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Wed, 20 May 2020 14:49:29 +0000 (UTC) Date: Wed, 20 May 2020 16:49:28 +0200 From: Kevin Wolf To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH v2] block: Factor out bdrv_run_co() Message-ID: <20200520144928.GC5192@linux.fritz.box> References: <20200519175650.31506-1-vsementsov@virtuozzo.com> <20200520140500.GB5192@linux.fritz.box> MIME-Version: 1.0 In-Reply-To: <20200520140500.GB5192@linux.fritz.box> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.120; envelope-from=kwolf@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/20 01:34:51 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fam@euphon.net, qemu-block@nongnu.org, qemu-devel@nongnu.org, mreitz@redhat.com, stefanha@redhat.com, den@openvz.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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 > > Signed-off-by: Vladimir Sementsov-Ogievskiy > > [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. Kevin