- initialize the pcpu STAILQ in the NUMA case
- don't enqueue the callback task if there isn't sufficient work to be done
Reported by: pho@
Approved by: sbruno@
- Lend priority to preempted threads in epoch_wait to handle the case
in which we've had priority lent to us. Previously we borrowed the
priority of the lowest priority preempted thread. (pointed out by mjg@)
- Don't attempt allocate memory per-domain on powerpc, we don't currently
handle empty sockets (as is the case on jhibbits Talos' board).
- Handle deferred callbacks as pcpu lists and poll the lists periodically.
Currently the interval is 1/hz.
- Drop the thread lock when adaptive spinning. Holding the lock starves
other threads and can even lead to lockups.
- Keep a generation count pcpu so that we don't keep spining if a thread
has left and re-entered an epoch section.
- Actually removed the callback from the callback list so that we don't
double free. Sigh ...
Approved by: sbruno@
Read locking is over used in the kernel to guarantee liveness. This API makes
it easy to provide livenes guarantees without atomics.
Includes epoch_test kernel module to stress test the API.
Documentation will follow initial use case.
Test case and improvements to preemption handling in response to discussion
with mjg@
Reviewed by: imp@, shurd@
Approved by: sbruno@
- Add macros to allow preinitialization of cap_rights_t.
- Convert most commonly used code paths to use preinitialized cap_rights_t.
A 3.6% speedup in fstat was measured with this change.
Reported by: mjg
Reviewed by: oshogbo
Approved by: sbruno
MFC after: 1 month
Evaluate cpu_stdext_feature early to have moved link_elf_ireloc() see
correct flags, most important is SMAP.
Tested by: mjg
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D15367
KTRPOINT() checks both if we are tracing _and_ if we are recursing within
ktrace. The second condition is only ever executed if ktrace is actually
enabled. This change moves the check out of the hot path in to the functions
themselves.
Discussed with mjg@
Reported by: mjg@
Approved by: sbruno@
The entire mechanism is rarely used and is quite not performant due to
atomci ops on the syscall table. It also has added overhead for completely
unrelated syscalls.
Reduce it by avoiding the func calls if possible (which consistutes vast
majority of cases).
Provides about 3% syscall rate speed up for getuid on Broadwell.
If you add a child to a device that has quiet children, we'll
automatically set the quiet flag on the children, and its
children.
This is indended for things like CPU that have a large amount of
repetition in booting that adds nothing.
Boost the priority of user-space threads when they set
their affinity to a core to adjust its frequency. This avoids a situation
where a CPU bound kernel thread with the same affinity is running on a
down-clocked core, and will "block" powerd from up-clocking the core
until the kernel thread yields. This can lead to poor perfomance,
and to things potentially getting stuck on Giant.
Reviewed by: kib (imp reviewed earlier version)
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D15246
The aim is to permit mbuf allocations after a panic without calling into
the page allocator, without imposing any runtime overhead during regular
operation of the system, and without modifying driver code. The approach
taken is to preallocate a number of mbufs and clusters, storing them
in linked lists, and using the lists to back some UMA cache zones. At
panic time, the mbuf and cluster zone pointers are overwritten with
those of the cache zones so that the mbuf allocator returns
preallocated items.
Using this scheme, drivers which cache mbuf zone pointers from
m_getzone() require special handling when implementing netdump support.
Reviewed by: cem (earlier version), julian, sbruno
MFC after: 1 month
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D15251
For most buses all children are equal, so the order does not matter.
Other buses, such as acpi, carefully order their child devices to
express implicit dependencies between them. For such buses it is safer
to bring down devices in the reverse order.
I believe that this is the reason why hpet_suspend had to be disabled.
Some drivers depend on a working event timer until they are suspended.
But previously we would suspend hpet very early.
I tested this change by makinbg hpet_suspend actually stop HPET timers
and tested that too.
Note that this change is not a complete solution as it does not take
into account bus passes.
A better approach would be to track the actual attach order of the
devices and to use the reverse of that.
Reviewed by: imp, mav
MFC after: 3 weeks
Differential Revision: https://reviews.freebsd.org/D15291
by doing most of the work in a new function prison_add_vfs in kern_jail.c
Now a jail-enabled filesystem need only mark itself with VFCF_JAIL, and
the rest is taken care of. This includes adding a jail parameter like
allow.mount.foofs, and a sysctl like security.jail.mount_foofs_allowed.
