| Message ID | 20210823033358.3002-3-lizhijian@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | enable fsdax rdma migration | expand |
CCing Marcel On 23/08/2021 11:33, Li Zhijian wrote: > The responder mr registering with ODP will sent RNR NAK back to > the requester in the face of the page fault. > --------- > ibv_poll_cq wc.status=13 RNR retry counter exceeded! > ibv_poll_cq wrid=WRITE RDMA! > --------- > ibv_advise_mr(3) helps to make pages present before the actual IO is > conducted so that the responder does page fault as little as possible. > > Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com> > Reviewed-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com> > > --- > V2: use IBV_ADVISE_MR_FLAG_FLUSH instead of IB_UVERBS_ADVISE_MR_FLAG_FLUSH > and add Reviewed-by tag. # Marcel > --- > migration/rdma.c | 40 ++++++++++++++++++++++++++++++++++++++++ > migration/trace-events | 1 + > 2 files changed, 41 insertions(+) > > diff --git a/migration/rdma.c b/migration/rdma.c > index eb80431aae2..6c2cc3f617c 100644 > --- a/migration/rdma.c > +++ b/migration/rdma.c > @@ -1133,6 +1133,30 @@ static bool rdma_support_odp(struct ibv_context *dev) > return false; > } > > +/* > + * ibv_advise_mr to avoid RNR NAK error as far as possible. > + * The responder mr registering with ODP will sent RNR NAK back to > + * the requester in the face of the page fault. > + */ > +static void qemu_rdma_advise_prefetch_mr(struct ibv_pd *pd, uint64_t addr, > + uint32_t len, uint32_t lkey, > + const char *name, bool wr) > +{ > + int ret; > + int advice = wr ? IBV_ADVISE_MR_ADVICE_PREFETCH_WRITE : > + IBV_ADVISE_MR_ADVICE_PREFETCH; > + struct ibv_sge sg_list = {.lkey = lkey, .addr = addr, .length = len}; > + > + ret = ibv_advise_mr(pd, advice, > + IBV_ADVISE_MR_FLAG_FLUSH, &sg_list, 1); > + /* ignore the error */ > + if (ret) { > + trace_qemu_rdma_advise_mr(name, len, addr, strerror(errno)); > + } else { > + trace_qemu_rdma_advise_mr(name, len, addr, "successed"); > + } > +} > + > static int qemu_rdma_reg_whole_ram_blocks(RDMAContext *rdma) > { > int i; > @@ -1156,6 +1180,15 @@ static int qemu_rdma_reg_whole_ram_blocks(RDMAContext *rdma) > local->block[i].local_host_addr, > local->block[i].length, access); > trace_qemu_rdma_register_odp_mr(local->block[i].block_name); > + > + if (local->block[i].mr) { > + qemu_rdma_advise_prefetch_mr(rdma->pd, > + (uintptr_t)local->block[i].local_host_addr, > + local->block[i].length, > + local->block[i].mr->lkey, > + local->block[i].block_name, > + true); > + } > } > > if (!local->block[i].mr) { > @@ -1255,6 +1288,13 @@ static int qemu_rdma_register_and_get_keys(RDMAContext *rdma, > /* register ODP mr */ > block->pmr[chunk] = ibv_reg_mr(rdma->pd, chunk_start, len, access); > trace_qemu_rdma_register_odp_mr(block->block_name); > + > + if (block->pmr[chunk]) { > + qemu_rdma_advise_prefetch_mr(rdma->pd, (uintptr_t)chunk_start, > + len, block->pmr[chunk]->lkey, > + block->block_name, rkey); > + > + } > } > } > if (!block->pmr[chunk]) { > diff --git a/migration/trace-events b/migration/trace-events > index 5f6aa580def..a8ae163707c 100644 > --- a/migration/trace-events > +++ b/migration/trace-events > @@ -213,6 +213,7 @@ qemu_rdma_poll_other(const char *compstr, int64_t comp, int left) "other complet > qemu_rdma_post_send_control(const char *desc) "CONTROL: sending %s.." > qemu_rdma_register_and_get_keys(uint64_t len, void *start) "Registering %" PRIu64 " bytes @ %p" > qemu_rdma_register_odp_mr(const char *name) "Try to register On-Demand Paging memory region: %s" > +qemu_rdma_advise_mr(const char *name, uint32_t len, uint64_t addr, const char *res) "Try to advise block %s prefetch at %" PRIu32 "@0x%" PRIx64 ": %s" > qemu_rdma_registration_handle_compress(int64_t length, int index, int64_t offset) "Zapping zero chunk: %" PRId64 " bytes, index %d, offset %" PRId64 > qemu_rdma_registration_handle_finished(void) "" > qemu_rdma_registration_handle_ram_blocks(void) ""
diff --git a/migration/rdma.c b/migration/rdma.c index eb80431aae2..6c2cc3f617c 100644 --- a/migration/rdma.c +++ b/migration/rdma.c @@ -1133,6 +1133,30 @@ static bool rdma_support_odp(struct ibv_context *dev) return false; } +/* + * ibv_advise_mr to avoid RNR NAK error as far as possible. + * The responder mr registering with ODP will sent RNR NAK back to + * the requester in the face of the page fault. + */ +static void qemu_rdma_advise_prefetch_mr(struct ibv_pd *pd, uint64_t addr, + uint32_t len, uint32_t lkey, + const char *name, bool wr) +{ + int ret; + int advice = wr ? IBV_ADVISE_MR_ADVICE_PREFETCH_WRITE : + IBV_ADVISE_MR_ADVICE_PREFETCH; + struct ibv_sge sg_list = {.lkey = lkey, .addr = addr, .length = len}; + + ret = ibv_advise_mr(pd, advice, + IBV_ADVISE_MR_FLAG_FLUSH, &sg_list, 1); + /* ignore the error */ + if (ret) { + trace_qemu_rdma_advise_mr(name, len, addr, strerror(errno)); + } else { + trace_qemu_rdma_advise_mr(name, len, addr, "successed"); + } +} + static int qemu_rdma_reg_whole_ram_blocks(RDMAContext *rdma) { int i; @@ -1156,6 +1180,15 @@ static int qemu_rdma_reg_whole_ram_blocks(RDMAContext *rdma) local->block[i].local_host_addr, local->block[i].length, access); trace_qemu_rdma_register_odp_mr(local->block[i].block_name); + + if (local->block[i].mr) { + qemu_rdma_advise_prefetch_mr(rdma->pd, + (uintptr_t)local->block[i].local_host_addr, + local->block[i].length, + local->block[i].mr->lkey, + local->block[i].block_name, + true); + } } if (!local->block[i].mr) { @@ -1255,6 +1288,13 @@ static int qemu_rdma_register_and_get_keys(RDMAContext *rdma, /* register ODP mr */ block->pmr[chunk] = ibv_reg_mr(rdma->pd, chunk_start, len, access); trace_qemu_rdma_register_odp_mr(block->block_name); + + if (block->pmr[chunk]) { + qemu_rdma_advise_prefetch_mr(rdma->pd, (uintptr_t)chunk_start, + len, block->pmr[chunk]->lkey, + block->block_name, rkey); + + } } } if (!block->pmr[chunk]) { diff --git a/migration/trace-events b/migration/trace-events index 5f6aa580def..a8ae163707c 100644 --- a/migration/trace-events +++ b/migration/trace-events @@ -213,6 +213,7 @@ qemu_rdma_poll_other(const char *compstr, int64_t comp, int left) "other complet qemu_rdma_post_send_control(const char *desc) "CONTROL: sending %s.." qemu_rdma_register_and_get_keys(uint64_t len, void *start) "Registering %" PRIu64 " bytes @ %p" qemu_rdma_register_odp_mr(const char *name) "Try to register On-Demand Paging memory region: %s" +qemu_rdma_advise_mr(const char *name, uint32_t len, uint64_t addr, const char *res) "Try to advise block %s prefetch at %" PRIu32 "@0x%" PRIx64 ": %s" qemu_rdma_registration_handle_compress(int64_t length, int index, int64_t offset) "Zapping zero chunk: %" PRId64 " bytes, index %d, offset %" PRId64 qemu_rdma_registration_handle_finished(void) "" qemu_rdma_registration_handle_ram_blocks(void) ""