Re: [EXTERNAL] Re: [PATCH] net :mana : Add per-cpu stats for MANA device

[Shradha Gupta]

Hi all,
I have a newer version of this patch with netlink implementation ready, to support the usecase of per-cpu stats for RSS handling and imbalance investigations. Please let me know if we can proceed with that.

Thanks and regards,
Shradha.

On Thu, Mar 14, 2024 at 08:01:24PM +0000, Alireza Dabagh wrote:
> Per processor network stats have been supported on netvsc and Mellanox NICs for years. They are also supported on Windows.
> 
> I routinely use these stats to rule in/out the issues with RSS imbalance due to either NIC not handling RSS correctly, incorrect MSI-X affinity, or not having enough entropy in flows. 
> 
> And yes, I perfectly understand that there are cases that packets received on processor x are processed (in tcp/ip stack) on processor y. But in many cases, there is a correlation between individual processor utilization and the processor where these packets are received on by the NIC.
> 
> -thanks, ali
> (some suggested that I do mention on this thread that I am one of the original inventors of RSS. So there you have it. Personally I don't think that telling people "I invented the damn thing and I know what I am talking about" is the right way to handle this.) 
> -----Original Message-----
> From: Jakub Kicinski <kuba@xxxxxxxxxx> 
> Sent: Thursday, March 14, 2024 12:05 PM
> To: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> Cc: Shradha Gupta <shradhagupta@xxxxxxxxxxxxxxxxxxx>; Shradha Gupta <shradhagupta@xxxxxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; linux-hyperv@xxxxxxxxxxxxxxx; linux-rdma@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; Eric Dumazet <edumazet@xxxxxxxxxx>; Paolo Abeni <pabeni@xxxxxxxxxx>; Ajay Sharma <sharmaajay@xxxxxxxxxxxxx>; Leon Romanovsky <leon@xxxxxxxxxx>; Thomas Gleixner <tglx@xxxxxxxxxxxxx>; Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>; KY Srinivasan <kys@xxxxxxxxxxxxx>; Wei Liu <wei.liu@xxxxxxxxxx>; Dexuan Cui <decui@xxxxxxxxxxxxx>; Long Li <longli@xxxxxxxxxxxxx>; Michael Kelley <mikelley@xxxxxxxxxxxxx>; Alireza Dabagh <alid@xxxxxxxxxxxxx>; Paul Rosswurm <paulros@xxxxxxxxxxxxx>
> Subject: [EXTERNAL] Re: [PATCH] net :mana : Add per-cpu stats for MANA device
> 
> On Thu, 14 Mar 2024 18:54:31 +0000 Haiyang Zhang wrote:
> > We understand irqbalance may be a "bad idea", and recommended some 
> > customers to disable it when having problems with it... But it's still 
> > enabled by default, and we cannot let all distro vendors and custom 
> > image makers to disable the irqbalance. So, our host- networking team 
> > is eager to have per-CPU stats for analyzing CPU usage related to 
> > irqbalance or other issues.
> 
> You need a use case to get the stats upstream.
> "CPU usage related to irqbalance or other issues" is both too vague, and irqbalance is a user space problem.