is requested. Handle this case specially before the while loop.
- Use the held vnode lock to check for VI_DOOMED. The vnode lock and
interlock must both be held to set VI_DOOMED so either one held, even
shared, is sufficient to check it.
No objection by: kib
vnodes belonging to the mountpoint. Also, yield when in the
softdep_process_worklist() even when we are not going to sleep due to
buffer drain.
It is believed that the ULE fixed the problem [1], but the yielding
seems to be needed at least for the 4BSD case.
Discussed: on stable@, with bde
Reviewed by: tegge, jeff [1]
MFC after: 2 weeks
BO_LOCK/UNLOCK/MTX when manipulating the bufobj.
- Create a new lock in the bufobj to lock bufobj fields independently.
This leaves the vnode interlock as an 'identity' lock while the bufobj
is an io lock. The bufobj lock is ordered before the vnode interlock
and also before the mnt ilock.
- Exploit this new lock order to simplify softdep_check_suspend().
- A few sync related functions are marked with a new XXX to note that
we may not properly interlock against a non-zero bv_cnt when
attempting to sync all vnodes on a mountlist. I do not believe this
race is important. If I'm wrong this will make these locations easier
to find.
Reviewed by: kib (earlier diff)
Tested by: kris, pho (earlier diff)
code.
The bug:
There exists a race condition for timeout/untimeout(9) due to the
way that the softclock thread dequeues timeouts.
The softclock thread sets the c_func and c_arg of the callout to
NULL while holding the callout lock but not Giant. It then drops
the callout lock and acquires Giant.
It is at this point where untimeout(9) on another cpu/thread could
be called.
Since c_arg and c_func are cleared, untimeout(9) does not touch the
callout and returns as if the callout is canceled.
The softclock then tries to acquire Giant and likely blocks due to
the other cpu/thread holding it.
The other cpu/thread then likely deallocates the backing store that
c_arg points to and finishes working and hence drops Giant.
Softclock resumes and acquires giant and calls the function with
the now free'd c_arg and we have corruption/crash.
The fix:
We need to track curr_callout even for timeout(9) (LOCAL_ALLOC)
callouts. We need to free the callout after the softclock processes
it to deal with the race here.
Obtained from: Juniper Networks, iedowse
Reviewed by: jhb, iedowse
MFC After: 2 weeks.
around the check for the BV_BKGRDINPROG in the brelse() and bqrelse().
See the comment for the explanation why it is safe.
Tested by: pho
Submitted by: jeff
to enter thread_suspend_check().
- Set TDF_ASTPENDING along with TDF_NEEDSUSPCHK so we can move the
thread_suspend_check() to ast() rather than userret().
- Check TDF_NEEDSUSPCHK in the sleepq_catch_signals() optimization so
that we don't miss a suspend request. If this is set use the
expensive signal path.
- Set NEEDSUSPCHK when creating a new thread in thr in case the
creating thread is due to be suspended as well but has not yet.
Reviewed by: davidxu (Authored original patch)
resource to a CPU. The default method is to pass the request up to the
parent similar to BUS_CONFIG_INTR() so that all busses don't have to
explicitly implement bus_bind_intr. A bus_bind_intr(9) wrapper routine
similar to bus_setup/teardown_intr() is added for device drivers to use.
Unbinding an interrupt is done by binding it to NOCPU. The IRQ resource
must be allocated, but it can happen in any order with respect to
bus_setup_intr(). Currently it is only supported on amd64 and i386 via
nexus(4) methods that simply call the intr_bind() routine.
Tested by: gallatin
rqindex back in struct thread.
- Compile kern_switch.c independently again and stop #include'ing it from
schedulers.
- Remove the ts_thread backpointers and convert most code to go from
struct thread to struct td_sched.
- Cleanup the ts_flags #define garbage that was causing us to sometimes
do things that expanded to td->td_sched->ts_thread->td_flags in 4BSD.
