Re: Pin-pointing the root of unusual application latencies

[John Sigler <linux.kernel@free.fr>]

Len Brown wrote:

> John Sigler wrote:
> 
>> # cat /proc/interrupts
>>             CPU0
>>    0:         37    XT-PIC-XT        timer
>>    1:          2    XT-PIC-XT        i8042
>>    2:          0    XT-PIC-XT        cascade
>>    7:          0    XT-PIC-XT        acpi
>>   10:        175    XT-PIC-XT        eth2, Dta1xx
>>   11:       1129    XT-PIC-XT        eth0
>>   12:          4    XT-PIC-XT        eth1
>>   14:      21482    XT-PIC-XT        ide0
>> NMI:          0
>> LOC:     161632
>> ERR:          0
>> MIS:          0
>>
>> IRQ 10 is shared between a NIC and an I/O board.
>>
>> For eth2, the kernel said:
>> ACPI: PCI Interrupt 0000:00:0a.0[A] -> Link [LNKC]
>>    -> GSI 10 (level, low) -> IRQ 10
>>
>> For Dta1xx, the kernel said:
>> ACPI: PCI Interrupt 0000:02:0e.0[A] -> Link [LNKC]
>>    -> GSI 10 (level, low) -> IRQ 10
>>
>> Is it possible to avoid the two boards sharing IRQ 10?
> 
> Maybe.  In this configuration, INTA of the two devices
> is physically connected to the same wire on the device-side
> of the interrupt re-mapper -- so you'd have to change the configuration.
> If you have an IOAPIC and can enable it, that will not hurt --

I believe this board does not provide an IO-APIC.
Even the LAPIC is disabled in the BIOS.
(Why would they do that??)

> though unless something else changes, these devices are still
> tied together on the device-side of the mapper.
> So if you can physically move one of the devices to another slot
> that is your best bet.

I will try.

> I'd need a bunch of info from your system to tell you what
> you can do ahead of time, including full dmesg, lspci -vv
> and acpidump.

The motherboard is an Adlink EBC-2000T with 3 on-board Intel 82559 NICs.
http://www.adlinktech.com/PD/web/PD_detail.php?pid=213

VIA Pro133T (VT82C694T + VT82C686B) chipset.
http://www.viaarena.com/default.aspx?PageID=40&STypeID=12

Kernel config:
http://linux.kernel.free.fr/latency/config-2.6.20.7-rt8-adlink-latency

dmesg:
http://linux.kernel.free.fr/latency/dmesg.adlink

lspci:
http://linux.kernel.free.fr/latency/lspci.adlink

acpidump:
http://linux.kernel.free.fr/latency/acpidump.adlink

Regards.