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Re: [Qemu-devel] [Qemu-discuss] IRQ per CPU
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From: |
Dongli Zhang |
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Subject: |
Re: [Qemu-devel] [Qemu-discuss] IRQ per CPU |
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Date: |
Thu, 5 Jul 2018 15:16:44 +0800 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 |
On 07/05/2018 12:12 PM, Probir Roy wrote:
>> Does 'per CPU basis' indicates irq per cpu, or irq per device queue?
>
> IRQ per CPU core, meaning that IRQ will be raised at and served by
> that CPU. Does IRQ per queue mean the same thing?
>
About 'IRQ per queue', the device may create multiple queue in the OS driver.
The number of queues are always proportional to the number of CPU core/thread
(although this is also always configurable by OS driver).
Usually the per-queue irq/vector is bound to each CPU. As the number of
queue/irq is always the same as the number of CPU, it is sort of 'per CPU
basis', as each CPU will be serving irq for its own queue.
Dongli Zhang