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

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

New devstat metrics for devstat_compute_statistics():

DSM_TOTAL_DURATION
DSM_TOTAL_DURATION_READ
DSM_TOTAL_DURATION_WRITE
DSM_TOTAL_DURATION_FREE
DSM_TOTAL_DURATION_OTHER
DSM_TOTAL_BUSY_TIME

The devstat(3) manpage claims that only <devstat.h> is needed as a
prerequisite for using this interface. However, the 'statinfo' struct
actually references CPUSTATES from <sys/resource.h>, so in fact it
requires <sys/resource.h> to compile. Use a nested include of
<sys/resource.h> to make the code match the docs.

Reported by: Pietro Cerutti gahr | gahr.ch

Bump the shared library version number of all libraries that have not
been bumped since RELENG_5.

Reviewed by: ru
Approved by: re (not needed for commit check but in principle...)

ARGH!

Pointy hat to: phk

Commit ken@' changes to this file: Bump version and append new entries
to stay backwards compatible.

Add more devstat calculations, mostly filling in holes, but also adding
a couple of reqests: DSM_BUSY_PCT and DSM_QUEUE_LENGTH.

I have no further plans for mutilating this API at this point in
time, and will update the man-page to reflect current reality as
the next thing.

Reviewed by: ken

Run a revision of the devstat interface:

Kernel:

Change statistics to use the *uptime() timescale (ie: relative to
boottime) rather than the UTC aligned timescale. This makes the
device statistics code oblivious to clock steps.

Change timestamps to bintime format, they are cheaper.

Remove the "busy_count", and replace it with two counter fields:
"start_count" and "end_count", which are updated in the down and
up paths respectively. This removes the locking constraint on
devstat.

Add a timestamp argument to devstat_start_transaction(), this will
normally be a timestamp set by the *_bio() function in bp->bio_t0.
Use this field to calculate duration of I/O operations.

Add two timestamp arguments to devstat_end_transaction(), one is
the current time, a NULL pointer means "take timestamp yourself",
the other is the timestamp of when this transaction started (see
above).

Change calculation of busy_time to operate on "the salami principle":
Only when we are idle, which we can determine by the start+end
counts being identical, do we update the "busy_from" field in the
down path. In the up path we accumulate the timeslice in busy_time
and update busy_from.

Change the byte_* and num_* fields into two arrays: bytes[] and
operations[].

Userland:

Change the misleading "busy_time" name to be called "snap_time" and
make the time long double since that is what most users need anyway,
fill it using clock_gettime(CLOCK_MONOTONIC) to put it on the same
timescale as the kernel fields.

Change devstat_compute_etime() to operate on struct bintime.

Remove the version 2 legacy interface: the change to bintime makes
compatibility far too expensive.

Fix a bug in systat's "vm" page where boot relative busy times would
be bogus.

Bump __FreeBSD_version to 500107

Review & Collaboration by: ken

Turn on WARNS?= 2 for libdevstat.

Submitted by: "Sergey A. Osokin" <osa@freebsd.org.ru>

Implement compute_stats() in terms of devstat_compute_statistics(). This
gets rid of the duplicated code in compute_stats().

Add a new DSM_SKIP statistic type for devstat_compute_statistics() that
causes the subsequent variable argument to be skipped.

Thanks to Sergey Osokin for coding up my idea/code fragment.

Submitted by: "Sergey A. Osokin" <osa@freebsd.org.ru>

Add some features to libdevstat, and overhaul the interface a bit:

1.) prefix all functions in the library with devstat_ (compatability
functions are available for all functions that were chaned in an
incompatible way, but are deprecated).
2.) Add a pointer to a kvm_t as the first argument to functions that
used to get their information via sysctl; they behave the same
as before when NULL is passed as this argument, otherwise, the
information is obtained via libkvm using the supplied handle.
3.) Add a new function, devstat_compute_statistics(), that is intended
to replace the old compute_stats() function. It offers more
statistics data, and has a more flexible interface.

libdevstat does now require libkvm; a library depedency is added, so
that libkvm only needs to be explicitely specified for statically linked
programs.
The library major version number is bumped.

Submitted by: Sergey A. Osokin <osa@freebsd.org.ru>, ken (3)
Reviewed by: ken

$Id$ -> $FreeBSD$

Change the devstat generation number from an int to a long. The int-sized
generation was causing unaligned access faults on the Alpha.

I have incremented the devstat version number, since this is an interface
change. You'll need to recompile libdevstat, systat, iostat, vmstat and
rpc.rstatd along with your kernel.

Partially Submitted by: Andrew Gallatin <gallatin@cs.duke.edu>

Device statistics library. Used by iostat, vmstat, and systat to
format and analyze the output of the new device statistics sysctls.

Submitted by: "Kenneth D. Merry" <ken@FreeBSD.org>