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
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
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>
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
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>