Both of these used to be a static list of known filesystems, with
predefined permission bits.
Reviewed by: kib
Differential Revision: D14681
With r332974, when performing a synchronized access of a page's "queue"
field, one must first check whether the page is logically dequeued. If
so, then the page lock does not prevent the page from being removed
from its page queue. Intoduce vm_page_queue(), which returns the page's
logical queue index. In some cases, direct access to the "queue" field
is still required, but such accesses should be confined to sys/vm.
Reported and tested by: pho
Reviewed by: kib
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D15280
x dup_before
+ dup_after
+------------------------------------------------------------+
| x + |
|x x x x ++ ++|
| |____AM___| |AM||
+------------------------------------------------------------+
N Min Max Median Avg Stddev
x 5 1.514954e+08 1.5230351e+08 1.5206157e+08 1.5199371e+08 341205.71
+ 5 1.5494336e+08 1.5519569e+08 1.5511982e+08 1.5508323e+08 96232.829
Difference at 95.0% confidence
3.08952e+06 +/- 365604
2.03266% +/- 0.245071%
(Student's t, pooled s = 250681)
Reported by: mjg@
MFC after: 1 week
Required MD bits are only provided for x86.
Reviewed by: jhb (previous version, as part of the larger patch)
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D13838
Multicast incorrectly calls in to drivers with a mutex held causing drivers
to have to go through all manner of contortions to use a non sleepable lock.
Serialize multicast updates instead.
Submitted by: mmacy <mmacy@mattmacy.io>
Reviewed by: shurd, sbruno
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D14969
Dumpers may wish to print messages from an initialization hook; this
change ensures that such messages aren't mixed with output from the
generic dump code.
MFC after: 1 week
Previously it was possible to connect a socket (which had the
CAP_CONNECT right) by calling "connectat(AT_FDCWD, ...)" even in
capabilties mode. This combination should be treated the same as a call
to connect (i.e. forbidden in capabilities mode). Similarly for bindat.
Disable connectat/bindat with AT_FDCWD in capabilities mode, fix up the
documentation and add tests.
PR: 222632
Submitted by: Jan Kokemüller <jan.kokemueller@gmail.com>
Reviewed by: Domagoj Stolfa
MFC after: 1 week
Relnotes: Yes
Differential Revision: https://reviews.freebsd.org/D15221
While here predict false.
Note the code is wrong (regardless of this change). Dereference of the
pointer can race with module unload. A fix would set the probe to a
nop stub instead of NULL.
Currently both the page lock and a page queue lock must be held in
order to enqueue, dequeue or requeue a page in a given page queue.
The queue locks are a scalability bottleneck in many workloads. This
change reduces page queue lock contention by batching queue operations.
To detangle the page and page queue locks, per-CPU batch queues are
used to reference pages with pending queue operations. The requested
operation is encoded in the page's aflags field with the page lock
held, after which the page is enqueued for a deferred batch operation.
Page queue scans are similarly optimized to minimize the amount of
work performed with a page queue lock held.
Reviewed by: kib, jeff (previous versions)
Tested by: pho
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D14893
To totally silence and ignore secondary kassert violations after a primary
panic, set debug.kassert.do_log=0 and debug.kassert.suppress_in_panic=1.
Additional assertion warnings shouldn't block core dump and may alert the
developer to another erroneous condition. Secondary stack traces may be
printed, identically to the unsuppressed case where panic() is reentered --
controlled via debug.trace_all_panics.
Sponsored by: Dell EMC Isilon
This has been an (incorrect) copy-paste duplicate of debug.kassert.warn_only
since it was originally committed in r243980.
Sponsored by: Dell EMC Isilon
To diagnose and fix secondary panics, it is useful to have a stack trace.
When panic tracing is enabled, optionally trace secondary panics as well.
The option is configured with the tunable/sysctl debug.trace_all_panics.
(The original concern that inspired only tracing the primary panic was
likely that the secondary trace may scroll the original panic message or trace
off the screen. This is less of a concern for serial consoles with logging.
Not everything has a serial console, though, so the behavior is optional.)
Discussed with: jhb
Sponsored by: Dell EMC Isilon
assertions to not suppressing post-panic assertions.
