From: "Budiský Jakub" <ibudisky@fit.vutbr.cz>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: users@dpdk.org
Subject: Re: [dpdk-users] Interrupt mode, queues, own event loop
Date: Sat, 05 Sep 2020 23:21:06 +0200 [thread overview]
Message-ID: <db580197366c29c228e3b4b72b703b34@fit.vutbr.cz> (raw)
In-Reply-To: <20200904091827.59056b16@hermes.lan>
On 2020-09-04 18:18, Stephen Hemminger wrote:
> The per-queue interrupt functionality for PCI devices is built
> on top of MSI-X interrupts. The uio_pci_generic driver you are using
> does not support MSI-X.
>
> The way UIO driver works is to use the legacy INTx functionality,
> and when an interrupt occurs the device driver in the kernel is called.
> For the uio_pci_generic driver this is mapped to the device file
> descriptor.
>
> For VFIO, you can have one interrupt per queue and it uses eventfd's
> to create a per-queue channel.
Hi,
thanks for the valuable info!
I've now switched to the `vfio` module even for testing and I can
confirm I get a set of separate eventfd file descriptors. I've
encountered a new issue though that appears like a bug to me.
Either one of the file descriptors (`--vfio-intr msix`, always the one
associated with the last queue, regardless of the initialization order)
or all of them (`--vfio-intr msi`) are available for reading just once
per application run. I cannot get any followup interrupts and I can
confirm by polling that there are new packets that have arrived.
With `--vfio-intr legacy` I get a same file descriptor for all my
workers but it is also only triggered once.
As far as I understand there is no clear flag for the MSI(-X) interrupts
and so I'm not sure what else to try. There is nothing of interest in
the application output (not even with `--log-level lib.eal:debug`).
Thanks again.
Best regards,
Jakub Budisky
next prev parent reply other threads:[~2020-09-05 21:21 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 10:24 Budiský Jakub
2020-09-04 16:18 ` Stephen Hemminger
2020-09-05 21:21 ` Budiský Jakub [this message]
2020-09-08 15:09 ` Budiský Jakub
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