BCM5719(tg3) use multiple MSI with RSS
Subsystems (2)
Hi all
Currently, I need to enable multiple MSI on BCM5719 network card. But I look in to the spec of 5719 from Broadcom, it seems that RSS just enable with MSI-X, so I'm not sure if multiple MSI can use RSS.
And if multiple MSI can't use RSS, how other usage of the interrupts allocated from the system? Can they be used to improve the performance of the network?
Thanks
Mike
Quoted 7 lines · Mike Qiu
Hi all
Currently, I need to enable multiple MSI on BCM5719 network card. But I look in to the spec of 5719 from Broadcom, it seems that RSS just enable with MSI-X, so I'm not sure if multiple MSI can use RSS.
MSI can only support one IRQ source and cannot support RSS.
Quoted 10 lines · Michael Chan
Quoted 7 lines · Mike Qiu
Hi all
Currently, I need to enable multiple MSI on BCM5719 network card. But I look in to the spec of 5719 from Broadcom, it seems that RSS just enable with MSI-X, so I'm not sure if multiple MSI can use RSS.
MSI can only support one IRQ source and cannot support RSS.
It is possible for an MSI capability to have multiple MSIs, but they will use the same address and consecutive data values.
On x86, if you can find a large enough block of free IRQs on an IOAPIC, it is possible to implement RSS this way. Linux supports this on systems with an x2apic.
Now, maybe tg3 hardware doesn't support this (and really, why bother when there is MSI-X?) but the option does exist.
Ben.
Signature · 3 lines
Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.
Quoted 15 lines · Ben Hutchings
Quoted 10 lines · Michael Chan
Quoted 7 lines · Mike Qiu
Hi all
Currently, I need to enable multiple MSI on BCM5719 network card. But I look in to the spec of 5719 from Broadcom, it seems that RSS just enable with MSI-X, so I'm not sure if multiple MSI can use RSS.
MSI can only support one IRQ source and cannot support RSS.
It is possible for an MSI capability to have multiple MSIs, but they will use the same address and consecutive data values.
Quoted 6 lines
On x86, if you can find a large enough block of free IRQs on an IOAPIC, it is possible to implement RSS this way. Linux supports this on systems with an x2apic.
Now, maybe tg3 hardware doesn't support this (and really, why bother when there is MSI-X?) but the option does exist.
Yes, tg3 hardware (may be all Broadcom hardware) can only use MSI as a replacement for INTA.
Quoted 14 lines · Michael Chan
Quoted 13 lines · Ben Hutchings
Quoted 9 lines · Michael Chan
Quoted 7 lines · Mike Qiu
Hi all
Currently, I need to enable multiple MSI on BCM5719 network card. But I look in to the spec of 5719 from Broadcom, it seems that RSS just enable with MSI-X, so I'm not sure if multiple MSI can use RSS.
MSI can only support one IRQ source and cannot support RSS.
It is possible for an MSI capability to have multiple MSIs, but they will use the same address and consecutive data values.
Quoted 8 lines
Quoted 6 lines
On x86, if you can find a large enough block of free IRQs on an IOAPIC, it is possible to implement RSS this way. Linux supports this on systems with an x2apic.
Now, maybe tg3 hardware doesn't support this (and really, why bother when there is MSI-X?) but the option does exist.
Yes, tg3 hardware (may be all Broadcom hardware) can only use MSI as a replacement for INTA.
That you mean, it can't use multiple MSI for RSS ?
Quoted 1 line
Quoted 4 lines · Ben Hutchings
Quoted 3 lines · Michael Chan
Quoted 2 lines · Mike Qiu
Hi all
Quoted 8 lines
Quoted 6 lines
Quoted 5 lines
Currently, I need to enable multiple MSI on BCM5719 network card. But I look in to the spec of 5719 from Broadcom, it seems that RSS just enable with MSI-X, so I'm not sure if multiple MSI can use RSS.
MSI can only support one IRQ source and cannot support RSS.
It is possible for an MSI capability to have multiple MSIs, but they will use the same address and consecutive data values.
Yes, it should be this.
Quoted 3 lines
On x86, if you can find a large enough block of free IRQs on an IOAPIC, it is possible to implement RSS this way. Linux supports this on systems with an x2apic.
But, I see the tg3 spec, and it seems the RSS is just for MSI-X(and IOV). And I try to enable RSS use multiple MSI for 4 irqs, the system
alloc 4 consecutive irqs to tg3, and each one can be test pass using interrupt test. But the last 3 interrupts seems not to be triggered as "cat /proc/interrups" shows after the driver loaded. Only the first irq can be triggered for only sometimes. The network surely not work.
Quoted 2 lines
Now, maybe tg3 hardware doesn't support this (and really, why bother when there is MSI-X?) but the option does exist.
Actually, I try to enable the multiple MSI feature, and needs tg3 card to support this feature. For some old PCI device, it may only support multiple MSI
Thanks
Mike
Quoted 3 lines
Ben.