lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Thu, 17 Sep 2020 14:31:07 -0400
From:   Nitesh Narayan Lal <>
To:     Jesse Brandeburg <>
        "Luis Claudio R. Goncalves" <>
Subject: Re: [RFC][Patch v1 2/3] i40e: limit msix vectors based on
 housekeeping CPUs

On 9/17/20 2:23 PM, Jesse Brandeburg wrote:
> Nitesh Narayan Lal wrote:
>> In a realtime environment, it is essential to isolate unwanted IRQs from
>> isolated CPUs to prevent latency overheads. Creating MSIX vectors only
>> based on the online CPUs could lead to a potential issue on an RT setup
>> that has several isolated CPUs but a very few housekeeping CPUs. This is
>> because in these kinds of setups an attempt to move the IRQs to the
>> limited housekeeping CPUs from isolated CPUs might fail due to the per
>> CPU vector limit. This could eventually result in latency spikes because
>> of the IRQ threads that we fail to move from isolated CPUs.
>> This patch prevents i40e to add vectors only based on available
>> housekeeping CPUs by using num_housekeeping_cpus().
>> Signed-off-by: Nitesh Narayan Lal <>
> The driver changes are straightforward, but this isn't the only driver
> with this issue, right?

Indeed, I was hoping to modify them over the time with some testing.

>   I'm sure ixgbe and ice both have this problem
> too, you should fix them as well, at a minimum, and probably other
> vendors drivers:

Sure, I can atleast include ixgbe and ice in the next posting if that makes
The reason I skipped them is that I was not very sure about the right way to
test these changes.

> $ rg -c --stats num_online_cpus drivers/net/ethernet
> ...
> 50 files contained matches
> for this patch i40e
> Acked-by: Jesse Brandeburg <>

Download attachment "signature.asc" of type "application/pgp-signature" (834 bytes)

Powered by blists - more mailing lists