Allow counters_read(9) to take an optional scratch buffer.

Using a scratch buffer makes it possible to take a consistent snapshot of
per-CPU counters without having to allocate memory.

Makes ddb(4)

Allow counters_read(9) to take an optional scratch buffer.

Using a scratch buffer makes it possible to take a consistent snapshot of
per-CPU counters without having to allocate memory.

Makes ddb(4) show uvmexp command work in OOM situations.

ok kn@, mvs@, cheloha@

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Add a second membar producer into counters_zero(). Now it is
symmetric to counters_read().
OK jmatthew@

spelling

ok gnezdo@ semarie@ mpi@

If you use sys/param.h, you don't need sys/types.h

Always allocate counters memory using type M_COUNTERS.

This makes the API simpler, and is probably more useful than spreading
counters memory other several types, making it harder to track.

Prodded

Always allocate counters memory using type M_COUNTERS.

This makes the API simpler, and is probably more useful than spreading
counters memory other several types, making it harder to track.

Prodded by mpi, ok mpi@ stsp@

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Move the membar in counters_read(). It has to be between reading
the generation number and the counters. In counters_zero() put a
membar after resetting the counters, but before writing the generat

Move the membar in counters_read(). It has to be between reading
the generation number and the counters. In counters_zero() put a
membar after resetting the counters, but before writing the generation
number.
OK mpi@ patrick@

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use ncpusfound to size the percpu allocations.

ncpus is used on half the architectures to indicate the number of
cpus that have been hatched, and is used on them in things like ddb
to figure out how

use ncpusfound to size the percpu allocations.

ncpus is used on half the architectures to indicate the number of
cpus that have been hatched, and is used on them in things like ddb
to figure out how many cpus to shut down again.

ncpusfound is incremented during autoconf on MP machines to show
how big ncpus will probably become. percpu is initted after autoconf
but before cpus are hatched, so this works well.

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avoid using realloc in the name of things that dont work like realloc.

cpumem_realloc and counters_realloc actually allocated new per cpu data
for new cpus, they didnt resize the existing allocation

avoid using realloc in the name of things that dont work like realloc.

cpumem_realloc and counters_realloc actually allocated new per cpu data
for new cpus, they didnt resize the existing allocation.

specifically, this renames cpumem_reallod to cpumem_malloc_ncpus, and
counters_realloc to counters_alloc_ncpus.

ok (and with some fixes by) bluhm@

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non-MP vs MP codepaths were confusingly split between the .c and .h file.
Unify these by placing #ifdef MULTIPROCESSOR inside the functions, then
collapse further to reduce _KERNEL blocks
ok dlg

consistently zero the allocated memory in both the MP and UP cases.

from markus@

add generalised access to per cpu data structures and counters.

both the cpumem and counters api simply allocates memory for each cpu in
the system that can be used for arbitrary per cpu data (via c

add generalised access to per cpu data structures and counters.

both the cpumem and counters api simply allocates memory for each cpu in
the system that can be used for arbitrary per cpu data (via cpumem), or
a versioned set of counters per cpu (counters).

there is an alternate backend for uniprocessor systems that basically
turns the percpu data access into an immediate access to a single
allocation.

there is also support for percpu data structures that are available at
boot time by providing an allocation for the boot cpu. after autoconf,
these allocations have to be resized to provide for all cpus that were
enumerated by boot.

ok mpi@

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