- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

- Add new machine parsable KTR macros for timing events.
- Use this new format to automatically handle syscalls and VOPs. This
changes the earlier format but is still human readable.

Sponsored by: EMC / Isilon Storage Division

- Implement run-time expansion of the KTR buffer via sysctl.
- Implement a function to ensure that all preempted threads have switched
back out at least once. Use this to make sure there are no stale
references to the old ktr_buf or the lock profiling buffers before
updating them.

Reviewed by: marius (sparc64 parts), attilio (earlier patch)
Sponsored by: EMC / Isilon Storage Division

etire the cpumask_t type and replace it with cpuset_t usage.

This is intended to fix the bug where cpu mask objects are
capped to 32. MAXCPU, then, can now arbitrarely bumped to whatever
value. Anyway, as long as several structures in the kernel are
statically allocated and sized as MAXCPU, it is suggested to keep it
as low as possible for the time being.

Technical notes on this commit itself:
- More functions to handle with cpuset_t objects are introduced.
The most notable are cpusetobj_ffs() (which calculates a ffs(3)
for a cpuset_t object), cpusetobj_strprint() (which prepares a string
representing a cpuset_t object) and cpusetobj_strscan() (which
creates a valid cpuset_t starting from a string representation).
- pc_cpumask and pc_other_cpus are target to be removed soon.
With the moving from cpumask_t to cpuset_t they are now inefficient
and not really useful. Anyway, for the time being, please note that
access to pcpu datas is protected by sched_pin() in order to avoid
migrating the CPU while reading more than one (possible) word
- Please note that size of cpuset_t objects may differ between kernel
and userland. While this is not directly related to the patch itself,
it is good to understand that concept and possibly use the patch
as a reference on how to deal with cpuset_t objects in userland, when
accessing kernland members.
- KTR_CPUMASK is changed and now is represented through a string, to be
set as the example reported in NOTES.

Please additively note that no MAXCPU is bumped in this patch, but
private testing has been done until to MAXCPU=128 on a real 8x8x2(htt)
machine (amd64).

Please note that the FreeBSD version is not yet bumped because of
the upcoming pcpu changes. However, note that this patch is not
targeted for MFC.

People to thank for the time spent on this patch:
- sbruno, pluknet and Nicholas Esborn (nick AT desert DOT net) tested
several revision of the patches and really helped in improving
stability of this work.
- marius fixed several bugs in the sparc64 implementation and reviewed
patches related to ktr.
- jeff and jhb discussed the basic approach followed.
- kib and marcel made targeted review on some specific part of the
patch.
- marius, art, nwhitehorn and andreast reviewed MD specific part of
the patch.
- marius, andreast, gonzo, nwhitehorn and jceel tested MD specific
implementations of the patch.
- Other people have made contributions on other patches that have been
already committed and have been listed separately.

Companies that should be mentioned for having participated at several
degrees:
- Yahoo! for having offered the machines used for testing on big
count of CPUs.
- The FreeBSD Foundation for having sponsored my devsummit attendance,
which has been instrumental.
- Sandvine for having offered offices and infrastructure during
development.

(I really hope I didn't forget anyone, if it happened I apologize in
advance).

Remove extra commas from KTR_EVENT4() macro to match number of CTR6() args.
Comparing to other macros there should be strings concatenation, not a
separate arguments.

KTR_CTx are long time aliased by existing classes so they can't serve
their purpose anymore. Axe them out.

Sponsored by: Sandvine Incorporated
Discussed with: jhb, emaste
Possible MFC: TBD

In non-debugging mode make this define (void)0 instead of nothing. This
helps to catch bugs like the below with clang.

if (cond); <--- note the trailing ;
something();

Approved by: ed (mentor)
Discussed on: current@

Grab KTR_SPARE1 and KTR_SPARE5 for KTR_INET and KTR_INET6
respectively, as placeholder for future use of CTR() by
the networking code (MLDv2 will be going in shortly).
Mark KTR_SPARE* as being used in fact by cxgb (picked up
on a 'make universe' run).

- Implement generic macros for producing KTR records that are compatible
with src/tools/sched/schedgraph.py. This allows developers to quickly
create a graphical view of ktr data for any resource in the system.
- Add sched_tdname() and the pcpu field 'name' for quickly and uniformly
identifying records associated with a thread or cpu.
- Reimplement the KTR_SCHED traces using the new generic facility.

Obtained from: attilio
Discussed with: jhb
Sponsored by: Nokia

Axe KTR_ALQ_MASK now that KTR_WITNESS is off unless you hack an #ifdef
in subr_witness.c. I did add a comment in subr_witness.c noting that
KTR_WITNESS is incompatible with KTR_ALQ.

