[RFC PATCH 0/3] nvme-pci: dynamic interrupt moderation

[Fengnan]

Hi Keith:

I ran some quick tests using your patch on the PS1010 and SN861. 
For 4K random reads with QD=8, both drives showed a performance drop
of about 19%. 
With QD=64/128, there was an improvement of roughly 10–20%.

I think the reason is that the current logic still relies on the QD
depth to determine whether to switch, but a high QD doesn't necessarily
mean that using the poll mode will be more efficient.

As for DIM, I tried using it based on my V2 patch, but the result was
that I either had to add several new DIM functions to perform similar
checks, or I still ended up with a performance regression.

Here is detail data 
https://docs.google.com/spreadsheets/d/1VOR0xB5yk-z6IMwwRvp8R0yd4k_tMi_wI27Pl-dEQVg/edit?gid=789521759#gid=789521759

Based on the results, it doesn’t perform as well as my previous patch：
https://docs.google.com/spreadsheets/d/1rer4Nl5HHxSO-D3NrrHuHSfpR9s1kLhpLjzh7h7Mbmw/edit?gid=875909538#gid=875909538



在 2026/10/14 06:35, Keith Busch 写道:
> From: Keith Busch <kbusch at kernel.org>
> 
> Just adding another nvme hybrid interrupt and polling mechanism to the
> lists. There's some recent alternatives mentioned in the links below,
> but I'm trying one last time to leverage the DIM framework. Performance
> wise, this at least doesn't seem any worse than anything else proposed,
> though I've only been able to test on mid-level hardware so far.
> 
> This one here as some irq prep patches that help some when transitioning
> from irq to polling for MSI-x enabled NVMe completions. These should be
> generally applicable, so isn't necessarily tied to how it gets used in
> the last patch if someone else finds it useful too.
> 
> Links:
> 
>   [1] https://lore.kernel.org/linux-nvme/20261009050556.2817978-1-namjain@linux.microsoft.com/
> 
>   [2] https://lore.kernel.org/linux-nvme/20260818033846.53790-1-changfengnan@bytedance.com/
> 
> Keith Busch (3):
>   genirq: Add disable_irq_nowait()
>   PCI/MSI: Implement irq_mask_nowait() for MSI-X
>   nvme-pci: hybrid irq+polling
> 
>  drivers/irqchip/irq-msi-lib.c |   1 +
>  drivers/nvme/host/Kconfig     |   2 +
>  drivers/nvme/host/pci.c       | 624 ++++++++++++++++++++++++++++++++--
>  drivers/nvme/host/trace.c     |   1 +
>  drivers/nvme/host/trace.h     |  26 ++
>  drivers/pci/msi/irqdomain.c   |   6 +
>  drivers/pci/msi/msi.h         |   8 +-
>  include/linux/interrupt.h     |   1 +
>  include/linux/irq.h           |   4 +
>  kernel/irq/chip.c             |  31 ++
>  kernel/irq/internals.h        |   1 +
>  kernel/irq/manage.c           |  21 ++
>  12 files changed, 698 insertions(+), 28 deletions(-)
>