Richard McDougall wrote:
Hi Bob,
I've often wanted to see prstat changed to consistently show 'percent of
a CPU core',
so that values might exceed 100 for multi-threaded apps, and so
per-process values
from the same task running on different configurations would be more
comparable.
Can you expand on the scenarios in which you would use this, an how
the information would be interpreted?
Sure. For me, 'scenarios=all'. :-)
On a 72-way system, a single CPU hog shows as 1.4%. On an 8-way system,
it will
show as 12.5%. Absent the context of the core count, it's not obvious
that it's a CPU-
bound process, or that it's using the same absolute CPU resource on
these two systems.
On a (mythical) 250-way system, after rounding to the first decimal, it
would show as
0.0%. I'd rather see it reported as using 100% (of a CPU) in all cases,
without being
personally burdened with the task of dividing by N.
When using '-m' without '-L', I'd like to see that hog/6 is using 400%
CPU without
needing to switch views.
With 32 CPU-bound threads on a T1-based system, I *think* I'd like to
see each one
reported as using 25% (of a core). With CMT, it maybe gets a bit fuzzy?
In other words, I think '%systemwide_cpu' is fundamentally annoying, as
is seeing
'percent of total' (with -m) without seeing 'total' at the same time. I
believe most
people would agree. Am I right -- or just annoying?
Cheers,
-- Bob
Thanks,
Richard.
With '-m', the 'percent of total' concept needs to be maintained, but
maybe adding
another column would help. The issue of units extends to the '-T'
rollups. Some on
this thread have also wished for more 'top-like' outputs from prstat,
such as aggregate
usr/sys/idle. (I can offer free counseling for those who want %wio. ;-) )
Actually, as we evolve to systems architectures with massive thread
counts, we'll
see CPU-bound threads average to 0% with the current implementation. Yikes!
How about '-A' for 'Aggregate' and '-X' for 'eXtended'? I don't want to
file an RFE
until there is some consensus on these notions.
Cheers,
-- Bob
Regards,
Richard.
On Thu, Oct 19, 2006 at 08:34:17AM -0700, Cherian Abraham wrote:
Hi All,
Thanks for all the feedback.
I tried to run both prstat and prstat -m option and here are the output
displays...
(showing only three processes).
prstat -mL
PID USERNAME USR SYS TRP TFL DFL LCK SLP LAT VCX ICX SCL SIG
PROCESS/LWPID 25952 root 30 30 0.0 0.0 0.0 0.0 30 0.0 100 6K 87K
0 processC/1
25571 root 5.1 0.7 0.0 0.0 0.0 0.0 93 0.0 57 68 5K 0 processB/1
2003 root 0.3 1.2 0.1 0.0 0.0 0.0 97 1.9 67 8 1K 21 processA/1
prstat
PID USERNAME SIZE RSS STATE PRI NICE TIME CPU PROCESS/NLWP
2003 root 39M 38M sleep 59 0 3:05:58 0.6% processA/1
25571 root 6488K 5752K sleep 13 0 0:00:00 0.5% processB/1
25952 root 5208K 4184K sleep 23 0 0:00:00 0.1% processC/1
Is it possible to relate the CPU usage shown by prstat and prstat -m ? or
am i comparing apples and oranges here ? process C shows 0.1% CPU usage
(is this only usr time?) and microstate accounting shows 30% user time,
30% sys time and 30% sleep. How does one relate the two ? The above is
just snapshots taken almost at the same time.
My testing is normally done in a 2 hr time frame. So i could run prstat
with 10 sec sampling rate and prstat -m with also a 10 sec sampling rate
during the same period. The sampling instance for both maybe slightly
off. If i average out during this run for each process from prstat and
also the same from prstat -m, how do i relate these values ?
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