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Virtio-net: raise interrupt for TX queue used descriptors #1436

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sandreim opened this issue Nov 26, 2019 · 1 comment
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Virtio-net: raise interrupt for TX queue used descriptors #1436

sandreim opened this issue Nov 26, 2019 · 1 comment
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Priority: High Indicates than an issue or pull request should be resolved ahead of issues or pull requests labelled Type: Bug Indicates an unexpected problem or unintended behavior

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sandreim commented Nov 26, 2019 •
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This is a regression dating back to this PR: #413.

If the TX queue becomes full the guest would not be able to enqueue any TX packets until an RX from the tap device will raise the interrupt and the guest will inspect both RX/TX queue status.
The issue impacts the workloads where the TX:RX ratio is highly skewed towards TX, for example sending large bursts of traffic without doing much RX.

Before merging a fix benchmarking is needed to understand the performance implications of raising additional irqs.

TODO:

  • Implement irq raising for used descriptors (TX)
  • Performance benchmark
  • Integration test
@sandreim sandreim added Type: Bug Indicates an unexpected problem or unintended behavior Feature: IO Virtualization Priority: High Indicates than an issue or pull request should be resolved ahead of issues or pull requests labelled labels Nov 26, 2019
@sandreim sandreim changed the title Virtio-net: raise interrupt for used descriptors on tx queue Virtio-net: raise interrupt for TX queue used descriptors Nov 26, 2019
@sandreim sandreim self-assigned this Nov 26, 2019
sandreim added a commit to sandreim/firecracker that referenced this issue Dec 3, 2019
@sandreim
Raise interrupt for used descriptors on tx queue.
cc82e7c 
Add a unit test for this regression: firecracker-microvm#1436.

Signed-off-by: Andrei Sandu <[email protected]>
@sandreim sandreim mentioned this issue Dec 3, 2019
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sandreim added a commit to sandreim/firecracker that referenced this issue Dec 4, 2019
@sandreim
Raise interrupt for used descriptors on tx queue.
7fa4747 
Add a unit test for this regression: firecracker-microvm#1436.

Signed-off-by: Andrei Sandu <[email protected]>
sandreim added a commit that referenced this issue Dec 4, 2019
@sandreim
Raise interrupt for used descriptors on tx queue.
479a1be 
Add a unit test for this regression: #1436.

Signed-off-by: Andrei Sandu <[email protected]>
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sandreim commented Dec 4, 2019

Fixed in PR #1444

@sandreim sandreim closed this as completed Dec 4, 2019
iulianbarbu pushed a commit to iulianbarbu/firecracker that referenced this issue Mar 18, 2020
@sandreim
Raise interrupt for used descriptors on tx queue.
e0e1bc3 
Add a unit test for this regression: firecracker-microvm#1436.

Signed-off-by: Andrei Sandu <[email protected]>
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