Re: INTMS/INTMC not being used in NVME interrupt handling
- Date: Wed, 16 May 2018 08:42:40 -0600
- From: Keith Busch <keith.busch@xxxxxxxxxxxxxxx>
- Subject: Re: INTMS/INTMC not being used in NVME interrupt handling
On Wed, May 16, 2018 at 12:35:15PM +0000, Bharat Kumar Gogada wrote:
> As per NVME specification:
> 18.104.22.168 Host Software Interrupt Handling
> It is recommended that host software utilize the Interrupt Mask Set and Interrupt Mask Clear (INTMS/INTMC)
> registers to efficiently handle interrupts when configured to use pin based or MSI messages.
> In kernel 4.14, drivers/nvme/host/pci.c function nvme_isr
> doesn't use these registers.
> Any reason why these registers are not used in nvme interrupt handler ?
I think you've answered your own question: we process completions in the
interrupt context. The interrupt is already masked at the CPU level in
this context, so there should be no reason to mask them at the device
> Why NVMe driver is not using any bottom half and processing all completion queues
> in interrupt handler ?