Fix submission queue overflow on large blob writes #520
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pereman2
requested changes
Dec 20, 2024
| @@ -49,7 +50,7 @@ struct InnerLinuxIO { | |||
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| impl LinuxIO { | |||
| pub fn new() -> Result<Self> { | |||
| let ring = io_uring::IoUring::new(MAX_IOVECS as u32)?; | |||
| let ring = io_uring::IoUring::new(SUBQ_ENTRYS)?; | |||
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spelling nit
Suggested change
| let ring = io_uring::IoUring::new(SUBQ_ENTRYS)?; | |
| let ring = io_uring::IoUring::new(SUBQ_ENTRIES)?; |
Comment on lines
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| match res { | ||
| Ok(_) => break, | ||
| Err(_) => { | ||
| let _ = self.wait_for_completion(); | ||
| } |
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I'm not a fan of this, we are ignoring the error and we are waiting for completion for everything. This feels kinda wrong honestly because that would mean that if you try to write a big blob it will for the connection to wait instead of returning control to it as we would expect from limbo.
In my opinion submit_entry should return submission is full and therefore there should be a state machine in write path that can resume long writes on next iteration.
cc: @penberg
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#406
From everything I have read, just adjusting the sub queue entries size should be fine... Obviously spin-locking on an entry to be processed is not exactly ideal here but with the entries sized increased it seems like that isn't a likely situation. More than a few examples I found are creating a ring with >= 256.
All the other possible improvements I have read about don't really apply to this use-case (batch submissions being the primary one I have seen)
Probably should add tests with large blob inserts, right now the only tests that are doing inserts is in
shelltests.pyEDIT: Currently exploring the possible realistic solutions discussed on discord.