more obvious imprecision in the previous top changes.
Specifically, top uses a delta of clock_gettime() calls right after
invoking the kern.proc sysctl to fetch the process/thread list to
compute the time delta between the fetches. However, the kern.proc
sysctl handler does not run in constant time. It can spin on locks,
be preempted by an interrupt handler, etc. As a result, the time
between the gathering of stats for individual processes or threads
between subsequent kern.proc handlers can vary. If a "slow" kern.proc
run is followed by a "fast" kern.proc run, then the threads/processes
at the start of the "slow" run will have a longer time delta than the
threads/processes at the end. If the clock_gettime() time delta is
not itself skewed by preemption, then the delta may be too short for
a given thread/process resulting in a higher percent CPU than actual.
However, there is no good way to calculate the exact amount of overage,
nor to know which threads to subtract the overage from. Instead, just
punt and fix the definitely-wrong case of an individual thread having
more than 100% CPU.
Discussed with: zonk
displays after a pause, use the difference in runtime divided by the
length of the pause as the percentage of CPU used instead of the value
calculated by the kernel. In addition, when determing if a process or
thread is idle or not, treat any process or thread that has used any
runtime or performed any context switches during the interval as busy.
Note that the percent CPU is calculated as a double and stored in an
array to avoid recalculating the value multiple times in the comparison
method used to sort processes in the CPU display.
Tested by: Jamie Landeg-Jones <jamie@dyslexicfish.net>
Reviewed by: emaste (earlier version)
MFC after: 1 week
to 999.99% CPU. It still won't be aligned if you have a multithreaded
process using more than 1000% CPU (e.g. idle process on an idle 12-way
system), but 100% is a common case.
Submitted by: Jeremy Chadwick (partial)
MFC after: 1 week
in the manpage by having it display the current CPU (ki_oncpu) rather
than the previously used CPU (ki_lastcpu). ki_lastcpu is still used for
all other thread states.
Reported by: Chris Ross <cross+freebsd@distal.com>
MFC after: 1 week
cmdlengthdelta is the size of the header and we were using it to
allocate a buffer to store the command line. This would mean that
the cmdbuf could be too short. In practice this was never noticed unless
you usually run top -a. On a stock FreeBSD system you can see the
problem by running sendmail and then running top -a on a big terminal
window. In practice this doubles to size available to cmdbuf since the
header is around 65-68 bytes.
Reviewed by: adrian
usage on hosts using ZFS. The new line displays the total amount of RAM
used by the ARC along with the size of MFU, MRU, anonymous (in flight),
headers, and other (miscellaneous) sub-categories. The line is not
displayed on systems that are not using ZFS.
Reviewed by: avg, fs@
MFC after: 3 days
to the maximum number of CPUs to ensure that lcpustates[] array is always
allocated to the maximum size. Previously, if top was started without
per-CPU stats it would allocate a smaller lcpustates[] array. When
per-CPU stats were then enabled, it would overflow the array and trash
the cpustates_columns[] array causing the CPU stats to be printed in the
wrong locations.
Approved by: re (kib)
MFC after: 1 week
ki_rusage member when KERN_PROC_INC_THREAD is passed to one of the
process sysctls.
- Correctly account for the current thread's cputime in the thread when
doing the runtime fixup in calcru().
- Use TIDs as the key to lookup the previous thread to compute IO stat
deltas in IO mode in top when thread display is enabled.
Reviewed by: kib
Approved by: re (kib)
rather than at the bottom of the manpage.
- Remove an obsolete comment about SWAIT being a stale state. It was
resurrected for a different purpose in FreeBSD 5 to mark idle ithreads.
- Add a comment documenting that the SLEEP and LOCK states typically
display the name of the event being waited on with lock names being
prefixed with an asterisk and sleep event names not having a prefix.
MFC after: 1 week
idle threads). The process is displayed by default (subject to whether or
not system processes are displayed) to preserve existing behavior. The
system idle process can be hidden via the '-z' command line argument or the
'z' key while top is running. When it is hidden, top more closely matches
the behavior of FreeBSD <= 4.x where idle time was not accounted to any
process.
MFC after: 2 weeks
