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[73.158.218.242]) by smtp.gmail.com with UTF8SMTPSA id d2e1a72fcca58-742a982b7e8sm10220305b3a.90.2025.05.21.10.39.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 May 2025 10:39:00 -0700 (PDT) Date: Wed, 21 May 2025 10:39:00 -0700 From: Stanislav Fomichev To: Mina Almasry Cc: netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, viro@zeniv.linux.org.uk, horms@kernel.org, andrew+netdev@lunn.ch, shuah@kernel.org, sagi@grimberg.me, willemb@google.com, asml.silence@gmail.com, jdamato@fastly.com, kaiyuanz@google.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH net-next 2/3] selftests: ncdevmem: make chunking optional Message-ID: References: <20250520203044.2689904-1-stfomichev@gmail.com> <20250520203044.2689904-2-stfomichev@gmail.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On 05/21, Mina Almasry wrote: > On Tue, May 20, 2025 at 1:30 PM Stanislav Fomichev wrote: > > > > Add new -z argument to specify max IOV size. By default, use > > single large IOV. > > > > Signed-off-by: Stanislav Fomichev > > --- > > .../selftests/drivers/net/hw/ncdevmem.c | 49 +++++++++++-------- > > 1 file changed, 29 insertions(+), 20 deletions(-) > > > > diff --git a/tools/testing/selftests/drivers/net/hw/ncdevmem.c b/tools/testing/selftests/drivers/net/hw/ncdevmem.c > > index ca723722a810..fc7ba7d71502 100644 > > --- a/tools/testing/selftests/drivers/net/hw/ncdevmem.c > > +++ b/tools/testing/selftests/drivers/net/hw/ncdevmem.c > > @@ -82,6 +82,9 @@ > > #define MSG_SOCK_DEVMEM 0x2000000 > > #endif > > > > +#define MAX_IOV 1024 > > + > > +static size_t max_chunk; > > static char *server_ip; > > static char *client_ip; > > static char *port; > > @@ -834,10 +837,10 @@ static int do_client(struct memory_buffer *mem) > > struct sockaddr_in6 server_sin; > > struct sockaddr_in6 client_sin; > > struct ynl_sock *ys = NULL; > > + struct iovec iov[MAX_IOV]; > > struct msghdr msg = {}; > > ssize_t line_size = 0; > > struct cmsghdr *cmsg; > > - struct iovec iov[2]; > > char *line = NULL; > > unsigned long mid; > > size_t len = 0; > > @@ -893,27 +896,29 @@ static int do_client(struct memory_buffer *mem) > > if (line_size < 0) > > break; > > > > - mid = (line_size / 2) + 1; > > - > > - iov[0].iov_base = (void *)1; > > - iov[0].iov_len = mid; > > - iov[1].iov_base = (void *)(mid + 2); > > - iov[1].iov_len = line_size - mid; > > + if (max_chunk) { > > + msg.msg_iovlen = > > + (line_size + max_chunk - 1) / max_chunk; > > + if (msg.msg_iovlen > MAX_IOV) > > + error(1, 0, > > + "can't partition %zd bytes into maximum of %d chunks", > > + line_size, MAX_IOV); > > > > - provider->memcpy_to_device(mem, (size_t)iov[0].iov_base, line, > > - iov[0].iov_len); > > - provider->memcpy_to_device(mem, (size_t)iov[1].iov_base, > > - line + iov[0].iov_len, > > - iov[1].iov_len); > > + for (int i = 0; i < msg.msg_iovlen; i++) { > > + iov[i].iov_base = (void *)(i * max_chunk); > > + iov[i].iov_len = max_chunk; > > Isn't the last iov going to be truncated in the case where line_size > is not exactly divisible with max_chunk? I have this for the last iov entry: iov[msg.msg_iovlen - 1].iov_len = line_size - (msg.msg_iovlen - 1) * max_chunk; I think that should correctly adjust it to the remaining 1..max_chunk len? > > + } > > > > - fprintf(stderr, > > - "read line_size=%ld iov[0].iov_base=%lu, iov[0].iov_len=%lu, iov[1].iov_base=%lu, iov[1].iov_len=%lu\n", > > - line_size, (unsigned long)iov[0].iov_base, > > - iov[0].iov_len, (unsigned long)iov[1].iov_base, > > - iov[1].iov_len); > > + iov[msg.msg_iovlen - 1].iov_len = > > + line_size - (msg.msg_iovlen - 1) * max_chunk; > > + } else { > > + iov[0].iov_base = 0; > > + iov[0].iov_len = line_size; > > + msg.msg_iovlen = 1; > > + } > > Do you need to special case this? Shouldn't this be the same as max_chunk==1? I might need a better name. max_chunk is the max size of the iov entry (max iov_len), not the max number of IOVs. And I use max_chunk==0 as "max size of the iov is not provided -> use line_size", so not sure I can't make it work without a special case?