Count consecutive read requests as blocking in CTL for files and ZVOLs.
Technically read requests can be executed in any order or simultaneously
since they are not changing any data. But ZFS prefetcher goes crasy when
it receives consecutive requests from different threads. Since prefetcher
works on level of separate blocks, instead of two consecutive 128K requests
it may receive 32 8K requests in mixed order.
This patch is more workaround then a real fix, and it does not fix all of
prefetcher problems, but it improves sequential read speed by 3-4x times
in some configurations. On the other side it may hurt performance if
some backing store has no prefetch, that is why it is disabled by default
for raw devices.
In addition to r275481 allow threshold notifications work without UNMAP.
While without UNMAP support there is not much initiator can do about it,
the administrator still better be notified about the storage overflow.
Sponsored by: iXsystems, Inc.
Add to CTL support for threshold notifications for file-backed LUNs.
Previously it was supported only for ZVOL-backed LUNs, but now should work
for file-backed LUNs too. Used value in this case is a space occupied by
the backing file, while available value is an available space on file
system. Pool thresholds are still not implemented in this case.
Sponsored by: iXsystems, Inc.
It is implemented for LUNs backed by ZVOLs in "dev" mode and files.
GEOM has no such API, so for LUNs backed by raw devices all LBAs will
be reported as mapped/unknown.
Sponsored by: iXsystems, Inc.
Increase CTL ports limit from 128 to 256 and LUNs limit from 256 to 1024.
After recent optimizations this change is no longer blocked by CTL memory
consumption. Those limits are still not free, but much cheaper now.
Relnotes: yes
Sponsored by: iXsystems, Inc.
Do not pre-allocate UNIT ATTENTIONs storage for every possible initiator.
Abusing ability of major UAs cover minor ones we may not account UAs for
inactive ports. Allocate UAs storage for port and start accounting only
after some initiator from that port fetched its first POWER ON OCCURRED.
This reduces per-LUN CTL memory usage from >1MB to less then 100K.
Do not pre-allocate reservation keys memory for every possible initiator.
In configurations with many ports, like iSCSI, each LUN is typically
accessed only by limited subset of ports. Allocating that memory on
demand allows to reduce CTL memory usage from 5.3MB/LUN to 1.3MB/LUN.
Make CTL core and block backend set success status before initiating last
data move for read commands. Make CAM target and iSCSI frontends detect
such condition and send command status together with data. New I/O flag
allows to skip duplicate status sending on later fe_done() call.
For Fibre Channel this change saves one of three interrupts per read command,
increasing performance from 126K to 160K IOPS. For iSCSI this change saves
one of three PDUs per read command, increasing performance from 1M to 1.2M
IOPS.
Sponsored by: iXsystems, Inc.
Old allocator created significant lock congestion protecting its lists
of preallocated I/Os, while UMA provides much better SMP scalability.
The downside of UMA is lack of reliable preallocation, that could guarantee
successful allocation in non-sleepable environments. But careful code
review shown, that only CAM target frontend really has that requirement.
Fix that making that frontend preallocate and statically bind CTL I/O for
every ATIO/INOT it preallocates any way. That allows to avoid allocations
in hot I/O path. Other frontends either may sleep in allocation context
or can properly handle allocation errors.
On 40-core server with 6 ZVOL-backed LUNs and 7 iSCSI client connections
this change increases peak performance from ~700K to >1M IOPS! Yay! :)
Sponsored by: iXsystems, Inc.
When passing LUN IDs through treat ASCII values as fixed-length, not
interpreating NULLs as EOLs, but converting them to spaces.
SPC-4 does not tell that T10-based IDs should be NULL-terminated/padded.
And while it tells that it should include only ASCII chars (0x20-0x7F),
there are some USB sticks (SanDisk Ultra Fit), that have NULLs inside
the value. Treating NULLs as EOLs there made those LUN IDs non-unique.
In this mode one head is in Active state, supporting all commands, while
another is in Standby state, supporting only minimal LUN discovery subset.
It is still incomplete since Standby state requires reservation support,
which is impossible to do right without having interlink between heads.
But it allows to run some basic experiments.
Change the default log level for iSCSI target from 3 to 1. It should
have been 1 from the beginning; not sure how it ended up at 3.
Sponsored by: The FreeBSD Foundation
Remove residual xpt_release_device() call left after r272406 cleanup.
Excessive release here could trigger use-after-free condition and kernel
panic on LUN 0 disconnect.
Add to CTL support for logical block provisioning threshold notifications.
For ZVOL-backed LUNs this allows to inform initiators if storage's used or
available spaces get above/below the configured thresholds.
Sponsored by: iXsystems, Inc.
With command serialization used in CTL, there are no other commands to abort
when PREEMPT AND ABORT gets to run, so it is practically equal to PREEMPT.
Implement better handling for ENOSPC error for both CTL and CAM.
This makes VMWare VAAI Thin Provisioning Stun primitive activate, pausing
the virtual machine, when backing storage (ZFS pool) is getting overflowed.
