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[2603:8081:140c:1a00:7fc0:37e:f57e:caea]) by smtp.gmail.com with ESMTPSA id w1-20020a056830060100b006060322125esm1258516oti.46.2022.05.13.11.22.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 May 2022 11:22:09 -0700 (PDT) Message-ID: <25c4e1f7-54eb-456b-8020-b3b1e24a9ecb@gmail.com> Date: Fri, 13 May 2022 13:22:08 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH for-rc] RDMA/rxe: Fix rnr retry behavior Content-Language: en-US To: Yanjun Zhu , jgg@nvidia.com, zyjzyj2000@gmail.com, linux-rdma@vger.kernel.org References: <20220512194901.76696-1-rpearsonhpe@gmail.com> <36f6e476-9762-6d39-e167-abb8dcc9f2bb@linux.dev> From: Bob Pearson In-Reply-To: <36f6e476-9762-6d39-e167-abb8dcc9f2bb@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On 5/13/22 08:38, Yanjun Zhu wrote: > > > 在 2022/5/13 10:40, Yanjun Zhu 写道: >> 在 2022/5/13 3:49, Bob Pearson 写道: >>> Currently the completer tasklet when it sets the retransmit timer or the >>> nak timer sets the same flag (qp->req.need_retry) so that if either >>> timer fires it will attempt to perform a retry flow on the send queue. >>> This has the effect of responding to an RNR NAK at the first retransmit >>> timer event which does not allow for the requested rnr timeout. >>> >>> This patch adds a new flag (qp->req.need_rnr_timeout) which, if set, >>> prevents a retry flow until the rnr nak timer fires. >>> >>> This patch fixes rnr retry errors which can be observed by running the >>> pyverbs test suite 50-100X. With this patch applied they do not occur. >> >> Do you mean that running run_tests.py for 50-100times can reproduce this bug? I want to reproduce this problem. > > Running run_tests.py for 50-100times, I can not reproduce this problem I went back and looked. The occasionally failing test case is: test_rdmacm_async_traffic_external_qp This test is normally skipped for rxe because of a hack in /tests/base.py. I sent you a patch that enables these tests a few days ago. It randomly causes an rnr retry about 1/3 of the time. Most of these are repaired by the retry timer going off. A few ~1-2% are not. Bob > > Zhu Yanjun > >> >> Thanks a lot. >> Zhu Yanjun >> >>> >>> Link: https://lore.kernel.org/linux-rdma/a8287823-1408-4273-bc22-99a0678db640@gmail.com/ >>> Fixes: 8700e3e7c485 ("Soft RoCE (RXE) - The software RoCE driver") >>> Signed-off-by: Bob Pearson >>> --- >>>   drivers/infiniband/sw/rxe/rxe_comp.c  | 4 +--- >>>   drivers/infiniband/sw/rxe/rxe_qp.c    | 1 + >>>   drivers/infiniband/sw/rxe/rxe_req.c   | 6 ++++-- >>>   drivers/infiniband/sw/rxe/rxe_verbs.h | 1 + >>>   4 files changed, 7 insertions(+), 5 deletions(-) >>> >>> diff --git a/drivers/infiniband/sw/rxe/rxe_comp.c b/drivers/infiniband/sw/rxe/rxe_comp.c >>> index 138b3e7d3a5f..bc668cb211b1 100644 >>> --- a/drivers/infiniband/sw/rxe/rxe_comp.c >>> +++ b/drivers/infiniband/sw/rxe/rxe_comp.c >>> @@ -733,9 +733,7 @@ int rxe_completer(void *arg) >>>                   if (qp->comp.rnr_retry != 7) >>>                       qp->comp.rnr_retry--; >>> -                qp->req.need_retry = 1; >>> -                pr_debug("qp#%d set rnr nak timer\n", >>> -                     qp_num(qp)); >>> +                qp->req.need_rnr_timeout = 1; >>>                   mod_timer(&qp->rnr_nak_timer, >>>                         jiffies + rnrnak_jiffies(aeth_syn(pkt) >>>                           & ~AETH_TYPE_MASK)); >>> diff --git a/drivers/infiniband/sw/rxe/rxe_qp.c b/drivers/infiniband/sw/rxe/rxe_qp.c >>> index 62acf890af6c..1c962468714e 100644 >>> --- a/drivers/infiniband/sw/rxe/rxe_qp.c >>> +++ b/drivers/infiniband/sw/rxe/rxe_qp.c >>> @@ -513,6 +513,7 @@ static void rxe_qp_reset(struct rxe_qp *qp) >>>       atomic_set(&qp->ssn, 0); >>>       qp->req.opcode = -1; >>>       qp->req.need_retry = 0; >>> +    qp->req.need_rnr_timeout = 0; >>>       qp->req.noack_pkts = 0; >>>       qp->resp.msn = 0; >>>       qp->resp.opcode = -1; >>> diff --git a/drivers/infiniband/sw/rxe/rxe_req.c b/drivers/infiniband/sw/rxe/rxe_req.c >>> index ae5fbc79dd5c..770ae4279f73 100644 >>> --- a/drivers/infiniband/sw/rxe/rxe_req.c >>> +++ b/drivers/infiniband/sw/rxe/rxe_req.c >>> @@ -103,7 +103,8 @@ void rnr_nak_timer(struct timer_list *t) >>>   { >>>       struct rxe_qp *qp = from_timer(qp, t, rnr_nak_timer); >>> -    pr_debug("qp#%d rnr nak timer fired\n", qp_num(qp)); >>> +    qp->req.need_retry = 1; >>> +    qp->req.need_rnr_timeout = 0; >>>       rxe_run_task(&qp->req.task, 1); >>>   } >>> @@ -624,10 +625,11 @@ int rxe_requester(void *arg) >>>           qp->req.need_rd_atomic = 0; >>>           qp->req.wait_psn = 0; >>>           qp->req.need_retry = 0; >>> +        qp->req.need_rnr_timeout = 0; >>>           goto exit; >>>       } >>> -    if (unlikely(qp->req.need_retry)) { >>> +    if (unlikely(qp->req.need_retry && !qp->req.need_rnr_timeout)) { >>>           req_retry(qp); >>>           qp->req.need_retry = 0; >>>       } >>> diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.h b/drivers/infiniband/sw/rxe/rxe_verbs.h >>> index e7eff1ca75e9..ab3186478c3f 100644 >>> --- a/drivers/infiniband/sw/rxe/rxe_verbs.h >>> +++ b/drivers/infiniband/sw/rxe/rxe_verbs.h >>> @@ -123,6 +123,7 @@ struct rxe_req_info { >>>       int            need_rd_atomic; >>>       int            wait_psn; >>>       int            need_retry; >>> +    int            need_rnr_timeout; >>>       int            noack_pkts; >>>       struct rxe_task        task; >>>   }; >>> >>> base-commit: c5eb0a61238dd6faf37f58c9ce61c9980aaffd7a >>