Re: [RFC PATCH] nvme-pci: adaptively poll completions on busy queues

> From: "Christoph Hellwig"<[email protected]>
> Date:  Tue, Jul 28, 2026, 12:44
> Subject:  Re: [RFC PATCH] nvme-pci: adaptively poll completions on busy queues
> To: "changfengnan"<[email protected]>
> Cc: <[email protected]>, "Keith Busch"<[email protected]>, "Jens Axboe"<[email protected]>, "Christoph Hellwig"<[email protected]>, "Sagi Grimberg"<[email protected]>, "Bart Van Assche"<[email protected]>, "Andy Shevchenko"<[email protected]>, "Thomas Gleixner"<[email protected]>, "Jun Zeng"<[email protected]>, "Gang Cao"<[email protected]>, "Jun I Jin"<[email protected]>, "Liang A Fang"<[email protected]>, "Yong Hu"<[email protected]>, <[email protected]>, "Guzebing"<[email protected]>
> On Tue, Jul 28, 2026 at 10:24:52AM +0800, changfengnan wrote:
> > The patch showed 50 confirmed throughput improvements, with a median gain of 25.2%
> > and a maximum gain of 63.0%. Only five cases showed confirmed regressions;
> 
> Can you drill down into the regression and figure out why they happen
> and if we can mitigate them?  It would be nice if we could find a way
> to avoid major regressions and enable the adaptive mode by default.

Of course, we’ll continue to investigate this issue to minimize performance
regressions. As for enabling it by default, it’s too early to say—we need
more testing to verify this, such as seeing how it performs on Gen3/Gen4
NVMe drives.

>