Re: [PATCH v2] nvme-multipath: introduce service-time iopolicy

[Guixin Liu <kanie@linux.alibaba.com>]

在 2024/11/7 14:39, Christoph Hellwig 写道:
> On Thu, Nov 07, 2024 at 02:32:49PM +0800, Guixin Liu wrote:
>> The service-time policy can dispatch I/O to the path with the lowest
>> total amount of currently processed I/O, ensuring that new I/O can be
>> sent to less-loaded paths when some paths are overloaded, thereby
>> achieving lower latency.
> What is the exact use case for this?  The commit log is unfortunately
> very sparse.

In scenarios with varying random I/O sizes, the different I/O sizes 
being processed on

each path can lead to slower processing and higher latency on paths 
under heavy load. By

distributing the I/O to other paths with lighter loads, the I/O can be 
processed more

quickly.

Sorry for the sparse commit log, I will send a v3 to expain detaily.

>   All these little policies add up, and we have absolutely
> no documentation on them :(

I'm glad to add a document to introduce all these nvme-multipath polices 
within v3 patchset.

Best Regards,

Guixin Liu