linux-kernel - Re: [PATCH] PCI/LINK: Account for BW notification in vector calculation

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Date:   Mon, 22 Apr 2019 19:05:57 -0500
From:   Alex G <mr.nuke.me@...il.com>
To:     Alex Williamson <alex.williamson@...hat.com>, bhelgaas@...gle.com,
        helgaas@...nel.org, linux-pci@...r.kernel.org
Cc:     austin_bolen@...l.com, alex_gagniuc@...lteam.com,
        keith.busch@...el.com, Shyam_Iyer@...l.com, lukas@...ner.de,
        okaya@...nel.org, torvalds@...ux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI/LINK: Account for BW notification in vector
 calculation

On 4/22/19 5:43 PM, Alex Williamson wrote:
> [  329.725607] vfio-pci 0000:07:00.0: 32.000 Gb/s available PCIe bandwidth,
> limited by 2.5 GT/s x16 link at 0000:00:02.0 (capable of 64.000 Gb/s with 5
> GT/s x16 link)
> [  708.151488] vfio-pci 0000:07:00.0: 32.000 Gb/s available PCIe bandwidth,
> limited by 2.5 GT/s x16 link at 0000:00:02.0 (capable of 64.000 Gb/s with 5
> GT/s x16 link)
> [  718.262959] vfio-pci 0000:07:00.0: 32.000 Gb/s available PCIe bandwidth,
> limited by 2.5 GT/s x16 link at 0000:00:02.0 (capable of 64.000 Gb/s with 5
> GT/s x16 link)
> [ 1138.124932] vfio-pci 0000:07:00.0: 32.000 Gb/s available PCIe bandwidth,
> limited by 2.5 GT/s x16 link at 0000:00:02.0 (capable of 64.000 Gb/s with 5
> GT/s x16 link)
> 
> What is the value of this nagging?

Good! The bandwidth notification service is working as intended. If this 
bothers you, you can unbind the device from the bandwidth notification 
driver:

echo 0000:07:00.0:pcie010 |
sudo tee /sys/bus/pci_express/drivers/pcie_bw_notification/unbind



> diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
> index 7d04f9d087a6..1b330129089f 100644
> --- a/drivers/pci/pcie/portdrv_core.c
> +++ b/drivers/pci/pcie/portdrv_core.c
> @@ -55,7 +55,8 @@ static int pcie_message_numbers(struct pci_dev *dev, int mask,
>   	 * 7.8.2, 7.10.10, 7.31.2.
>   	 */
>   
> -	if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP)) {
> +	if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP |
> +		    PCIE_PORT_SERVICE_BWNOTIF)) {
>   		pcie_capability_read_word(dev, PCI_EXP_FLAGS, &reg16);
>   		*pme = (reg16 & PCI_EXP_FLAGS_IRQ) >> 9;
>   		nvec = *pme + 1;

Good catch!