alc(4): disable MSI-X by default on Killer cards #1185
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bsdimp
reviewed
Apr 19, 2024
sys/dev/alc/if_alc.c
Outdated
| /* | ||
| * Disable MSI-X by default on Killer devices, since this is | ||
| * reported by several users to not work well. | ||
| * */ |
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Thanks for the CC, this makes sense to me. Do we know off hand if other operating systems (e.g. Linux or OpenBSD) do this? |
Several users with alc(4)-based "Killer" Ethernet cards have reported issues with this driver not passing traffic, which are solved by disabling MSI-X using the provided tunable. To work around this issue, disable MSI-X by default on this card. This is done by having msix_disable default to 2, which means "auto-detect". The user can still override this to either 0 or 1 as desired. Since these are slow (1Gbps) Ethernet ICs used in low-end systems, it's unlikely this will cause any practical performance issues; on the other hand, the card not working by default likely causes issues for many new FreeBSD users who find their network port doesn't work and have no idea why. PR: 230807 MFC after: 1 week
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on Linux the bug isn't present, but i spent several hours comparing their driver (alx) to ours and couldn't work out what they're doing differently. i did mail the listed maintainer of the Linux driver to ask for documentation on the chip (Qualcomm is not very forthcoming with this) but no luck. NetBSD from what i remember doesn't support MSI-X on this card. i'm not sure what OpenBSD does. i've fixed the comment typo. |
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Seems ready. Last call ... |
freebsd-git
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Apr 23, 2024
Several users with alc(4)-based "Killer" Ethernet cards have reported issues with this driver not passing traffic, which are solved by disabling MSI-X using the provided tunable. To work around this issue, disable MSI-X by default on this card. This is done by having msix_disable default to 2, which means "auto-detect". The user can still override this to either 0 or 1 as desired. Since these are slow (1Gbps) Ethernet ICs used in low-end systems, it's unlikely this will cause any practical performance issues; on the other hand, the card not working by default likely causes issues for many new FreeBSD users who find their network port doesn't work and have no idea why. PR: 230807 MFC after: 1 week Reviewed by: imp Pull Request: #1185
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merged |
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Several users with alc(4)-based "Killer" Ethernet cards have reported issues with this driver not passing traffic, which are solved by disabling MSI-X using the provided tunable.
To work around this issue, disable MSI-X by default on this card.
This is done by having msix_disable default to 2, which means "auto-detect". The user can still override this to either 0 or 1 as desired.
Since these are slow (1Gbps) Ethernet ICs used in low-end systems, it's unlikely this will cause any practical performance issues; on the other hand, the card not working by default likely causes issues for many new FreeBSD users who find their network port doesn't work and have no idea why.
PR: 230807
MFC after: 1 week
cc @emaste as you seem interested in user onboarding issues