* ICH5 SATA causes high interrupt/system load? @ 2003-07-01 19:24 Jurgen Kramer 2003-07-01 20:41 ` Jeff Garzik 0 siblings, 1 reply; 4+ messages in thread From: Jurgen Kramer @ 2003-07-01 19:24 UTC (permalink / raw) To: linux-kernel 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 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: ICH5 SATA causes high interrupt/system load? 2003-07-01 19:24 ICH5 SATA causes high interrupt/system load? Jurgen Kramer @ 2003-07-01 20:41 ` Jeff Garzik 2003-07-02 18:10 ` Jurgen Kramer 0 siblings, 1 reply; 4+ messages in thread From: Jeff Garzik @ 2003-07-01 20:41 UTC (permalink / raw) To: Jurgen Kramer; +Cc: linux-kernel 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 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: ICH5 SATA causes high interrupt/system load? 2003-07-01 20:41 ` Jeff Garzik @ 2003-07-02 18:10 ` Jurgen Kramer 2003-07-02 23:07 ` Jeff Garzik 0 siblings, 1 reply; 4+ messages in thread From: Jurgen Kramer @ 2003-07-02 18:10 UTC (permalink / raw) To: Jeff Garzik; +Cc: linux-kernel 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 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: ICH5 SATA causes high interrupt/system load? 2003-07-02 18:10 ` Jurgen Kramer @ 2003-07-02 23:07 ` Jeff Garzik 0 siblings, 0 replies; 4+ messages in thread From: Jeff Garzik @ 2003-07-02 23:07 UTC (permalink / raw) To: Jurgen Kramer; +Cc: linux-kernel 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 ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2003-07-02 22:55 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2003-07-01 19:24 ICH5 SATA causes high interrupt/system load? Jurgen Kramer 2003-07-01 20:41 ` Jeff Garzik 2003-07-02 18:10 ` Jurgen Kramer 2003-07-02 23:07 ` Jeff Garzik
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