ping
On 27/09/2021 15:07, Li Zhijian wrote:
> destination:
> ../qemu/build/qemu-system-x86_64 -enable-kvm -netdev
> tap,id=hn0,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown -device
> e1000,netdev=hn0,mac=50:52:54:00:11:22 -boot c -drive
> if=none,file=./Fedora-rdma-server-migration.qcow2,id=drive-virtio-disk0
> -device
> virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0 -m
> 2048 -smp 2 -device piix3-usb-uhci -device usb-tablet -monitor stdio -vga qxl
> -spice streaming-video=filter,port=5902,disable-ticketing -incoming
> rdma:192.168.22.23:8888
> qemu-system-x86_64: -spice
> streaming-video=filter,port=5902,disable-ticketing: warning: short-form
> boolean option 'disable-ticketing' deprecated
> Please use disable-ticketing=on instead
> QEMU 6.0.50 monitor - type 'help' for more information
> (qemu) trace-event qemu_rdma_block_for_wrid_miss on
> (qemu) dest_init RDMA Device opened: kernel name rxe_eth0 uverbs device name
> uverbs2, infiniband_verbs class device path
> /sys/class/infiniband_verbs/uverbs2, infiniband class device path
> /sys/class/infiniband/rxe_eth0, transport: (2) Ethernet
> qemu_rdma_block_for_wrid_miss A Wanted wrid CONTROL SEND (2000) but got
> CONTROL RECV (4000)
>
> source:
> ../qemu/build/qemu-system-x86_64 -enable-kvm -netdev
> tap,id=hn0,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown -device
> e1000,netdev=hn0,mac=50:52:54:00:11:22 -boot c -drive
> if=none,file=./Fedora-rdma-server.qcow2,id=drive-virtio-disk0 -device
> virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0 -m
> 2048 -smp 2 -device piix3-usb-uhci -device usb-tablet -monitor stdio -vga qxl
> -spice streaming-video=filter,port=5901,disable-ticketing -S
> qemu-system-x86_64: -spice
> streaming-video=filter,port=5901,disable-ticketing: warning: short-form
> boolean option 'disable-ticketing' deprecated
> Please use disable-ticketing=on instead
> QEMU 6.0.50 monitor - type 'help' for more information
> (qemu)
> (qemu) trace-event qemu_rdma_block_for_wrid_miss on
> (qemu) migrate -d rdma:192.168.22.23:8888
> source_resolve_host RDMA Device opened: kernel name rxe_eth0 uverbs device
> name uverbs2, infiniband_verbs class device path
> /sys/class/infiniband_verbs/uverbs2, infiniband class device path
> /sys/class/infiniband/rxe_eth0, transport: (2) Ethernet
> (qemu) qemu_rdma_block_for_wrid_miss A Wanted wrid WRITE RDMA (1) but got
> CONTROL RECV (4000)
>
> NOTE: we use soft RoCE as the rdma device.
> [root@iaas-rpma images]# rdma link show rxe_eth0/1
> link rxe_eth0/1 state ACTIVE physical_state LINK_UP netdev eth0
>
> This migration could not be completed when out of order(OOO) CQ event occurs.
> The send queue and receive queue shared a same completion queue, and
> qemu_rdma_block_for_wrid() will drop the CQs it's not interested in. But
> the dropped CQs by qemu_rdma_block_for_wrid() could be later CQs it wants.
> So in this case, qemu_rdma_block_for_wrid() will block forever.
>
> OOO cases will occur in both source side and destination side. And a
> forever blocking happens on only SEND and RECV are out of order. OOO between
> 'WRITE RDMA' and 'RECV' doesn't matter.
>
> below the OOO sequence:
> source destination
> rdma_write_one() qemu_rdma_registration_handle()
> 1. S1: post_recv X D1: post_recv Y
> 2. wait for recv CQ event X
> 3. D2: post_send X ---------------+
> 4. wait for send CQ send event X (D2) |
> 5. recv CQ event X reaches (D2) |
> 6. +-S2: post_send Y |
> 7. | wait for send CQ event Y |
> 8. | recv CQ event Y (S2) (drop it) |
> 9. +-send CQ event Y reaches (S2) |
> 10. send CQ event X reaches (D2) -----+
> 11. wait recv CQ event Y (dropped by (8))
>
> Although a hardware IB works fine in my a hundred of runs, the IB
> specification
> doesn't guaratee the CQ order in such case.
