FC1 2.4.22-1.2199.5.legacy.nptlsmp SMP timer slowdown

[Davide Rossetti]

I'm actively googling this without success... so I try here, before 
resorting to linux-kernel :(


I seem to remember having read something about it in the past, but no 
luck finding it till now... please HELP :)

I'm plagued by a nasty problem on a SuperMicro ServerWorks dual Xeon no 
HT. the system timer slows down like to a crawl. I mean the effect is 
that 'date' reports a backward time. ntp seems not able to compensate. 
It is related to the interaction with a custom developed PCI 66MHz 64bit 
card (PLD APPLICATIONS:5555) card, driven by a very simple char device 
driver.

It's simple consider the card as guilty, but it's running ok on a number 
of other systems, admittedly not ServerWorks, so I'm not sure of 
anything. The card can only be a stresser...

in the driver, the typical code path is:

- drv_ioctl() to read/write MMIO register

  down_interruptible( &(hib[min].i2csem[i2c_index]) )
  ....
  REGW (min, bar, off-0x200, io.cmd);     /* write cmd   */
  ....
  ret = poll_i2c_not_busy ( min, bar, i2c_index );
  ....
  up (&(hib[min].i2csem[i2c_index]));
 

- drv_read()/drv_write() uses DMA


driver is OpenSource so no problem ;)


kernel 2.4.22-1.2199.5.legacy.nptlsmp


processor       : 1
vendor_id       : GenuineIntel
cpu family      : 15
model           : 2
model name      : Intel(R) Xeon(TM) CPU 2.66GHz
stepping        : 5
cpu MHz         : 2665.974
cache size      : 512 KB

           CPU0       CPU1
  0:    1454286    1525524    IO-APIC-edge  timer
  1:       1802       2143    IO-APIC-edge  keyboard
  2:          0          0          XT-PIC  cascade
  5:          0          0          XT-PIC  hib
  8:          1          0    IO-APIC-edge  rtc
 10:          0          0   IO-APIC-level  usb-ohci
 11:          0          0          XT-PIC  hib , hib , hib
 14:    1173150    1236871    IO-APIC-edge  ide0
 15:          2          0    IO-APIC-edge  ide1
 16:         35          0   IO-APIC-level  aic79xx
 17:         35          0   IO-APIC-level  aic79xx
 30:    1250968          0   IO-APIC-level  eth0
NMI:      12271     126463
LOC:    2979940    2979933
ERR:          0
MIS:          0

00:00.0 Host bridge: ServerWorks CNB20-HE Host Bridge (rev 31)
00:00.1 Host bridge: ServerWorks CNB20-HE Host Bridge
00:00.2 Host bridge: ServerWorks CNB20-HE Host Bridge
00:02.0 VGA compatible controller: ATI Technologies Inc Rage XL (rev 27)
00:04.0 Ethernet controller: Intel Corp. 82540EM Gigabit Ethernet 
Controller (rev 02)
00:0f.0 ISA bridge: ServerWorks CSB5 South Bridge (rev 93)
00:0f.1 IDE interface: ServerWorks CSB5 IDE Controller (rev 93)
00:0f.2 USB Controller: ServerWorks OSB4/CSB5 OHCI USB Controller (rev 05)
00:0f.3 Host bridge: ServerWorks GCLE Host Bridge
00:10.0 Host bridge: ServerWorks: Unknown device 0101 (rev 03)
00:10.2 Host bridge: ServerWorks: Unknown device 0101 (rev 03)
00:11.0 Host bridge: ServerWorks: Unknown device 0101 (rev 03)
00:11.2 Host bridge: ServerWorks: Unknown device 0101 (rev 03)
01:02.0 Multimedia video controller: PLD APPLICATIONS: Unknown device 
5555 (rev 58)
01:03.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5703 
Gigabit Ethernet (rev 02)
02:02.0 Multimedia video controller: PLD APPLICATIONS: Unknown device 
5555 (rev 58)
02:03.0 Multimedia video controller: PLD APPLICATIONS: Unknown device 
5555 (rev 58)
03:02.0 Multimedia video controller: PLD APPLICATIONS: Unknown device 
5555 (rev 58)
04:03.0 SCSI storage controller: Adaptec AIC-7902 U320 (rev 03)
04:03.1 SCSI storage controller: Adaptec AIC-7902 U320 (rev 03)