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The problems are that, with the ACPI vs timer overring issue _fixed_,
after using the box for some time (between several seconds and 1 hour, at
random) processes get very high CPU loads (once I've got X using 107% of
the CPU, for example) and the system becomes unresponsive, as though there
were interrupts lost or something similar.
Andreas Herrman reproduced similar problems:
> Ok, now I've reproduced the stability problem.
> - Using tip/master,
> - reverting e38502eb8aa82314d5ab0eba45f50e6790dadd88 and
> - applying your patch from this posting
> http://marc.info/?l=linux-kernel&m=121539354224562&w=4
>
> Starting X, firefox, gimp, tuxpaint and doing some drawing in tuxpaint
> results in a slow system. Drawing is almost not possible anymore --
> Selections of new colors, cursors etc. is performed with huge delay
> if it's performed at all.
>
> BTW, the code sets up timer IRQ as Virtual Wire IRQ:
>
> Jul 8 14:57:58 kodscha IO-APIC (apicid-pin) 2-22, 2-23 not connected.
> Jul 8 14:57:58 kodscha ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
> Jul 8 14:57:58 kodscha ...trying to set up timer as Virtual Wire IRQ... works.
>
> and both INT0 and INT2 of IOAPIC are masked:
>
> Jul 8 14:57:58 kodscha NR Dst Mask Trig IRR Pol Stat Dmod Deli Vect:
> Jul 8 14:57:58 kodscha 00 000 1 0 0 0 0 0 0 00
> Jul 8 14:57:58 kodscha 01 003 0 0 0 0 0 1 1 31
> Jul 8 14:57:58 kodscha 02 003 1 0 0 0 0 0 0 30
>
> I've also seen strange CPU utilization -- with syslog-ng:
>
> top - 15:33:06 up 35 min, 4 users, load average: 1.70, 0.68, 0.37
> Tasks: 64 total, 4 running, 60 sleeping, 0 stopped, 0 zombie
> Cpu0 : 0.0%us,100.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
> Cpu1 : 6.4%us, 87.2%sy, 0.0%ni, 5.8%id, 0.0%wa, 0.6%hi, 0.0%si, 0.0%st
> Mem: 895384k total, 283568k used, 611816k free, 35492k buffers
> Swap: 1959920k total, 0k used, 1959920k free, 163044k cached
>
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> 4632 root 20 0 17216 800 580 S 104 0.1 0:34.22 syslog-ng
> 28505 root 20 0 205m 11m 4024 S 6 1.3 0:21.16 X
> 28518 root 20 0 56292 5652 4492 S 1 0.6 0:01.80 fluxbox
> 1 root 20 0 3724 608 508 S 0 0.1 0:00.36 init
>
> So far I have no clue why C1E-idle in conjunction with virtual wire
> mode causes this strange behaviour.
>
> ... and I start to think about the root cause of all this.
>
> I've performed similar tests under X with the IRQ0/INT0 configuration and
> I did not see above symptoms.
So lets fall back to the IRQ0/INT0 configuration on this box.
This basically restores the dont-use-the-lapic-timer exception mechanism
that was unconditional on this box prior commit 8750bf5 ("x86: add C1E
aware idle function").
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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UV supports really big systems. So big, in fact, that the APICID register
does not contain enough bits to contain an APICID that is unique across all
cpus.
The UV BIOS supports 3 APICID modes:
- legacy mode. This mode uses the old APIC mode where
APICID is in bits [31:24] of the APICID register.
- x2apic mode. This mode is whitebox-compatible. APICIDs
are unique across all cpus. Standard x2apic APIC operations
(Intel-defined) can be used for IPIs. The node identifier
fits within the Intel-defined portion of the APICID register.
- x2apic-uv mode. In this mode, the APICIDs on each node have
unique IDs, but IDs on different node are not unique. For example,
if each mode has 32 cpus, the APICIDs on each node might be
0 - 31. Every node has the same set of IDs.
The UV hub is used to route IPIs/interrupts to the correct node.
Traditional APIC operations WILL NOT WORK.
In x2apic-uv mode, the ACPI tables all contain a full unique ID (note:
exact bit layout still changing but the following is close):
nnnnnnnnnnlc0cch
n = unique node number
l = socket number on board
c = core
h = hyperthread
Only the "lc0cch" bits are written to the APICID register. The remaining bits are
supplied by having the get_apic_id() function "OR" the extra bits into the value
read from the APICID register. (Hmmm.. why not keep the ENTIRE APICID register
in per-cpu data....)
The x2apic-uv mode is recognized by the MADT table containing:
oem_id = "SGI"
oem_table_id = "UV-X"
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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