20.05.2020 17:49, Kevin Wolf wrote:
Am 20.05.2020 um 16:05 hat Kevin Wolf geschrieben:
Am 19.05.2020 um 19:56 hat Vladimir Sementsov-Ogievskiy geschrieben:
We have a few bdrv_*() functions that can either spawn a new coroutine
and wait for it with BDRV_POLL_WHILE() or use a fastpath if they are
alreeady running in a coroutine. All of them duplicate basically the
same code.
Factor the common code into a new function bdrv_run_co().
Signed-off-by: Kevin Wolf <[email protected]>
Signed-off-by: Vladimir Sementsov-Ogievskiy <[email protected]>
[Factor out bdrv_run_co_entry too]
---
Hi!
I'm a bit lost on rebasing "block/io: safer inc/dec in_flight sections"
(is it needed or not?), so, I decided to send just this one patch:
I suggest to go a bit further, and refactor that bdrv_run_co don't need
additional *ret argument neither NOT_DONE logic.
Hm, this approach adds another indirection and bdrv_pread/pwrite still
seems to be on some hot paths. But maybe this is just the right
motivation to clean up qcow2 a bit and use explicit bdrv_co_*() where it
is possible. I might take a look later.
Still not easily possible it seems. We can add a few coroutine_fn
markers here and there (and probably should do that), but the
interesting I/O is in the Qcow2Cache, which is used from basically
everywhere.
Hmm. Calling *_entry on in-coroutine path is also an extra inderection.
I've posted another solution for this think: auto generation of coroutine
wrappers code, which produce no extra inderection.
RFC was here, a year ago:
https://lists.gnu.org/archive/html/qemu-devel/2019-02/msg05322.html
May be, it's time to resend it, as your point gives it a point.
--
Best regards,
Vladimir
