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Two aio related questions

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Occasional Advisor

Two aio related questions


1. After an application has generated an aio to an AdvFS, does the UBC call back to say that the write is complete when it is in cache or when it is on disk?

2. After an aio is in cache, does the state of the transaction change in any way when getting sent to disk or does it just continue as an aio?

Erich Wimmer
Valued Contributor

Re: Two aio related questions

Assuming you mean the aio_write system call:

from the man page entry:
The aio_write function issues a write request and returns, even when the
data cannot be written immediately. If the request cannot be initiated, the
function returns with an error status. If an error condition occurs during
queuing, the function call returns without initiating the queue request.

See also aio_return(). If the data will be cached in ubc or written directly to disk depends on the open mode of the file and will be at aio_return. This doesn't mean it is already on disc, depending on the underlying I/O architecture.