Revert readv optimization in virtio-net device #4839
Closed
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
The changes introduced in IoVecBufferMut that allowed implementing readv support for virtio-net regressed the performance of vsock device. This is because now, when we create IoVecBufferMut objects we do a bunch (1 memfd_create and 3 mmap) of system calls. virtio-net device avoids the performance issue because it creates a single IoVecBufferMut and re-uses it, whereas vsock is creating a new IoVecBufferMut object for every packet it receives. We have a fix for this, which essentially creates a single IoVecBufferMut that reuses for all the incoming vsock packets during a connection. The problem with the fix is that it makes unit-tests really unhappy and we need a significant amount of work to fix them. So, revert the PR to have main in a clean state. We will fix the vsock issues out-of-band and re-open the PR. This reverts commits: - bc0ba43 - 667aba4 - 5d718d4 - 14e6e33 - 1e4c632 from PR firecracker-microvm#4799 Signed-off-by: Babis Chalios <bchalios@amazon.es>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
The changes introduced in IoVecBufferMut that allowed implementing readv support for virtio-net regressed the performance of vsock device. This is because now, when we create IoVecBufferMut objects we do a bunch (1 memfd_create and 3 mmap) of system calls. virtio-net device avoids the performance issue because it creates a single IoVecBufferMut and re-uses it, whereas vsock is creating a new IoVecBufferMut object for every packet it receives.
We have a fix for this, which essentially creates a single IoVecBufferMut that reuses for all the incoming vsock packets during a connection. The problem with the fix is that it makes unit-tests really unhappy and we need a significant amount of work to fix them.
So, revert the PR to have main in a clean state. We will fix the vsock issues out-of-band and re-open the PR.
This reverts commits:
from PR #4799
Changes
...
Reason
...
License Acceptance
By submitting this pull request, I confirm that my contribution is made under
the terms of the Apache 2.0 license. For more information on following Developer
Certificate of Origin and signing off your commits, please check
CONTRIBUTING.md.PR Checklist
PR.
CHANGELOG.md.TODOs link to an issue.contribution quality standards.
rust-vmm.