8.0RC2 "top" statistics seem broken

[Igor Sysoev]

On Tue, Nov 10, 2009 at 04:29:37PM +0100, Ivan Voras wrote:

> Here is what I'm seeing now:
> 
> 
> last pid: 70893;  load averages:  1.70,  1.10,  0.58 
>                                                              up 
> 27+02:59:26  16:23:59
> 134 processes: 3 running, 131 sleeping
> CPU: 94.8% user,  0.0% nice,  4.6% system,  0.6% interrupt,  0.0% idle
> Mem: 309M Active, 48M Inact, 113M Wired, 17M Cache, 60M Buf, 3624K Free
> Swap: 640M Total, 205M Used, 435M Free, 32% Inuse
> 
>    PID USERNAME  THR PRI NICE   SIZE    RES STATE  C   TIME   WCPU COMMAND
>    751 pgsql       1  45    0   159M   556K select 1 249:38  0.00% postgres
>    756 pgsql       1  44    0 25004K   600K select 1  86:31  0.00% postgres
>    754 pgsql       1  44    0   159M  1040K select 1  13:02  0.00% postgres
>    753 pgsql       1  44    0   159M  7868K select 1  10:55  0.00% postgres
>    597 root        1  44    0  3184K   464K select 0   4:49  0.00% syslogd
>    755 pgsql       1  44    0   159M  1432K select 1   4:46  0.00% postgres
>    659 root        1  44    0 62156K  1356K select 1   4:30  0.00% 
> vmware-guestd
>    765 nobody      1   4    0  3236K   192K kqread 1   3:25  0.00% memcached
>    775 root        1  44    0  9996K   340K select 1   2:18  0.00% httpd
>    900 sveb        1   5    0  9452K     0K select 0   1:49  0.00% <sshd>
>    790 www         1  44    0  9768K   224K select 1   1:47  0.00% httpd
> 70851 ivoras      3  96    0   199M   195M CPU0   0   1:47  0.00% 7z
> 
> 
> Load average and %CPU user are right, as are other global statistics. 
> The load is produced by the "7z" process (archivers/p7zip) which 
> compresses some data in two threads but is credited with 0% CPU, though 
> its runtime is correct (increments every second as it should in a 
> CPU-bound process). It doesn't help if I expand / show individual threads.

I believe this is related to multithreaded processes only. I saw this for
intr kernel process. Singlethread processes eat CPU slightly less than
on 7.2, however, I can not say is it statistic errors or real speedup.
I saw the issue on SMP/ULE only and can not say anything about UP and
4BSD scheduler.


-- 
Igor Sysoev
http://sysoev.ru/en/