On Wed, Nov 29, 2023 at 04:26:20PM -0500, Stefan Hajnoczi wrote:
> The Big QEMU Lock (BQL) has many names and they are confusing. The
> actual QemuMutex variable is called qemu_global_mutex but it's commonly
> referred to as the BQL in discussions and some code comments. The
> locking APIs, however, are called qemu_mutex_lock_iothread() and
> qemu_mutex_unlock_iothread().
>
> The "iothread" name is historic and comes from when the main thread was
> split into into KVM vcpu threads and the "iothread" (now called the main
> loop thread). I have contributed to the confusion myself by introducing
> a separate --object iothread, a separate concept unrelated to the BQL.
>
> The "iothread" name is no longer appropriate for the BQL. Rename the
> locking APIs to:
> - void qemu_bql_lock(void)
> - void qemu_bql_unlock(void)
> - bool qemu_bql_locked(void)
>
> There are more APIs with "iothread" in their names. Subsequent patches
> will rename them. There are also comments and documentation that will be
> updated in later patches.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
Acked-by: Peter Xu <peterx@xxxxxxxxxx>
Two nickpicks:
- BQL contains "QEMU" as the 2nd character, so maybe easier to further
rename qemu_bql into bql_?
- Could we keep the full spell of BQL at some places, so people can still
reference it if not familiar? IIUC most of the BQL helpers will root
back to the major three functions (_lock, _unlock, _locked), perhaps
add a comment of "BQL stands for..." over these three functions as
comment?
Please take or ignore these nitpicks; my ACK will stand irrelevant.
Thanks,
--
Peter Xu