- Export the kern.sched sysctl node in sysctl.h
thread_fini(). The schedulers initialize themselves properly during
sched_fork_thread() anyhow. fini is only called when we're returning
the memory to the allocator which surely doesn't care what state the
memory is in.
is only used by 4bsd.
- Create a new runq_choose_fuzz() function rather than polluting runq_choose()
with 4BSD specific code.
- Move the fuzz sysctl into sched_4bsd.c
- Remove some dead code from kern_switch.c
maxsockets limit, not maxfiles limit. The question remains why those
limits are handled differently (with error code for maxfiles but with
sleep for maxsokets), but those would be addressed in a separate commit
if necessary.
Requested by: rwhatson, jeff
before doing the very expensive cursig() and related locking. NEEDSIGCHK
is updated whenever our signal mask change or when a signal is delivered and
should be sufficient to avoid the more expensive tests. This eliminates
another source of PROC_LOCK contention in multithreaded programs.
- In the last revision the code was changed to use maxfilesperproc rather than
the per-process file limit to restrict the size of the poll array. This
eliminates a significant source of process lock contention in multithreaded
programs and is cheaper. This had been committed with the wrong batch of
changes.
a simple (wmesg, count) tuple in a hash to keep track of how many times
we sleep at each wait message. We hash on message and not channel. No
line number information is given as typically wait messages are not used in
more than one place. Identical strings defined at different addresses will
show up with seperate counters.
- Use debug.sleepq.enable to enable, .reset to reset, and .stats dumps stats.
- Do an unsynchronized check in sleepq_switch() prior to switching before
calling sleepq_profile() which uses a global lock to synchronize the hash.
Only sleeps which actually cause a context switch are counted.
1.38 in 2001. Break out of the FOREACH_THREAD_IN_PROC loop when we've
discovered a new proc in the chain.
- Increment i and check for maxlockdepth once per matching process not
once per thread. This didn't properly terminate the loop before.
- Fix a bug which has existed potentially since rev 1.1. waitblock->lf_next
can be NULL when a thread has been woken-up but not yet scheduled. Check
for this condition rather than blindly dereferencing.
Found by: libMicro
requiring the per-process spinlock to only requiring the process lock.
- Reflect these changes in the proc.h documentation and consumers throughout
the kernel. This is a substantial reduction in locking cost for these
fields and was made possible by recent changes to threading support.
- Always include the ie_disable and ie_eoi methods in 'struct intr_event'
and collapse down to one intr_event_create() routine. The disable and
eoi hooks simply aren't used currently in the !INTR_FILTER case.
- Expand 'disab' to 'disable' in a few places.
- Use function casts for arm and i386:intr_eoi_src() instead of wrapper
routines since to trim one extra indirection.
Compiled on: {arm,amd64,i386,ia64,ppc,sparc64} x {FILTER, !FILTER}
Tested on: {amd64,i386} x {FILTER, !FILTER}
drivers.
In the giant_XXX wrappers for the device methods of the D_NEEDGIANT
drivers, do not dereference the cdev->si_devsw. It is racing with
the destroy_devl() clearing of the si_devsw. Instead, use the
dev_refthread() and return ENXIO for the destroyed device. [1]
The check for the D_INIT in the prep_cdevsw() was not synchronized with
the call of the fini_cdevsw() in destroy_devl(), that under rapid device
creation/destruction may result in the use of uninitialized cdevsw [2].
Change the protocol for the prep_cdevsw(), requiring it to be called
under dev_mtx, where the check for D_INIT is done.
Do not free the memory allocated for the gianttrick cdevsw while holding
the dev_mtx, put it into the free list to be freed later. Reuse the
d_gianttrick pointer to keep the size and layout of the struct cdevsw
(requested by phk). Free the memory in the dev_unlock_and_free(), and do
all the free after the dev_mtx is dropped (suggested by jhb).
