopened via a mount.
Also corrected var order in dadeletemethodsysctl
PR: kern/169801
Reviewed by: pjd (mentor)
Approved by: mav
MFC after: 2 weeks