>
> Here we introduce a independent send completion queue to distinguish
> ibv_post_send completion queue from the original mixed completion queue.
> It helps us to poll the specific CQE we are really interested in.
>
> Signed-off-by: Li Zhijian <lizhij...@cn.fujitsu.com>
> ---
> V3: rebase code, and combine 2/2 to 1/2
> V2: Introduce send completion queue
> ---
> migration/rdma.c | 132 +++++++++++++++++++++++++++++++++++------------
> 1 file changed, 98 insertions(+), 34 deletions(-)
>
> diff --git a/migration/rdma.c b/migration/rdma.c
> index 5c2d113aa94..bb19a5afe73 100644
> --- a/migration/rdma.c
> +++ b/migration/rdma.c
> @@ -358,9 +358,11 @@ typedef struct RDMAContext {
> struct ibv_context *verbs;
> struct rdma_event_channel *channel;
> struct ibv_qp *qp; /* queue pair */
> - struct ibv_comp_channel *comp_channel; /* completion channel */
> + struct ibv_comp_channel *recv_comp_channel; /* recv completion channel
> */
> + struct ibv_comp_channel *send_comp_channel; /* send completion channel
> */
> struct ibv_pd *pd; /* protection domain */
> - struct ibv_cq *cq; /* completion queue */
> + struct ibv_cq *recv_cq; /* recvieve completion queue */
> + struct ibv_cq *send_cq; /* send completion queue */
>
> /*
> * If a previous write failed (perhaps because of a failed
> @@ -1060,19 +1062,32 @@ static int qemu_rdma_alloc_pd_cq(RDMAContext *rdma)
> }
>
> /* create completion channel */
> - rdma->comp_channel = ibv_create_comp_channel(rdma->verbs);
> - if (!rdma->comp_channel) {
> + rdma->recv_comp_channel = ibv_create_comp_channel(rdma->verbs);
> + if (!rdma->recv_comp_channel) {
> error_report("failed to allocate completion channel");
> goto err_alloc_pd_cq;
> }
>
> /*
> - * Completion queue can be filled by both read and write work requests,
> - * so must reflect the sum of both possible queue sizes.
> + * Completion queue can be filled by read work requests.
> */
> - rdma->cq = ibv_create_cq(rdma->verbs, (RDMA_SIGNALED_SEND_MAX * 3),
> - NULL, rdma->comp_channel, 0);
> - if (!rdma->cq) {
> + rdma->recv_cq = ibv_create_cq(rdma->verbs, (RDMA_SIGNALED_SEND_MAX * 3),
> + NULL, rdma->recv_comp_channel, 0);
> + if (!rdma->recv_cq) {
> + error_report("failed to allocate completion queue");
> + goto err_alloc_pd_cq;
> + }
> +
> + /* create send completion channel */
> + rdma->send_comp_channel = ibv_create_comp_channel(rdma->verbs);
> + if (!rdma->send_comp_channel) {
> + error_report("failed to allocate completion channel");
> + goto err_alloc_pd_cq;
> + }
> +
> + rdma->send_cq = ibv_create_cq(rdma->verbs, (RDMA_SIGNALED_SEND_MAX * 3),
> + NULL, rdma->send_comp_channel, 0);
> + if (!rdma->send_cq) {
> error_report("failed to allocate completion queue");
> goto err_alloc_pd_cq;
> }
> @@ -1083,11 +1098,19 @@ err_alloc_pd_cq:
> if (rdma->pd) {
> ibv_dealloc_pd(rdma->pd);
> }
> - if (rdma->comp_channel) {
> - ibv_destroy_comp_channel(rdma->comp_channel);
> + if (rdma->recv_comp_channel) {
> + ibv_destroy_comp_channel(rdma->recv_comp_channel);
> + }
> + if (rdma->send_comp_channel) {
> + ibv_destroy_comp_channel(rdma->send_comp_channel);
> + }
> + if (rdma->recv_cq) {
> + ibv_destroy_cq(rdma->recv_cq);
> + rdma->recv_cq = NULL;
> }
> rdma->pd = NULL;
> - rdma->comp_channel = NULL;
> + rdma->recv_comp_channel = NULL;
> + rdma->send_comp_channel = NULL;
> return -1;
>
> }
> @@ -1104,8 +1127,8 @@ static int qemu_rdma_alloc_qp(RDMAContext *rdma)
> attr.cap.max_recv_wr = 3;
> attr.cap.max_send_sge = 1;
> attr.cap.max_recv_sge = 1;
> - attr.send_cq = rdma->cq;
> - attr.recv_cq = rdma->cq;
> + attr.send_cq = rdma->send_cq;
> + attr.recv_cq = rdma->recv_cq;
> attr.qp_type = IBV_QPT_RC;
>
> ret = rdma_create_qp(rdma->cm_id, rdma->pd, &attr);
> @@ -1421,14 +1444,14 @@ static void qemu_rdma_signal_unregister(RDMAContext
> *rdma, uint64_t index,
> * (of any kind) has completed.
