Messages in this thread | | | Date | Mon, 15 Jan 2007 20:23:30 +0530 | From | Vaidyanathan Srinivasan <> | Subject | Re: prioritize PCI traffic ? |
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Soeren Sonnenburg wrote: > On Mon, 2007-01-15 at 19:23 +0530, Vaidyanathan Srinivasan wrote: >> Soeren Sonnenburg wrote: >>> Dear all, >>> >>> is it possible to explicitly tell the kernel to prioritize PCI traffic >>> for a number of cards in pci slots x,y,z ? >>> >>> I am asking as severe ide traffic causes lost frames when watching TV >>> using 2 DVB cards + vdr... This is simply due to the fact that the PCI >>> bus is saturated... >> How do you know that the bus is saturated? > > I simply dd if=/dev/sd? of=/dev/null from four brand new sata-harddisks. > >> Are you streaming data to/from the ide hard disks/CDROM? > > yes. > >> Do you have DMAs 'ON' for the hard disks? > > yes.
Good.
>> Is everything just fine if there are no IDE traffic? > > yes.
Good.
>> Are you running 2.6 kernel with preempt 'ON'? > > no: CONFIG_PREEMPT_NONE=y >
Try CONFIG_PREEMPT=y it may help. It made the system more responsive for me.
>> Are all hardware on the same IRQ line? (shared interrupts) > > no: libata devices are on IRQ 16 and DVB devices on IRQ 20
Watch the interrupt count (/proc/interrupts) and interrupt rate, that may give some clue on what is happening on the PCI bus.
> >>> So, is any prioritizing of the PCI bus possible ? >> The drivers + application indirectly can control priority on the >> bus. Just reduce the priority of the application that uses IDE and >> see if adjusting nice values of applications can change the scenario. > > That unfortunately did not help... no change...
33Mhz 32-bit PCI bus on typical PC can do around 100MB/sec... watch your individual disk transfer rates and data rate to each DVB. dd from 4 new SATA drive will probably fillup the bus. However, depending on your motherboard, the integrated SATA controllers may be on a different PCI bus than the one for the slots.
You can watch the lspci output to determine which bus the devices are located.
--Vaidy
> > Soeren > -- > Sometimes, there's a moment as you're waking, when you become aware of > the real world around you, but you're still dreaming. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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