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[73.158.218.242]) by smtp.gmail.com with UTF8SMTPSA id d9443c01a7336-23acb3b8409sm139504355ad.184.2025.07.02.09.03.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Jul 2025 09:03:01 -0700 (PDT) Date: Wed, 2 Jul 2025 09:03:00 -0700 From: Stanislav Fomichev To: Jason Xing Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, bjorn@kernel.org, magnus.karlsson@intel.com, maciej.fijalkowski@intel.com, jonathan.lemon@gmail.com, sdf@fomichev.me, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, joe@dama.to, willemdebruijn.kernel@gmail.com, bpf@vger.kernel.org, netdev@vger.kernel.org, Jason Xing Subject: Re: [PATCH net-next v5 2/2] selftests/bpf: add a new test to check the consumer update case Message-ID: References: <20250702112815.50746-1-kerneljasonxing@gmail.com> <20250702112815.50746-3-kerneljasonxing@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250702112815.50746-3-kerneljasonxing@gmail.com> On 07/02, Jason Xing wrote: > From: Jason Xing > > The subtest sends 33 packets at one time on purpose to see if xsk > exitting __xsk_generic_xmit() updates the global consumer of tx queue > when reaching the max loop (max_tx_budget, 32 by default). The number 33 > can avoid xskq_cons_peek_desc() updates the consumer when it's about to > quit sending, to accurately check if the issue that the first patch > resolves remains. The new case will not check this issue in zero copy > mode. > > Signed-off-by: Jason Xing > --- > v5 > Link: https://lore.kernel.org/all/20250627085745.53173-1-kerneljasonxing@gmail.com/ > 1. use the initial approach to add a new testcase > 2. add a new flag 'check_consumer' to see if the check is needed > --- > tools/testing/selftests/bpf/xskxceiver.c | 51 +++++++++++++++++++++++- > tools/testing/selftests/bpf/xskxceiver.h | 1 + > 2 files changed, 51 insertions(+), 1 deletion(-) > > diff --git a/tools/testing/selftests/bpf/xskxceiver.c b/tools/testing/selftests/bpf/xskxceiver.c > index 0ced4026ee44..ed12a55ecf2a 100644 > --- a/tools/testing/selftests/bpf/xskxceiver.c > +++ b/tools/testing/selftests/bpf/xskxceiver.c > @@ -109,6 +109,8 @@ > > #include > > +#define MAX_TX_BUDGET_DEFAULT 32 > + > static bool opt_verbose; > static bool opt_print_tests; > static enum test_mode opt_mode = TEST_MODE_ALL; > @@ -1091,11 +1093,45 @@ static bool is_pkt_valid(struct pkt *pkt, void *buffer, u64 addr, u32 len) > return true; > } > > +static u32 load_value(u32 *counter) > +{ > + return __atomic_load_n(counter, __ATOMIC_ACQUIRE); > +} > + > +static bool kick_tx_with_check(struct xsk_socket_info *xsk, int *ret) > +{ > + u32 max_budget = MAX_TX_BUDGET_DEFAULT; > + u32 cons, ready_to_send; > + int delta; > + > + cons = load_value(xsk->tx.consumer); > + ready_to_send = load_value(xsk->tx.producer) - cons; > + *ret = sendto(xsk_socket__fd(xsk->xsk), NULL, 0, MSG_DONTWAIT, NULL, 0); > + > + delta = load_value(xsk->tx.consumer) - cons; > + /* By default, xsk should consume exact @max_budget descs at one > + * send in this case where hitting the max budget limit in while > + * loop is triggered in __xsk_generic_xmit(). Please make sure that > + * the number of descs to be sent is larger than @max_budget, or > + * else the tx.consumer will be updated in xskq_cons_peek_desc() > + * in time which hides the issue we try to verify. > + */ > + if (ready_to_send > max_budget && delta != max_budget) > + return false; > + > + return true; > +} > + > static int kick_tx(struct xsk_socket_info *xsk) > { > int ret; > > - ret = sendto(xsk_socket__fd(xsk->xsk), NULL, 0, MSG_DONTWAIT, NULL, 0); > + if (xsk->check_consumer) { > + if (!kick_tx_with_check(xsk, &ret)) > + return TEST_FAILURE; > + } else { > + ret = sendto(xsk_socket__fd(xsk->xsk), NULL, 0, MSG_DONTWAIT, NULL, 0); > + } > if (ret >= 0) > return TEST_PASS; > if (errno == ENOBUFS || errno == EAGAIN || errno == EBUSY || errno == ENETDOWN) { > @@ -2613,6 +2649,18 @@ static int testapp_adjust_tail_grow_mb(struct test_spec *test) > XSK_UMEM__LARGE_FRAME_SIZE * 2); > } > > +static int testapp_tx_queue_consumer(struct test_spec *test) > +{ > + int nr_packets = MAX_TX_BUDGET_DEFAULT + 1; > + > + pkt_stream_replace(test, nr_packets, MIN_PKT_SIZE); > + test->ifobj_tx->xsk->batch_size = nr_packets; > + if (!(test->mode & TEST_MODE_ZC)) > + test->ifobj_tx->xsk->check_consumer = true; The test looks good to me, thank you! One question here: why not exit/return for TEST_MODE_ZC instead of conditionally setting check_consumer?