Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Get rid of MAXCPU knowledge used for internal needs only. Switch to
dynamic memory allocation to hold per-CPU memory types data (sized to
mp_maxid for UMA, and to mp_maxcpus for malloc to match the kernel).

That fixes libmemstat with arbitrary large MAXCPU values and therefore
eliminates MEMSTAT_ERROR_TOOMANYCPUS error type.

Reviewed by: jhb
Approved by: re (kib)

Add a new column to the output of vmstat -z to indicate the number
of times the system was forced to sleep when requesting a new allocation.

Expand the debugger hook, db_show_uma, to display these results as well.

This has proven to be very useful in out of memory situations when
it is not known why systems have become sluggish or fail in odd ways.

Reviewed by: rwatson alc
Approved by: scottl (mentor) peter
Obtained from: Yahoo Inc.

Fix a comment in memstat.h: errors are associated with memory type lists,
not individual types.

Submitted by: Bryan Venteicher <bryanv at daemoninthecloset dot org>
MFC after: 3 days

Increase the number of CPUs to 32 to suit sun4v.

Reviewed by: rwatson@

Teach libmemstat(3) how to extract malloc(9) statistics using kvm(3),
so that libmemstat can be used to view full memory statistics from
kernel core dumps and /dev/mem. This is provided via a new query
function, memstat_kvm_malloc(), which is also automatically invoked
by memstat_kvm_all(). A kvm handle must be passed in.

This will allow malloc(9)-specific code to be removed from vmstat(8).

Add memstat_kvm_uma(), an implementation of a libmemstat(3) query routine
that knows how to extract UMA(9) allocator statistics from a core dump or
live memory image using kvm(3). The caller is expected to provide the
necessary kvm_t handle, which is then used by libmemstat(3).

With these changes, it is trivially straight forward to re-introduce
vmstat -z support on core dumps, which was lost when UMA was introduced.

In the short term, this requires including vm/ include files that are not
intended for extra-kernel use, requiring in turn some ugliness.

Having decided not to provide a libmemstat(3) error number to text
conversion routine, now change my mind and add one, memstat_strerror(3),
which returns a const char * pointer to a string describing the error,
to be used on the results of memstat_mtl_geterror().

While here, also correct a minor typo in the HISTORY man page.

Pointers on improving ease of internationalization would be
appreciated.

MFC after: 1 day

Introduce more formal error handling for libmemstat(3):

- Define a set of libmemstat(3) error constants, which are used by all
libmemstat(3) methods except for memstat_mtl_alloc(), which allocates
a memory type list and may return ENOMEM via errno.

- Define a per-memory_type_list current error value, which is set when a
call associated with a memory list fails. This requires wrapping a
structure around the queue(9) list head data structure, but this change
is not visible to libmemstat(3) consumers due to using access methods.

- Add a new accessor method, memstat_mtl_geterror() to retrieve the error
number.

- Consistently set the error number in a number of failure modes where
previously some combination of setting errno and printf'ing error
descriptions was used. libmemstat(3) will now no longer print to stdio
under any circumstances. Returns of NULL/-1 for errors remain the
same.

This avoids use of stdio, misuse of error numbers, and should make it
easier to program a libmemstat(3) consumer able to print useful error
messages. Currently, no error-to-string function is provided, as I'm
unsure how to address internationalization concerns.

MFC after: 1 day

UMA supports "secondary" zones, in which a second zone can be layered
on top of a primary zone, sharing the same allocation "keg". When
reporting statistics for zones, do not report the free items in the
keg as part of the free items in the zone, or those free items will
be reported more than once: for the primary zone, and then any
secondary zones off the primary zone. Separately record and maintain
a kegfree statistic, and export via memstat_get_kegfree(), which is
available for use if needed. Since items free'd back to the keg are
not fully initialized, and hence may not actually be available (since
secondary zone ctor-time initialization can fail), this makes some
amount of sense.

This change corrects a bug made visible in the libmemstat(3)
modifications to netstat: mbufs freed back to the keg from the
packet zone would be counted twice, resulting in negative values
being printed in the mbuf free count.

Some further refinement of reporting relating to secondary zones may
still be required.

Reported by: ssouhlal
MFC after: 3 days

Bump MEMSTAT_MAXCALLER to 16. memtop(8) seems to be able to happily
consume that many slots to track snapshot-to-snapshot changes and
running totals. And 16 is a nice round number.

MFC after: 1 week

Add __BEGIN_DECLS and __END_DECLS to make libmemstat(3) more C++-friendly.

MFC after: 1 week

Increase the number of caller memory storage slots from 2 or 4 to
MEMSTAT_MAXCALLER (8), and expose MEMSTAT_MAXCALLER via memstat.h so
that applications can check their assumptions about how many slots
are available.

Remove 'spare' memory storage in struct malloc_type, since we now
don't expose the data structure internals to applications and rely
on accessor methods, this approach to ABI stability isn't required.

MFC after: 7 days

Add libmemstat(3), a library for use by debugging and monitoring
applications in tracking kernel memory statistics. It provides an
abstracted interface to uma(9) and malloc(9) statistics, wrapped
around the recently added binary stream sysctls for the allocators.

Using this interface, it is easy to build monitoring tools, query
specific memory types for usage information, etc. Facilities are
provided for binding caller-provided data to memory types,
incremental updates of memory types, and queries that span multiple
allocators.

Support for additional allocators is (relatively) easy to add.

The API for libmemstat(3) will probably change some over time as
consumers are written, and requirements evolve. It is written to
avoid encoding ABIs for data structure layout into consuming
applications for this reason.

MFC after: 1 week