linux-kernel - Re: This is the fourth time I’ve tried to find what led to the regression of outgoing network speed and each time I find the merge commit 8c94ccc7cd691472461448f98e2372c75849406c

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Date: Tue, 6 Feb 2024 21:12:24 +0500
From: Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>
To: Mathias Nyman <mathias.nyman@...ux.intel.com>
Cc: "Christian A. Ehrhardt" <lk@...e.de>, niklas.neronin@...ux.intel.com, 
	Linux List Kernel Mailing <linux-kernel@...r.kernel.org>, Greg KH <gregkh@...uxfoundation.org>, 
	linux-usb@...r.kernel.org
Subject: Re: This is the fourth time I’ve tried to find what led to the regression of outgoing network speed and each time I find the merge commit 8c94ccc7cd691472461448f98e2372c75849406c

On Tue, Feb 6, 2024 at 4:24 PM Mathias Nyman
<mathias.nyman@...ux.intel.com> wrote:
>
>
> This seems odd, not sure how this usb host change would impact your network speed.
>
> Could you try reverting that patch from 6.8-rc1 and see if it helps?
>
> There are some other patches on top of it that needs to be reverted first.
> These should be enough:
>
> 36b24ebf9a04 xhci: minor coding style cleanup in 'xhci_try_enable_msi()
> 9831960df237 xhci: rework 'xhci_try_enable_msi()' MSI and MSI-X setup code
> dfbf4441f2d3 xhci: change 'msix_count' to encompass MSI or MSI-X vectors
> a795f708b284 xhci: refactor static MSI function
> 74554e9c2276 xhci: refactor static MSI-X function
> f977f4c9301c xhci: add handler for only one interrupt line

I confirm after reverting all listed commits and 57e153dfd0e7
performance of the network returned to theoretical maximum.

> That patch changes how we request MSI/MSI-X interrupt(s) for xhci.
>
> Is there any change is /proc/interrupts between a good and bad case?
> Such as xhci_hcd using MSI-X instead of MSI, or eth0 and xhci_hcd
> interrupting on the same CPU?

On the good kernel I have - 32 xhci_hcd, and bad only - 4.
In both scenarios using PCI-MSIX.
I attached both interrupt output as archives to this message.

[1] https://postimg.cc/zL2RYgYZ

-- 
Best Regards,
Mike Gavrilov.

Download attachment "interrupts-good.zip" of type "application/zip" (3009 bytes)

Download attachment "interrupts-bad.zip" of type "application/zip" (3097 bytes)