[dm-devel] Latest dm-userspace kernel code

[Dan Smith]

FT> I'm talking about removing dmu_request->deps (dependent request
FT> feature). Seems that you are talking about DMU_FLAG_COPY_FIRST
FT> feature (it's ok for me).

Ah, I see.  Sorry for the confusion :)

FT> My point is that the dependent request feature can be done in user
FT> space easily. If a user-space program gets a request trying to
FT> perform I/Os in the same block that an outgoing request with
FT> DMU_FLAG_COPY_FIRST are performing I/Os too, it waits for the I/O
FT> completion and then submit the new request to kernel space.

Yes, I think this is a good idea.  I will put it on my list of things
to do next week.

FT> I think that AIO is essential for the metadata issue even with
FT> DMU_FLAG_COPY_FIRST and dependent request features, though the
FT> DMU_FLAG_COPY_FIRST feature is important for writing a newly
FT> allocated cow block.

Yes, I fully intend to use AIO for metadata flushing eventually.

-- 
Dan Smith
IBM Linux Technology Center
Open Hypervisor Team
email: danms at us.ibm.com
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