On Wed, Sep 15, 2021 at 02:11:41PM +0200, Paolo Bonzini wrote: > On 13/09/21 15:10, Stefan Hajnoczi wrote: > > On Wed, Sep 08, 2021 at 09:10:17AM -0400, Emanuele Giuseppe Esposito wrote: > > > Currently, block layer APIs like block-backend.h contain a mix of > > > functions that are either running in the main loop and under the > > > BQL, or are thread-safe functions and run in iothreads performing I/O. > > > The functions running under BQL also take care of modifying the > > > block graph, by using drain and/or aio_context_acquire/release. > > > This makes it very confusing to understand where each function > > > runs, and what assumptions it provided with regards to thread > > > safety. > > > > > > We call the functions running under BQL "graph API", and > > > distinguish them from the thread-safe "I/O API". > > > > Maybe "BQL" is clearer than "graph" because not all functions classified > > as "graph" need to traverse/modify the graph. > > Bikeshedding, I like it! :) > > ... on the other hand, qemu-storage-daemon does not have a BQL (see patch > 1); "graph API" functions run from the main (monitor) thread. > > The characteristic of the "graph API" is that they affect global state, so > another possibility could be "global state API". But is there any global > state apart from the BlockDriverState graph and the associated > BlockBackends?
I would be happy with that name too. Stefan
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