There are some post-panic assertions that are valuable and we shouldn't
default to disabling them. However, when a user trips over them, the
user can still adjust the tunable/sysctl to suppress them temporarily to
get conduct troubleshooting (e.g. get a core dump).
Reported by: cem, markj
r313683 introduced new lockmgr APIs that missed the panic-time neutering
present in the rest of our locks. Correct that by adding the usual check.
Additionally, move the __lockmgr_args neutering above the assertions at the
top of the function. Drop the interlock unlock because we shouldn't have
an unneutered interlock either. No point trying to unlock it.
PR: 227749
Reported by: jtl
Sponsored by: Dell EMC Isilon
Each malloc/free was testing dtrace_malloc_enabled and forcing
extra reads from the malloc type struct to see if perhaps a
dtmalloc probe was on.
Treat it like lockstat and sdt: have a global bolean.
malloc was showing at the top of profile during while running microbenchmarks.
#define DTMALLOC_PROBE_MAX 2
struct malloc_type_internal {
uint32_t mti_probes[DTMALLOC_PROBE_MAX];
u_char mti_zone;
struct malloc_type_stats mti_stats[MAXCPU];
};
Reading mti_zone it wastes a cacheline to hold mti_probes + mti_zone
(which we know is 0) + part of malloc stats of the first cpu which on top
induces false-sharing.
In particular will-it-scale lock1_processes -t 128 -s 10:
before: average:45879692
after: average:51655596
Note the counters can be padded but the right fix is to move them to
counter(9), leaving the struct read-only after creation (modulo dtrace
probes).
This patch adds a new socket option, SO_REUSEPORT_LB, which allow multiple
programs or threads to bind to the same port and incoming connections will be
load balanced using a hash function.
Most of the code was copied from a similar patch for DragonflyBSD.
However, in DragonflyBSD, load balancing is a global on/off setting and can not
be set per socket. This patch allows for simultaneous use of both the current
SO_REUSEPORT and the new SO_REUSEPORT_LB options on the same system.
Required changes to structures
Globally change so_options from 16 to 32 bit value to allow for more options.
Add hashtable in pcbinfo to hold all SO_REUSEPORT_LB sockets.
Limitations
As DragonflyBSD, a load balance group is limited to 256 pcbs
(256 programs or threads sharing the same socket).
Submitted by: Johannes Lundberg <johanlun0@gmail.com>
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D11003
This combined with previous changes significantly depessimizes the behaviour
under contentnion.
In particular the lock1_processes test (locking/unlocking separate files)
from the will-it-scale suite was executed with 128 concurrency on a
4-socket Broadwell with 128 hardware threads.
Operations/second (lock+unlock) go from ~750000 to ~45000000 (6000%)
For reference single-process is ~1680000 (i.e. on stock kernel the resulting
perf is less than *half* of the single-threaded run),
Note this still does not really scale all that well as the locks were just
bolted on top of the current implementation. Significant room for improvement
is still here. In particular the top performance fluctuates depending on the
extent of false sharing in given run (which extends beyond the file).
Added chain+lock pairs were not padded w.r.t. cacheline size.
One big ticket item is the hash used for spreading threads: it used to be the
process pid (which basically serialized all threaded ops). Temporarily the
vnode addr was slapped in instead.
Tested by: pho
kproc_suspend_check. In r329612 bufspacedaemon was turned into a thread
of the bufdaemon process causing both to call kproc_suspend_check with the
same proc argument and that function contains the following while loop:
while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
wakeup(&p->p_siglist);
msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "kpsusp", 0);
}
So one thread wakes up the other and the other wakes up the first again,
locking up UP machines on shutdown.
Also register the shutdown handlers with SHUTDOWN_PRI_LAST + 100 so they
run after the syncer has shutdown, because the syncer can cause a
situation where bufdaemon help is needed to proceed.
PR: 227404
Reviewed by: kib
Tested by: cy, rmacklem
1. check if P_ADVLOCK is already set and if so, don't lock to set it
(stolen from DragonFly)
2. when trying for fast path unlock, check that we are doing unlock
first instead of taking the interlock for no reason (e.g. if we want
to *lock*). whilere make it more likely that falling fast path will
not take the interlock either by checking for state
Note the code is severely pessimized both single- and multithreaded.
