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Tue, 10 Mar 2020 15:32:56 +0000 (UTC) Received: from dresden.str.redhat.com (unknown [10.36.118.149]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7776F60BF4; Tue, 10 Mar 2020 15:32:54 +0000 (UTC) Subject: Re: [PATCH v3 8/9] block/block-copy: reduce intersecting request lock To: Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org References: <20200306073831.7737-1-vsementsov@virtuozzo.com> <20200306073831.7737-9-vsementsov@virtuozzo.com> From: Max Reitz Autocrypt: addr=mreitz@redhat.com; prefer-encrypt=mutual; keydata= mQENBFXOJlcBCADEyyhOTsoa/2ujoTRAJj4MKA21dkxxELVj3cuILpLTmtachWj7QW+TVG8U /PsMCFbpwsQR7oEy8eHHZwuGQsNpEtNC2G/L8Yka0BIBzv7dEgrPzIu+W3anZXQW4702+uES U29G8TP/NGfXRRHGlbBIH9KNUnOSUD2vRtpOLXkWsV5CN6vQFYgQfFvmp5ZpPeUe6xNplu8V mcTw8OSEDW/ZnxJc8TekCKZSpdzYoxfzjm7xGmZqB18VFwgJZlIibt1HE0EB4w5GsD7x5ekh awIe3RwoZgZDLQMdOitJ1tUc8aqaxvgA4tz6J6st8D8pS//m1gAoYJWGwwIVj1DjTYLtABEB AAG0HU1heCBSZWl0eiA8bXJlaXR6QHJlZGhhdC5jb20+iQFTBBMBCAA9AhsDBQkSzAMABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheABQJVzie5FRhoa3A6Ly9rZXlzLmdudXBnLm5ldAAKCRD0 B9sAYdXPQDcIB/9uNkbYEex1rHKz3mr12uxYMwLOOFY9fstP5aoVJQ1nWQVB6m2cfKGdcRe1 2/nFaHSNAzT0NnKz2MjhZVmcrpyd2Gp2QyISCfb1FbT82GMtXFj1wiHmPb3CixYmWGQUUh+I AvUqsevLA+WihgBUyaJq/vuDVM1/K9Un+w+Tz5vpeMidlIsTYhcsMhn0L9wlCjoucljvbDy/ 8C9L2DUdgi3XTa0ORKeflUhdL4gucWoAMrKX2nmPjBMKLgU7WLBc8AtV+84b9OWFML6NEyo4 4cP7cM/07VlJK53pqNg5cHtnWwjHcbpGkQvx6RUx6F1My3y52vM24rNUA3+ligVEgPYBuQEN BFXOJlcBCADAmcVUNTWT6yLWQHvxZ0o47KCP8OcLqD+67T0RCe6d0LP8GsWtrJdeDIQk+T+F xO7DolQPS6iQ6Ak2/lJaPX8L0BkEAiMuLCKFU6Bn3lFOkrQeKp3u05wCSV1iKnhg0UPji9V2 W5eNfy8F4ZQHpeGUGy+liGXlxqkeRVhLyevUqfU0WgNqAJpfhHSGpBgihUupmyUg7lfUPeRM DzAN1pIqoFuxnN+BRHdAecpsLcbR8sQddXmDg9BpSKozO/JyBmaS1RlquI8HERQoe6EynJhd 64aICHDfj61rp+/0jTIcevxIIAzW70IadoS/y3DVIkuhncgDBvGbF3aBtjrJVP+5ABEBAAGJ ASUEGAEIAA8FAlXOJlcCGwwFCRLMAwAACgkQ9AfbAGHVz0CbFwf9F/PXxQR9i4N0iipISYjU sxVdjJOM2TMut+ZZcQ6NSMvhZ0ogQxJ+iEQ5OjnIputKvPVd5U7WRh+4lF1lB/NQGrGZQ1ic alkj6ocscQyFwfib+xIe9w8TG1CVGkII7+TbS5pXHRxZH1niaRpoi/hYtgzkuOPp35jJyqT/ /ELbqQTDAWcqtJhzxKLE/ugcOMK520dJDeb6x2xVES+S5LXby0D4juZlvUj+1fwZu+7Io5+B bkhSVPb/QdOVTpnz7zWNyNw+OONo1aBUKkhq2UIByYXgORPFnbfMY7QWHcjpBVw9MgC4tGeF R4bv+1nAMMxKmb5VvQCExr0eFhJUAHAhVg== Message-ID: Date: Tue, 10 Mar 2020 16:32:52 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200306073831.7737-9-vsementsov@virtuozzo.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="zG4kBNkr5JTX3hUbLRUGMzabqXC8fwEm4" X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 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: kwolf@redhat.com, andrey.shinkevich@virtuozzo.com, jsnow@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --zG4kBNkr5JTX3hUbLRUGMzabqXC8fwEm4 Content-Type: multipart/mixed; boundary="4cbhubXc3lC6FtfrjiEgZRREUwtNl9Hof" --4cbhubXc3lC6FtfrjiEgZRREUwtNl9Hof Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 06.03.20 08:38, Vladimir Sementsov-Ogievskiy wrote: > Currently, block_copy operation lock the whole requested region. But > there is no reason to lock clusters, which are already copied, it will > disturb other parallel block_copy requests for no reason. >=20 > Let's instead do the following: >=20 > Lock only sub-region, which we are going to operate on. Then, after > copying all dirty sub-regions, we should wait for intersecting > requests block-copy, if they failed, we should retry these new dirty > clusters. >=20 > Signed-off-by: Vladimir Sementsov-Ogievskiy > Reviewed-by: Andrey Shinkevich > --- > block/block-copy.c | 128 ++++++++++++++++++++++++++++++++++++--------- > 1 file changed, 104 insertions(+), 24 deletions(-) >=20 > diff --git a/block/block-copy.c b/block/block-copy.c > index 2b29131653..d66b8eb691 100644 > --- a/block/block-copy.c > +++ b/block/block-copy.c [...] > +/* Called only on full-dirty region */ > static void block_copy_inflight_req_begin(BlockCopyState *s, > BlockCopyInFlightReq *req, > int64_t offset, int64_t bytes) > { > + assert(!find_conflicting_inflight_req(s, offset, bytes)); > + > + bdrv_reset_dirty_bitmap(s->copy_bitmap, offset, bytes); > + s->in_flight_bytes +=3D bytes; > + > req->offset =3D offset; > req->bytes =3D bytes; > qemu_co_queue_init(&req->wait_queue); > QLIST_INSERT_HEAD(&s->inflight_reqs, req, list); > } > =20 > -static void coroutine_fn block_copy_inflight_req_end(BlockCopyInFlightRe= q *req) > +/* > + * block_copy_inflight_req_shrink > + * > + * Drop the tail of the request to be handled later. Set dirty bits back= and > + * wake up all requests waiting for us (may be some of them are not inte= rsecting > + * with shrunk request) > + */ > +static void coroutine_fn block_copy_inflight_req_shrink(BlockCopyState *= s, > + BlockCopyInFlightReq *req, int64_t new_bytes) > { > + if (new_bytes =3D=3D req->bytes) { > + return; > + } > + > + assert(new_bytes > 0 && new_bytes < req->bytes); > + > + bdrv_set_dirty_bitmap(s->copy_bitmap, > + req->offset + new_bytes, req->bytes - new_byte= s); I think we need to reduce in_flight_bytes here. > + > + req->bytes =3D new_bytes; > + qemu_co_queue_restart_all(&req->wait_queue); > +} > + > +static void coroutine_fn block_copy_inflight_req_end(BlockCopyState *s, > + BlockCopyInFlightRe= q *req, > + int ret) > +{ > + s->in_flight_bytes -=3D req->bytes; > + if (ret < 0) { > + bdrv_set_dirty_bitmap(s->copy_bitmap, req->offset, req->bytes); > + } > QLIST_REMOVE(req, list); > qemu_co_queue_restart_all(&req->wait_queue); > } [...] > @@ -432,7 +479,40 @@ int coroutine_fn block_copy(BlockCopyState *s, > bytes -=3D cur_bytes; > } > =20 > - block_copy_inflight_req_end(&req); > + return found_dirty; > +} > + > +/* > + * block_copy > + * > + * Copy requested region, accordingly to dirty bitmap. > + * Collaborate with parallel block_copy requests: if they success it hel= p us. If s/success/succeed/, s/it help/it will help/ > + * they fail, we retry not-copied regions. So, if we return error, it me= ans that s/retry/will retry/ (In theory also s/it means/it will mean/, but I suppose that also works as-is.) > + * io operation failed in context of _this_ block_copy call, not some pa= rallel Perhaps rather =93some I/O operation failed in the context of [=85]=94? > + * operation. > + */ > +int coroutine_fn block_copy(BlockCopyState *s, int64_t offset, int64_t b= ytes, > + bool *error_is_read) > +{ > + int ret; > + > + do { > + ret =3D block_copy_dirty_clusters(s, offset, bytes, error_is_rea= d); > + > + if (ret =3D=3D 0) { > + ret =3D block_copy_wait_one(s, offset, bytes); > + } > + > + /* > + * We retry in two cases: > + * 1. Some progress done > + * Something was copied, which means that there were yield po= ints > + * and some new dirty bits may have appeared (due to failed p= arallel > + * block-copy requests). > + * 2. We have waited for some intersecting block-copy request > + * It may have failed and produced new dirty bits. > + */ > + } while (ret > 0); > =20 > return ret; > } This new code looks good. Max --4cbhubXc3lC6FtfrjiEgZRREUwtNl9Hof-- --zG4kBNkr5JTX3hUbLRUGMzabqXC8fwEm4 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl5nsyQACgkQ9AfbAGHV z0DvIwf/SWGr56EFduk50TgC09hX8DIoAACCp0OqxIVujzK5I5neuABAcj05peUt THG35UTrPK31o50agFrWqyPpB9So+D5FoEGAc9j7J16xDtPuVS6CYraSNrQk36GG OBoK2rmWArcDeAzcS8pRJxlMTvePijF3dA03qhECWjd1qUy+p03Y81FW9A+LS6Ps Pe82ls/lVKdPDe4jhNKx8PW4baJOv2jMrwHzREO38cs0exrQGzUEOcJBThtyNIbK OQPcmrCS3uHRHZHxgHTnDN/7VEi4AAmjeE9FzDC4S+9OazHSQTddN/T1JJhoNeQT /wCF0syJx0iSBwFW67EUOe3izrVeyQ== =PxRS -----END PGP SIGNATURE----- --zG4kBNkr5JTX3hUbLRUGMzabqXC8fwEm4--