[PATCHv2 4/4] nvme-pci: Use PCI to handle IRQ reduce and retry

Ming Lei
2019-01-04T02:41:18Z

On Thu, Jan 03, 2019@03:50:33PM -0700, Keith Busch wrote:
> Restore error handling for vector allocation back to the PCI core.
>
> Signed-off-by: Keith Busch <keith.busch at intel.com>
> ---
> drivers/nvme/host/pci.c | 77 ++++++++++++++-----------------------------------
> 1 file changed, 21 insertions(+), 56 deletions(-)
>
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 1481bb6d9c42..f3ef09a8e8f9 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -2059,37 +2059,43 @@ static int nvme_setup_host_mem(struct nvme_dev *dev)
> return ret;
> }
>
> -static void nvme_calc_io_queues(struct nvme_dev *dev, unsigned int irq_queues)
> +static void nvme_calc_io_queues(struct irq_affinity *affd, unsigned int nvecs)
> {
> + struct nvme_dev *dev = affd->priv;
> unsigned int this_w_queues = write_queues;
>
> /*
> * Setup read/write queue split
> */
> - if (irq_queues == 1) {
> + if (nvecs == 1) {

The above line can be 'nvecs <= 2', cause when nvecs is 2, one is for
admin queue, another can be for DEFAULT.

> dev->io_queues[HCTX_TYPE_DEFAULT] = 1;
> dev->io_queues[HCTX_TYPE_READ] = 0;
> - return;
> + goto set_sets;
> }
>
> /*
> * If 'write_queues' is set, ensure it leaves room for at least
> * one read queue
> */
> - if (this_w_queues >= irq_queues)
> - this_w_queues = irq_queues - 1;
> + if (this_w_queues >= nvecs - 1)
> + this_w_queues = nvecs - 1;

If we want to leave room for one read queue, 'this_w_queues' should be
set as 'nvecs - 2' given nvecs covers admin queue.

>
> /*
> * If 'write_queues' is set to zero, reads and writes will share
> * a queue set.
> */
> if (!this_w_queues) {
> - dev->io_queues[HCTX_TYPE_DEFAULT] = irq_queues;
> + dev->io_queues[HCTX_TYPE_DEFAULT] = nvecs - 1;
> dev->io_queues[HCTX_TYPE_READ] = 0;
> } else {
> dev->io_queues[HCTX_TYPE_DEFAULT] = this_w_queues;
> - dev->io_queues[HCTX_TYPE_READ] = irq_queues - this_w_queues;
> + dev->io_queues[HCTX_TYPE_READ] = nvecs - this_w_queues - 1;
> }

In above change, looks you starts to consider admin queue vector, which
is obvious one issue in current code.

So I'd suggest to fix nvme_calc_io_queues() in one standalone patch,
just what I posted, given this patch doesn't do "Restore error
handling for vector allocation back to the PCI core" only.

http://lists.infradead.org/pipermail/linux-nvme/2018-December/021879.html

Thanks,
Ming