-
Notifications
You must be signed in to change notification settings - Fork 1.7k
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
Remove some dead ARC code. #14340
Merged
Merged
Remove some dead ARC code. #14340
Changes from all commits
Commits
File filter
Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
There are no files selected for viewing
This file contains 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
This file contains 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
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Outdated suggestions cannot be applied.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.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
What do you think about making some or all of these VERIFYs to make sure that the assumptions here are valid in non-debug builds?
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
This is a very hot single-threaded piece of code, limiting system performance on some workloads. I do not want VERIFY() impossible here without a good reason. Any particular reason you think this may work different for debug and non-debug builds?
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
If you're convinced that this can't happen then no need to be defensive. My concern was that if we find that the
b_buf
is not being destroyed because of some missed code path, then we end up with a memory leak which would be hard to track down. Doing a simpleVERIFY3P(hdr->b_l1hdr.b_buf, ==, NULL)
would allow for a quick diagnosis on non-debug bits. If you've stressed tested this significantly then I would agree that leaving these off makes sense if they can't happen.There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
I've added the assertions to protect from some logical bugs. Since it didn't fire yet on any tests, I tend to think it won't, and the assertions will just make sure that whoever modify the code in future will have a guard rail.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
And it likely won't leak any way. It will get evicted to ghost state with the buffer, and on eviction from there arc_hdr_destroy() frees any possible remaining buffers. I thought to remove it also, but appeared it is actually used when arc_buf_destroy() calls remove_reference() for anonymous header without getting the hash lock.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Ok. The arc behaves very differently in non-debug builds so some of the inherit race conditions may not show up there. I will trust that you're confident enough in the change.