Reported by: bsdimp + many [1], pho [2]
Reviewed by: phk, jhb
Tested by: pho
MFC after: 1 week
uidinfo structure. This entirely removes contention observed on the
ui_mtxp mutex (as it is now gone).
- Convert the uihashtbl_mtx mutex to a rwlock, as most of the time we just
need to read-lock it.
Reviewed by: jhb, jeff, kris & others
Tested by: kris
a jail, etc. by simply calling setpriority(PRIO_PROCESS, <PID>, 0) and
checking the return value: 0 means that the process exists and -1 that
it doesn't exist.
Reviewed by: rwatson
MFC after: 1 week
after each SYSINIT() macro invocation. This makes a number of
lightweight C parsers much happier with the FreeBSD kernel
source, including cflow's prcc and lxr.
MFC after: 1 month
Discussed with: imp, rink
Otherwise the parameter is no-op, since zone by default limits number
of descriptors to some 12K entries. Attempt to allocate more ends up
sleeping on zonelimit.
MFC after: 2 weeks
- Add a new intr_event method ie_assign_cpu() that is invoked when the MI
code wishes to bind an interrupt source to an individual CPU. The MD
code may reject the binding with an error. If an assign_cpu function
is not provided, then the kernel assumes the platform does not support
binding interrupts to CPUs and fails all requests to do so.
- Bind ithreads to CPUs on their next execution loop once an interrupt
event is bound to a CPU. Only shared ithreads are bound. We currently
leave private ithreads for drivers using filters + ithreads in the
INTR_FILTER case unbound.
- A new intr_event_bind() routine is used to bind an interrupt event to
a CPU.
- Implement binding on amd64 and i386 by way of the existing pic_assign_cpu
PIC method.
- For x86, provide a 'intr_bind(IRQ, cpu)' wrapper routine that looks up
an interrupt source and binds its interrupt event to the specified CPU.
MI code can currently (ab)use this by doing:
intr_bind(rman_get_start(irq_res), cpu);
however, I plan to add a truly MI interface (probably a bus_bind_intr(9))
where the implementation in the x86 nexus(4) driver would end up calling
intr_bind() internally.
Requested by: kmacy, gallatin, jeff
Tested on: {amd64, i386} x {regular, INTR_FILTER}
- Close a sleepqueue signal race by interlocking with the per-process
spinlock. This was mistakenly omitted from the thread_lock patch and
has been a race since.
MFC After: 1 week
PR: bin/117603
Reported by: Danny Braniss <danny@cs.huji.ac.il>
While the KSE project was quite successful in bringing threading to
FreeBSD, the M:N approach taken by the kse library was never developed
to its full potential. Backwards compatibility will be provided via
libmap.conf for dynamically linked binaries and static binaries will
be broken.
sched_sleep(). This removes extra thread_lock() acquisition and
allows the scheduler to decide what to do with the static boost.
- Change the priority arguments to cv_* to match sleepq/msleep/etc.
where 0 means no priority change. Catch -1 in cv_broadcastpri() and
convert it to 0 for now.
- Set a flag when sleeping in a way that is compatible with swapping
since direct priority comparisons are meaningless now.
- Add a sysctl to ule, kern.sched.static_boost, that defaults to on which
controls the boost behavior. Turning it off gives better performance
in some workloads but needs more investigation.
- While we're modifying sleepq, change signal and broadcast to both
return with the lock held as the lock was held on enter.
Reviewed by: jhb, peter
tdq_runq_add to select the runq rather than hoping we set it properly
when we adjusted the priority. This involves the same number of
branches as before so should perform identically without the extra
fragility.
Tested by: bz
Reviewed by: bz
- Only calculate timeshare priorities once per tick or when a thread is woken
from sleeping.
- Keep the ts_runq pointer valid after all priority changes.
- Call tdq_runq_add() directly from sched_switch() without passing in via
tdq_add(). We don't need to adjust loads or runqs anymore.
- Sort tdq and ts_sched according to utilization to improve cache behavior.
Sponsored by: Nokia
