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[176.103.220.4]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4856ea8fb0dsm43255905e9.3.2026.03.16.17.02.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Mar 2026 17:02:28 -0700 (PDT) From: Stefano Brivio To: Laurent Vivier Subject: Re: [PATCH v2 2/3] vu_handle_tx: Pass actual remaining out_sg capacity to vu_queue_pop() Message-ID: <20260317010227.565ffb1c@elisabeth> In-Reply-To: <20260313182618.4157365-3-lvivier@redhat.com> References: <20260313182618.4157365-1-lvivier@redhat.com> <20260313182618.4157365-3-lvivier@redhat.com> Organization: Red Hat X-Mailer: Claws Mail 4.2.0 (GTK 3.24.49; x86_64-pc-linux-gnu) MIME-Version: 1.0 Date: Tue, 17 Mar 2026 01:02:27 +0100 (CET) X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: CBrLoTXpH0LDSqToyQdNr2lozepY0MF0IiFb9WfJ9IQ_1773705750 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-ID-Hash: J5ZV5WMU6OOYT4H6MUMJNVDIRNL4Q3OR X-Message-ID-Hash: J5ZV5WMU6OOYT4H6MUMJNVDIRNL4Q3OR X-MailFrom: sbrivio@redhat.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: passt-dev@passt.top X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Fri, 13 Mar 2026 19:26:17 +0100 Laurent Vivier wrote: > In vu_handle_tx(), pass the actual remaining iovec capacity > (ARRAY_SIZE(out_sg) - out_sg_count) to vu_queue_pop() rather than a > fixed VU_MAX_TX_BUFFER_NB. > > This enables dynamic allocation of iovec entries to each element rather > than reserving a fixed number of slots per descriptor. > > Signed-off-by: Laurent Vivier > --- > vu_common.c | 11 +++++------ > 1 file changed, 5 insertions(+), 6 deletions(-) > > diff --git a/vu_common.c b/vu_common.c > index 4d809ac38a4b..ed0033d6bb11 100644 > --- a/vu_common.c > +++ b/vu_common.c > @@ -20,8 +20,6 @@ > #include "migrate.h" > #include "epoll_ctl.h" > > -#define VU_MAX_TX_BUFFER_NB 2 > - > /** > * vu_packet_check_range() - Check if a given memory zone is contained in > * a mapped guest memory region > @@ -177,13 +175,14 @@ static void vu_handle_tx(struct vu_dev *vdev, int index, > > count = 0; > out_sg_count = 0; > - while (count < VIRTQUEUE_MAX_SIZE && > - out_sg_count + VU_MAX_TX_BUFFER_NB <= VIRTQUEUE_MAX_SIZE) { > - int ret; > + while (count < ARRAY_SIZE(elem) && > + out_sg_count < ARRAY_SIZE(out_sg)) { Nit: you could do this now: while (count < ARRAY_SIZE(elem) && out_sg_count < ARRAY_SIZE(out_sg)) { I still need a bit of time to review 3/3, if you don't need to re-spin for other reasons I can also fix this up on merge. > struct iov_tail data; > + int ret; > > ret = vu_queue_pop(vdev, vq, &elem[count], NULL, 0, > - &out_sg[out_sg_count], VU_MAX_TX_BUFFER_NB); > + &out_sg[out_sg_count], > + ARRAY_SIZE(out_sg) - out_sg_count); > if (ret < 0) > break; > out_sg_count += elem[count].out_num; -- Stefano