Hi,
After reading about problems with ICH5 SATA (Intel 875P) I've
set my BIOS back to normal mode for the SATA controller. So now the SATA
drive appears as hdc instead of hde.
The SATA drive was working in both situations (enhanced/normal) the only
difference is that with normal mode there no high system load caused by
the SATA controller (As I reported in a previous mail).
What's causing the high interrupt count in 'enhanced' mode?
Nb I have seen this on both 2.4.21 and 2.5.73.
Cheers,
Jurgen
Jurgen Kramer wrote:
> Hi,
>
> After reading about problems with ICH5 SATA (Intel 875P) I've
> set my BIOS back to normal mode for the SATA controller. So now the SATA
> drive appears as hdc instead of hde.
>
> The SATA drive was working in both situations (enhanced/normal) the only
> difference is that with normal mode there no high system load caused by
> the SATA controller (As I reported in a previous mail).
>
> What's causing the high interrupt count in 'enhanced' mode?
Well, in legacy mode (a.k.a. normal), each ATA port (a.k.a. channel
a.k.a. bus) gets their own interrupt, which is never shared with another
device.
In native mode (a.k.a. enhanced), two ATA ports share a single PCI
interrupt. Further, this interrupt may be shared with any number of
other PCI devices.
So, high interrupt count is necessarily a worry because you're probably
seeing a coalescing of multiple interrupt counts into one big one.
Jeff
On Tue, 2003-07-01 at 22:41, Jeff Garzik wrote:
> Well, in legacy mode (a.k.a. normal), each ATA port (a.k.a. channel
> a.k.a. bus) gets their own interrupt, which is never shared with another
> device.
>
> In native mode (a.k.a. enhanced), two ATA ports share a single PCI
> interrupt. Further, this interrupt may be shared with any number of
> other PCI devices.
>
> So, high interrupt count is necessarily a worry because you're probably
> seeing a coalescing of multiple interrupt counts into one big one.
>
> Jeff
Hmm, it still looks like this is a driver problem. Because
a) your SCSI-ATA driver doesn't show this behavior..;-)
b) booting to XP also doesn't show this behavior.
BTW it seems that all ATA ports have their own interrupt:
CPU0 CPU1
0: 52132 52728 IO-APIC-edge timer
1: 2 2 IO-APIC-edge keyboard
2: 0 0 XT-PIC cascade
8: 1 0 IO-APIC-edge rtc
9: 0 0 IO-APIC-level acpi
14: 5062 5316 IO-APIC-edge ide0
15: 1 1 IO-APIC-edge ide1
16: 43464 43565 IO-APIC-level usb-uhci, usb-uhci, nvidia
17: 26180 26194 IO-APIC-level Intel ICH5
18: 119342344 119704504 IO-APIC-level ide2, usb-uhci
19: 1682 2649 IO-APIC-level usb-uhci
21: 460 467 IO-APIC-level eth0
22: 576 571 IO-APIC-level SysKonnect SK-98xx
23: 18 15 IO-APIC-level ehci-hcd
NMI: 0 0
LOC: 104773 104781
ERR: 0
MIS: 6
Except ide2 is sharing it's interrupt with a usb controller. Doing
nothing gives:
20:08:28 up 19 min, 3 users, load average: 0.08, 0.06, 0.02
75 processes: 74 sleeping, 1 running, 0 zombie, 0 stopped
CPU0 states: 0.5% user 20.2% system 0.0% nice 0.0% iowait 78.2%
idle
CPU1 states: 0.5% user 17.0% system 0.0% nice 0.0% iowait 81.4%
idle
Mem: 515128k av, 187396k used, 327732k free, 0k shrd, 13336k
buff
45524k active, 118320k inactive
Swap: 787176k av, 0k used, 787176k free 90804k
cached
With your patch and in XP a have a nice nullish system load.
Greetings,
Jurgen
Jurgen Kramer wrote:
> BTW it seems that all ATA ports have their own interrupt:
>
> CPU0 CPU1
> 14: 5062 5316 IO-APIC-edge ide0
> 15: 1 1 IO-APIC-edge ide1
> 16: 43464 43565 IO-APIC-level usb-uhci, usb-uhci, nvidia
> 17: 26180 26194 IO-APIC-level Intel ICH5
> 18: 119342344 119704504 IO-APIC-level ide2, usb-uhci
The interrupt count is definitely high.
WRT the interrupt distribution through, the above is normal. irq 14 and
15 are the magic legacy IDE interrupts. Anything other than 14 and 15
are (usually) standard shareable PCI interrupts.
> 20:08:28 up 19 min, 3 users, load average: 0.08, 0.06, 0.02
> 75 processes: 74 sleeping, 1 running, 0 zombie, 0 stopped
> CPU0 states: 0.5% user 20.2% system 0.0% nice 0.0% iowait 78.2%
> idle
> CPU1 states: 0.5% user 17.0% system 0.0% nice 0.0% iowait 81.4%
> idle
> Mem: 515128k av, 187396k used, 327732k free, 0k shrd, 13336k
> buff
> 45524k active, 118320k inactive
> Swap: 787176k av, 0k used, 787176k free 90804k
> cached
>
> With your patch and in XP a have a nice nullish system load.
Very strange. My first guess would be that the drivers/ide driver
appears unfriendly to shared interrupts. In certain cases the ATA
protocol does not offer a single, easy "is this interrupt mine?" test;
the logic has to be implicitly worked into the driver code. However,
normally the drivers/ide driver knows what the heck it is doing, so this
is quite out of the ordinary.
Perhaps you can fiddle with BIOS settings to get ide2 onto an interrupt
all by itself, and see if the behavior improves.
Jeff