- Add a new KTR_SUBSYS in place of KTR_SPARE1 to serve as a subsystem
placeholder similar to KTR_DEV. Explain the use of KTR_DEV and
KTR_SUBSYS in a comment as well.
- Retire KTR_WITNESS and instead have KTR_WITNESS default to off but use
KTR_SUBSYS if it is enabled.

Clean up unused or poorly utilized KTR values. Remove KTR_FS, KTR_KGDB,
and KTR_IO as they were never used. Remove KTR_CLK since it was only
used for hardclock firing and use KTR_INTR there instead. Remove
KTR_CRITICAL since it was only used for crit enter/exit and use
KTR_CONTENTION instead.

Extend the scope of #ifndef LOCORE to also cover the prototype of
ktr_tracepoint() and the macros using it. This allows this header
to be included in .S files for obtaining the KTR_* class macros
directly and providing a default value for KTR_COMPILE in case it's
not specified in the kernel config file including defining it to 0
when not using 'options KTR' at all.

Requested by: ru
Reviewed by: ru

Change default KTR_COMPILE from KTR_GEN to KTR_ALL, to match with
manual page.

Reviewed by: jhb, pjd

- Replace the unused KTR_NFS with KTR_VFS. KTR_VFS differs from KTR_VOP
in that KTR_VFS will be hand placed, while KTR_VOP traces the individual
vnode operations and is generated by vnode_if.awk.
- Add a comment describing KTR_VOP.

- I broke binary compat. update KTR_VERSION.

Spotted by: jhb

- Add curthread to the state that ktr is saving. The extra information is
well worth the bloat.
- Change the formatting of 'show ktr' slightly to accommodate the
additional field. Remove a tab from the verbose output and place the
actual trace data after a : so it is more easy to understand which
part is the event and which is part of the record.

Addendum to netchild's C compiler abstraction mega-patch which somehow
have been forgotten in my previous commit.

Submitted by: netchild

- Somehow I mangled KTR_CRITICAL.

Spotted by: ru

- Add a new KTR class for the buffer cache.

- Add KTR_SCHED to produce ktr data for sys/tools/sched/schedgraph.py.

Add basic critical section tracing to KTR using event type KTR_CRITICAL.
This generates a KTR event for each critical section entered and exited.

It would be desirable to also log the filename and line number of the
source entering or exiting the critical section, but this requires
hacking up the critical section API, so I've not done that yet.

Add some basic KTR tracing to busdma on i386. This is likely not
the final set of traces -- someone with more busdma background
will probably want to review and expand this, as well as port to
other platforms. This tracing is sufficient to identify key
busdma events on i386, and in particular to draw attention to
bounce buffering events that may have a substantial performance
impact.

Add KTR_GEOM, which allows tracing of basic GEOM I/O events occuring
in the g_up and g_down threads. Each time a bio is propelled up and
down the stack, an event is generating showing the provider, offset,
and length, as well as thread wakeup and work status information.

Assign KTR flag constants for UMA events and callouts.

Retire the KTR_LOCKMGR bit and use it to log eventhandler messages
instead as KTR_EVH.

- Add support for logging KTR via ALQ. This is optional and enabled by the
KTR_ALQ config option.

Add a new KTR type KTR_CONTENTION, and use it in the mutex code to
log the start and end of periods during which mtx_lock() is waiting
to acquire a sleep mutex. The log message includes the file and
line of both the waiter and the holder.

Reviewed by: jhb, jake

KTR_CT* had one too many trailing zeroes, making KTR_CT5-8 too large for
ktr_mask.

Wrap the arguments to CTR6() in parentheses so that the u_long casts work
properly for arguments that are expressions.

ktr changes to improve performance and make writing a userland utility to
dump the trace buffer feasible.
- Remove KTR_EXTEND. This changes the format of the trace entries when
activated, making writing a userland tool which is not tied to a specific
kernel configuration difficult.
- Use get_cyclecount() for timestamps. nanotime() is much too heavy weight
and requires recursion protection due to ktr traces occuring as a result
of ktr traces. KTR_VERBOSE may still require recursion protection, which
is now conditional on it.
- Allow KTR_CPU to be overridden by MD code. This is so that it is possible
to trace early in startup before pcpu and/or curthread are setup.
- Add a version number for the ktr interface. A userland tool can check this
to detect mismatches.
- Use an array for the parameters to make decoding in userland easier.
- Add file and line recording to the non-extended traces now that the extended
version is no more.

These changes will break gdb macros to decode the extended version of the
trace buffer which are floating around. Users of these macros should either
use the show ktr command in ddb, or use the userland utility which can be run
on a core dump.

Approved by: jhb
Tested on: i386, sparc64

Fix two typos, TR6() and ITR6() need to use CTR6(), not CTR5().

