Subject: Re: [Patch v3] net: mana: Batch ringing RX queue doorbell on receiving packets
On Sun, 2023-07-02 at 20:18 +0000, Long Li wrote:
> > > Subject: Re: [Patch v3] net: mana: Batch ringing RX > > > queue doorbell on receiving packets > > > > > > On Fri, 30 Jun 2023 20:42:28 +0000 Long Li wrote: > > > > > > > > > > > > > > > 5.15 and kernel 6.1. (those > > > > > > > > > > > > > > > kernels are longterm) They need > > > > > > > > > > > > > > > this fix to achieve the > > > > > > > > > > > > > > > performance target. > > > > > > > > > > > > > > > > > > > > > > Why can't they be upgraded to get that > > > > > > > > > > > performance target, and all the other > > > > > > > > > > > goodness that those kernels have? We > > > > > > > > > > > don't normally backport new features, > > > > > > > > > > > right? > > > > > > > > > > > > > > I think this should be considered as a fix, not > > > > > > > a new feature. > > > > > > > > > > > > > > MANA is designed to be 200GB full duplex at the > > > > > > > start. Due to lack of hardware testing > > > > > > > capability at early stage of the project, we > > > > > > > could only test 100GB for the Linux driver. When > > > > > > > hardware is fully capable of reaching designed > > > > > > > spec, this bug in the Linux driver shows up. > > > > > > That part we understand. > > > > > > If I were you I'd try to convince Greg and Paolo that > > > the change is small and significant for user experience. > > > And answer Greg's question why upgrading the kernel past > > > 6.1 is a challenge in your environment.
I was under the impression that this patch was considered to be a feature, not a bug fix. I was trying to justify that the "Fixes:" tag was needed.
I apologize for misunderstanding this.
Without this fix, it's not possible to run a typical workload designed for 200Gb physical link speed.
We see a large number of customers and Linux distributions committed on 5.15 and 6.1 kernels. They planned the product cycles and certification processes around these longterm kernel versions. It's difficult for them to upgrade to newer kernel versions.
I think there are some misunderstanding WRT distros and stable kernels. (Commercial) distros will backport the patch as needed, regardless such patch landing in the 5.15 upstream tree or not. Individual users running their own vanilla 5.15 kernel can't expect performance improvement landing there.
All in all I feel undecided. I would endorse this change going trough net-next (without the stable tag). I would feel less torn with this change targeting -net without the stable tag. Targeting -net with the stable tag sounds a bit too much to me.
Cheers, Paolo
I'm sending this patch to net-next without stable tag.
Thanks,
Long