schedulers a bit to ensure more correct handling of priorities and fewer
priority inversions:
- Add two functions to the sched(9) API to handle priority lending:
sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these
functions to ask the scheduler to lend a thread a set priority and to
tell the scheduler when it thinks it is ok for a thread to stop borrowing
priority. The unlend case is slightly complex in that the turnstile code
tells the scheduler what the minimum priority of the thread needs to be
to satisfy the requirements of any other threads blocked on locks owned
by the thread in question. The scheduler then decides where the thread
can go back to normal mode (if it's normal priority is high enough to
satisfy the pending lock requests) or it it should continue to use the
priority specified to the sched_unlend_prio() call. This involves adding
a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag
for priority elevation.
- Schedulers now refuse to lower the priority of a thread that is currently
borrowing another therad's priority.
- If a scheduler changes the priority of a thread that is currently sitting
on a turnstile, it will call a new function turnstile_adjust() to inform
the turnstile code of the change. This function resorts the thread on
the priority list of the turnstile if needed, and if the thread ends up
at the head of the list (due to having the highest priority) and its
priority was raised, then it will propagate that new priority to the
owner of the lock it is blocked on.
Some additional fixes specific to the 4BSD scheduler include:
- Common code for updating the priority of a thread when the user priority
of its associated kse group has been consolidated in a new static
function resetpriority_thread(). One change to this function is that
it will now only adjust the priority of a thread if it already has a
time sharing priority, thus preserving any boosts from a tsleep() until
the thread returns to userland. Also, resetpriority() no longer calls
maybe_resched() on each thread in the group. Instead, the code calling
resetpriority() is responsible for calling resetpriority_thread() on
any threads that need to be updated.
- schedcpu() now uses resetpriority_thread() instead of just calling
sched_prio() directly after it updates a kse group's user priority.
- sched_clock() now uses resetpriority_thread() rather than writing
directly to td_priority.
- sched_nice() now updates all the priorities of the threads after the
group priority has been adjusted.
Discussed with: bde
Reviewed by: ups, jeffr
Tested on: 4bsd, ule
Tested on: i386, alpha, sparc64
- ipx_pcbnotify(), which is never called.
- ipx_rtchange(), which is never called, is incomplete inplemented, and
also #ifdef notdef.
- spx_fixmtu(), which is never called, is incompletely implemented, and
also #ifdef notdef.
other comments. Clarify that the next two things needed for SMP are
two lines.
- Expand mii abbreviation to miibus for clarity in the USB ethernet
comment.
is the case for most other sysctls in the System V IPC message queue
implementation.
PR: 75541
Submitted by: Sergiy Vyshnevetskiy <serg at vostok dot net>
MFC after: 2 weeks
generic bridge support was biting us more than it helped, whenever a new chipset
came out from a vendor and misprogramming it caused strange hangs or corruption.
[2] Add a large number of PCI IDs based on what the linux drivers support.
Note that the new PCI IDs haven't been tested, they're just *likely* to work.
In particular the VIA AGP 8x chipsets are concerning, due to lack of testing,
possible issues (kern/69953), and not having a nice "does this bridge say it
would do 8x" function. However, this shouldn't make the situation worse, since
these chips would have probed in the past anyway.
more general than previous. It also lets me implement cancelable point
in thread library. Also in theory, umtx_lock and umtx_unlock can
be implemented by using umtx_wait and umtx_wake, all atomic operations
can be done in userland without kernel's casuptr() function.
to remove a transaction from the async schedule. The previous method didn't
work well and led to the hardware writing to free'd buffers etc, as
it didn't always know that the transaction had been aborted.
Written after consultation with David Brownell who wrote the Linux
EHCI driver.
As part of this give the sqh structure a "previous" pointer.
MFC after: 1 week
rather than a softc pointer (with the bus structure at the start).
This is a non-functional change. It just helps when reading the code to
know that the ehci, ohci and uhci drivers share the bus structure, not the
entire softc.
of lock types in the kernel. This results in an increase of witness
data usage from ~145k to ~280k on i386 for kernels with
'options WITNESS'.
- Remove the unused witness malloc bucket.
Submitted by: Michal Mertl mime at traveller dot cz (1)
This allows boot to proceed on a real system until the issue
of calling back into certain OpenFirmware calls (e.g. finddevice)
in thread context is understood.
(this commit only affects psim users, of which I think I am the
only one...)
Silence on: net@, current@, hackers@.
No objections: joerg
Requested by: by many (mostly Cronyx) users for a long long time.
MFC after: 10 days
PR: kern/21771, kern/66348
show file name for 'mdconfig -l -u <x>' command.
This allows to preserve API/ABI compatibility with version 0 (that's why
I changed version number back to 0) and will allow to merge this change
to RELENG_5.
MFC after: 5 days
system from an AP at runtime (i.e., calling cpu_reset from ddb). Someday,
if we move to an NMI for stopping cpus instead, we can do away with this.
Requested by: jhb