> * Return the work request ID that completed.
> */
> -static uint64_t qemu_rdma_poll(RDMAContext *rdma, uint64_t *wr_id_out,
> - uint32_t *byte_len)
> +static uint64_t qemu_rdma_poll(RDMAContext *rdma, struct ibv_cq *cq,
> + uint64_t *wr_id_out, uint32_t *byte_len)
> {
> int ret;
> struct ibv_wc wc;
> uint64_t wr_id;
>
> - ret = ibv_poll_cq(rdma->cq, 1, &wc);
> + ret = ibv_poll_cq(cq, 1, &wc);
>
> if (!ret) {
> *wr_id_out = RDMA_WRID_NONE;
> @@ -1500,7 +1523,8 @@ static uint64_t qemu_rdma_poll(RDMAContext *rdma,
> uint64_t *wr_id_out,
> /* Wait for activity on the completion channel.
> * Returns 0 on success, none-0 on error.
> */
> -static int qemu_rdma_wait_comp_channel(RDMAContext *rdma)
> +static int qemu_rdma_wait_comp_channel(RDMAContext *rdma,
> + struct ibv_comp_channel *comp_channel)
> {
> struct rdma_cm_event *cm_event;
> int ret = -1;
> @@ -1511,7 +1535,7 @@ static int qemu_rdma_wait_comp_channel(RDMAContext
> *rdma)
> */
> if (rdma->migration_started_on_destination &&
> migration_incoming_get_current()->state == MIGRATION_STATUS_ACTIVE)
> {
> - yield_until_fd_readable(rdma->comp_channel->fd);
> + yield_until_fd_readable(comp_channel->fd);
> } else {
> /* This is the source side, we're in a separate thread
> * or destination prior to migration_fd_process_incoming()
> @@ -1522,7 +1546,7 @@ static int qemu_rdma_wait_comp_channel(RDMAContext
> *rdma)
> */
> while (!rdma->error_state && !rdma->received_error) {
> GPollFD pfds[2];
> - pfds[0].fd = rdma->comp_channel->fd;
> + pfds[0].fd = comp_channel->fd;
> pfds[0].events = G_IO_IN | G_IO_HUP | G_IO_ERR;
> pfds[0].revents = 0;
>
> @@ -1580,6 +1604,17 @@ static int qemu_rdma_wait_comp_channel(RDMAContext
> *rdma)
> return rdma->error_state;
> }
>
> +static struct ibv_comp_channel *to_channel(RDMAContext *rdma, int wrid)
> +{
> + return wrid < RDMA_WRID_RECV_CONTROL ? rdma->send_comp_channel :
> + rdma->recv_comp_channel;
> +}
> +
> +static struct ibv_cq *to_cq(RDMAContext *rdma, int wrid)
> +{
> + return wrid < RDMA_WRID_RECV_CONTROL ? rdma->send_cq : rdma->recv_cq;
> +}
> +
> /*
> * Block until the next work request has completed.
