amd64/101132: Incorrect cpu idle and usage statistics in top and systat programs in SMP 6.1-STABLE/amd64

[Evgeny Larionov]

>Number:         101132
>Category:       amd64
>Synopsis:       Incorrect cpu idle and usage statistics in top and systat programs in SMP 6.1-STABLE/amd64
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-amd64
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Aug 01 01:20:14 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Evgeny Larionov
>Release:        6.1-STABLE
>Organization:
Comlink
>Environment:
FreeBSD test.comlink.khakassia.ru 6.1-STABLE FreeBSD 6.1-STABLE #1: Sat Jul 29 19:18:29 KRAST 2006     lion at test.comlink.khakassia.ru:/usr/obj/usr/src/sys/HOSTING  amd64
>Description:
systat -v and top show incorrect information in SMP 6.1-STABLE under amd64.
When run two program with 100% cpu alocation (using only calculation without idle) on processor with HTT (2 logical processors) top and systat show only not more 50% cpu usage with 50% idle. 

top:
last pid: 52141;  load averages:  1.92,  0.95,  0.40         up 2+14:13:23  09:00:47
71 processes:  3 running, 68 sleeping
CPU states: 46.4% user,  0.0% nice,  0.0% system,  3.6% interrupt, 50.0% idle
Mem: 101M Active, 205M Inact, 106M Wired, 15M Cache, 59M Buf, 2796K Free
Swap: 1500M Total, 204K Used, 1500M Free

  PID USERNAME     THR PRI NICE   SIZE    RES STATE  C   TIME   WCPU COMMAND
52122 root           1 113    0  2412K   644K RUN    0   1:47 49.07% horse
52124 root           1 112    0  2412K   644K RUN    0   1:34 48.88% horse

systat -v:

 0.1%Sys   0.0%Intr 49.9%User  0.0%Nice 50.0%Idl   210568 inact     1 19: uhc
|    |    |    |    |    |    |    |    |    |      15856 cache     1 27: em0
>How-To-Repeat:
show top or systat -v utilities in FreeBSD 6.1-STABLE amd64 with SMP kernel during high cpu load (two or more runnig programms using only calculation without idle, looped C code for example) and you can see always 50% CPU usage, not more.
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
 >>>>>>>>>>>>>>>>>>>>>>>>>                            2576 free      3 48: twa
                                                           daefr  2000 cpu0: time
 Namei         Name-cache    Dir-cache                     prcfr  2000 cpu1: time
     Calls     hits    %     hits    %                     react
 
 dmesg.boot:
 Copyright (c) 1992-2006 The FreeBSD Project.
 Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
         The Regents of the University of California. All rights reserved.
 FreeBSD 6.1-STABLE #1: Sat Jul 29 19:18:29 KRAST 2006
     lion at test.comlink.khakassia.ru:/usr/obj/usr/src/sys/HOSTING
 Timecounter "i8254" frequency 1193182 Hz quality 0
 CPU: Intel(R) Pentium(R) 4 CPU 3.00GHz (2992.52-MHz K8-class CPU)
   Origin = "GenuineIntel"  Id = 0xf41  Stepping = 1
   Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
   Features2=0x641d<SSE3,RSVD2,MON,DS_CPL,CNTX-ID,CX16,<b14>>
   AMD Features=0x20000800<SYSCALL,LM>
   Logical CPUs per core: 2
 real memory  = 528371712 (503 MB)
 avail memory = 502108160 (478 MB)
 ACPI APIC Table: <A M I  OEMAPIC >
 FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
  cpu0 (BSP): APIC ID:  0
  cpu1 (AP): APIC ID:  1
 ioapic0 <Version 2.0> irqs 0-23 on motherboard
 ioapic1 <Version 2.0> irqs 24-47 on motherboard
 ioapic2 <Version 2.0> irqs 48-71 on motherboard