Complete the CTR6 addition (and TR6 and ITR6...)

Add a CTR6, we need it now.

Add a hack to get around the fact that egcs 1.1.2 (which I'm using to build
my powerpc kernels on NetBSD/macppc 1.5) doesn't know of the __func__ macro.

- Replace the unused KTR_IDLELOOP trace class with a new KTR_WITNESS trace
class to trace witness events.
- Make the ktr_cpu field of ktr_entry be a standard field rather than one
present only in the KTR_EXTEND case.
- Move the default definition of KTR_ENTRIES from sys/ktr.h to
kern/kern_ktr.c. It has not been needed in the header file since KTR
was un-inlined.
- Minor include cleanup in kern/kern_ktr.c.
- Fiddle with the ktr_cpumask in ktr_tracepoint() to disable KTR events
on the current CPU while we are processing an event.
- Set the current CPU inside of the critical section to ensure we don't
migrate CPU's after the critical section but before we set the CPU.

Add a new psuedo-KTR trace level KTR_ALL which is a mask of all currently
used KTR levels.

- In the KTR_EXTEND case, use a const char * to point to the passed in
filename insteada of copying the first 32 characters of it.
- Add in const modifiers for the passed in format strings and filenames
and their respective members in the ktr_entry struct.

- Axe unused macros used by BSD/OS in assembly for KTR tracing.
- Add a __printflike() tag to ktr_tracepoint() in the KTR_EXTEND case to
verify the arguments passed to KTR tracepoints.

Implement a unified run queue and adjust priority levels accordingly.

- All processes go into the same array of queues, with different
scheduling classes using different portions of the array. This
allows user processes to have their priorities propogated up into
interrupt thread range if need be.
- I chose 64 run queues as an arbitrary number that is greater than
32. We used to have 4 separate arrays of 32 queues each, so this
may not be optimal. The new run queue code was written with this
in mind; changing the number of run queues only requires changing
constants in runq.h and adjusting the priority levels.
- The new run queue code takes the run queue as a parameter. This
is intended to be used to create per-cpu run queues. Implement
wrappers for compatibility with the old interface which pass in
the global run queue structure.
- Group the priority level, user priority, native priority (before
propogation) and the scheduling class into a struct priority.
- Change any hard coded priority levels that I found to use
symbolic constants (TTIPRI and TTOPRI).
- Remove the curpriority global variable and use that of curproc.
This was used to detect when a process' priority had lowered and
it should yield. We now effectively yield on every interrupt.
- Activate propogate_priority(). It should now have the desired
effect without needing to also propogate the scheduling class.
- Temporarily comment out the call to vm_page_zero_idle() in the
idle loop. It interfered with propogate_priority() because
the idle process needed to do a non-blocking acquire of Giant
and then other processes would try to propogate their priority
onto it. The idle process should not do anything except idle.
vm_page_zero_idle() will return in the form of an idle priority
kernel thread which is woken up at apprioriate times by the vm
system.
- Update struct kinfo_proc to the new priority interface. Deliberately
change its size by adjusting the spare fields. It remained the same
size, but the layout has changed, so userland processes that use it
would parse the data incorrectly. The size constraint should really
be changed to an arbitrary version number. Also add a debug.sizeof
sysctl node for struct kinfo_proc.

- Remove much of the inlining of the KTR tracepoints into a ktr_tracepoint()
function declared in kern_ktr.c. The only inline checks left are the
checks that compare KTR_COMPILE with the supplied mask and thus should
be optimized away into either nothing or a direct call to ktr_tracepoint().
- Move several KTR-related options to opt_ktr.h now that they are only
needed by kern_ktr.c and not by ktr.h.
- Add in the ktr_verbose functionality if KTR_EXTEND is turned on. If the
global variable 'ktr_verbose' is non-zero, then KTR messages will be
dumped to the console. This variable can be set by either kernel code
or via the 'debug.ktr_verbose' sysctl. It defaults to off unless the
KTR_VERBOSE kernel option is specified in which case it defaults to on.
This can be useful when the machine locks up spinning in a loop with
interrupts disabled as you might be able to see what it is doing when it
locks up.

Requested by: phk

Remove an evil conditional nested include of <sys/systm.h>

Convert lockmgr locks from using simple locks to using mutexes.

Add lockdestroy() and appropriate invocations, which corresponds to
lockinit() and must be called to clean up after a lockmgr lock is no
longer needed.

Change "KTR_COMPILE & m" to "KTR_COMPILE & (m)" to allow more flexible
expressions for m.

Use '&' instead of '%' to calculate the new value for ktr_idx.

Add KTR, a facility that logs kernel events in order to to facilitate
debugging.

Acquired from: BSDi (BSD/OS)
Submitted by: dfr, grog, jake, jhb