> *
> @@ -1600,13 +1635,15 @@ static int qemu_rdma_block_for_wrid(RDMAContext
> *rdma, int wrid_requested,
> struct ibv_cq *cq;
> void *cq_ctx;
> uint64_t wr_id = RDMA_WRID_NONE, wr_id_in;
> + struct ibv_comp_channel *ch = to_channel(rdma, wrid_requested);
> + struct ibv_cq *poll_cq = to_cq(rdma, wrid_requested);
>
> - if (ibv_req_notify_cq(rdma->cq, 0)) {
> + if (ibv_req_notify_cq(poll_cq, 0)) {
> return -1;
> }
> /* poll cq first */
> while (wr_id != wrid_requested) {
> - ret = qemu_rdma_poll(rdma, &wr_id_in, byte_len);
> + ret = qemu_rdma_poll(rdma, poll_cq, &wr_id_in, byte_len);
> if (ret < 0) {
> return ret;
> }
> @@ -1627,12 +1664,12 @@ static int qemu_rdma_block_for_wrid(RDMAContext
> *rdma, int wrid_requested,
> }
>
> while (1) {
> - ret = qemu_rdma_wait_comp_channel(rdma);
> + ret = qemu_rdma_wait_comp_channel(rdma, ch);
> if (ret) {
> goto err_block_for_wrid;
> }
>
> - ret = ibv_get_cq_event(rdma->comp_channel, &cq, &cq_ctx);
> + ret = ibv_get_cq_event(ch, &cq, &cq_ctx);
> if (ret) {
> perror("ibv_get_cq_event");
> goto err_block_for_wrid;
> @@ -1646,7 +1683,7 @@ static int qemu_rdma_block_for_wrid(RDMAContext *rdma,
> int wrid_requested,
> }
>
> while (wr_id != wrid_requested) {
> - ret = qemu_rdma_poll(rdma, &wr_id_in, byte_len);
> + ret = qemu_rdma_poll(rdma, poll_cq, &wr_id_in, byte_len);
> if (ret < 0) {
> goto err_block_for_wrid;
> }
> @@ -2362,13 +2399,21 @@ static void qemu_rdma_cleanup(RDMAContext *rdma)
> rdma_destroy_qp(rdma->cm_id);
> rdma->qp = NULL;
> }
> - if (rdma->cq) {
> - ibv_destroy_cq(rdma->cq);
> - rdma->cq = NULL;
> + if (rdma->recv_cq) {
> + ibv_destroy_cq(rdma->recv_cq);
> + rdma->recv_cq = NULL;
> + }
> + if (rdma->send_cq) {
> + ibv_destroy_cq(rdma->send_cq);
> + rdma->send_cq = NULL;
> }
> - if (rdma->comp_channel) {
> - ibv_destroy_comp_channel(rdma->comp_channel);
> - rdma->comp_channel = NULL;
> + if (rdma->recv_comp_channel) {
> + ibv_destroy_comp_channel(rdma->recv_comp_channel);
> + rdma->recv_comp_channel = NULL;
> + }
> + if (rdma->send_comp_channel) {
> + ibv_destroy_comp_channel(rdma->send_comp_channel);
> + rdma->send_comp_channel = NULL;
> }
> if (rdma->pd) {
> ibv_dealloc_pd(rdma->pd);
> @@ -3040,10 +3085,14 @@ static void
> qio_channel_rdma_set_aio_fd_handler(QIOChannel *ioc,
> {
> QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(ioc);
> if (io_read) {
> - aio_set_fd_handler(ctx, rioc->rdmain->comp_channel->fd,
> + aio_set_fd_handler(ctx, rioc->rdmain->recv_comp_channel->fd,
> + false, io_read, io_write, NULL, opaque);
> + aio_set_fd_handler(ctx, rioc->rdmain->send_comp_channel->fd,
> false, io_read, io_write, NULL, opaque);
> } else {
> - aio_set_fd_handler(ctx, rioc->rdmaout->comp_channel->fd,
> + aio_set_fd_handler(ctx, rioc->rdmaout->recv_comp_channel->fd,
> + false, io_read, io_write, NULL, opaque);
> + aio_set_fd_handler(ctx, rioc->rdmaout->send_comp_channel->fd,
> false, io_read, io_write, NULL, opaque);
> }
> }
> @@ -3257,7 +3306,22 @@ static size_t qemu_rdma_save_page(QEMUFile *f, void
> *opaque,
> */
> while (1) {
> uint64_t wr_id, wr_id_in;
> - int ret = qemu_rdma_poll(rdma, &wr_id_in, NULL);
> + int ret = qemu_rdma_poll(rdma, rdma->recv_cq, &wr_id_in, NULL);
> + if (ret < 0) {
> + error_report("rdma migration: polling error! %d", ret);
> + goto err;
> + }
> +
> + wr_id = wr_id_in & RDMA_WRID_TYPE_MASK;
> +
> + if (wr_id == RDMA_WRID_NONE) {
> + break;
> + }
> + }
> +
> + while (1) {
> + uint64_t wr_id, wr_id_in;
> + int ret = qemu_rdma_poll(rdma, rdma->send_cq, &wr_id_in, NULL);
> if (ret < 0) {
> error_report("rdma migration: polling error! %d", ret);
> goto err;
