Hello, Thanks for the reviews.
On 5/19/2026 11:57 AM, Mathieu Poirier wrote: > Hi Tanmay > > (Apologies for the late review) > No problem. > On Wed, Apr 29, 2026 at 09:10:51AM -0700, Tanmay Shah wrote: >> Current design allocates memory for tx and rx buffers equally. The >> throughput can be increased if the user is allowed to configure number >> of tx and rx buffers as required. Hence, do not split number of tx & rx >> buffers into half, but decide based on respective vring size. >> >> Signed-off-by: Tanmay Shah <[email protected]> >> --- >> >> Test performed: >> - Test this patch with existing firmware as it is, rpmsg working. >> >> Changes in v2: >> - Change author >> - fix commit message with better explanation >> - %s/sbuf/tx_buf >> - %s/rbuf/rx_buf >> - %s/num_rbuf/num_rx_buf/ >> - %s/num_sbuf/num_tx_buf/ > > Please split this patch in two parts - one to do the refactoring of the > tx/rx_buf and another one for the varying size. Ack. > >> >> drivers/rpmsg/virtio_rpmsg_bus.c | 68 ++++++++++++++++---------------- >> 1 file changed, 34 insertions(+), 34 deletions(-) >> >> diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c >> b/drivers/rpmsg/virtio_rpmsg_bus.c >> index 5ae15111fb4f..e59d8cf9b975 100644 >> --- a/drivers/rpmsg/virtio_rpmsg_bus.c >> +++ b/drivers/rpmsg/virtio_rpmsg_bus.c >> @@ -35,13 +35,14 @@ >> * @vdev: the virtio device >> * @rvq: rx virtqueue >> * @svq: tx virtqueue >> - * @rbufs: kernel address of rx buffers >> - * @sbufs: kernel address of tx buffers >> - * @num_bufs: total number of buffers for rx and tx >> - * @buf_size: size of one rx or tx buffer >> + * @rx_bufs: kernel address of rx buffers >> + * @tx_bufs: kernel address of tx buffers >> + * @num_rx_buf: total number of buffers for rx >> + * @num_tx_buf: total number of buffers for tx >> + * @buf_size: size of one rx or tx buffer >> * @last_sbuf: index of last tx buffer used >> * @bufs_dma: dma base addr of the buffers >> - * @tx_lock: protects svq and sbufs, to allow concurrent senders. >> + * @tx_lock: protects svq and tx_bufs, to allow concurrent senders. >> * sending a message might require waking up a dozing remote >> * processor, which involves sleeping, hence the mutex. >> * @endpoints: idr of local endpoints, allows fast retrieval >> @@ -55,8 +56,9 @@ >> struct virtproc_info { >> struct virtio_device *vdev; >> struct virtqueue *rvq, *svq; >> - void *rbufs, *sbufs; >> - unsigned int num_bufs; >> + void *rx_bufs, *tx_bufs; >> + unsigned int num_rx_buf; >> + unsigned int num_tx_buf; >> unsigned int buf_size; >> int last_sbuf; >> dma_addr_t bufs_dma; >> @@ -110,7 +112,7 @@ struct virtio_rpmsg_channel { >> /* >> * We're allocating buffers of 512 bytes each for communications. The >> * number of buffers will be computed from the number of buffers supported >> - * by the vring, upto a maximum of 512 buffers (256 in each direction). >> + * by the vring, up to a maximum of 256 in each direction. >> * >> * Each buffer will have 16 bytes for the msg header and 496 bytes for >> * the payload. >> @@ -125,7 +127,7 @@ struct virtio_rpmsg_channel { >> * can change this without changing anything in the firmware of the remote >> * processor. >> */ >> -#define MAX_RPMSG_NUM_BUFS (512) >> +#define MAX_RPMSG_NUM_BUFS (256) >> #define MAX_RPMSG_BUF_SIZE (512) >> >> /* >> @@ -440,12 +442,9 @@ static void *get_a_tx_buf(struct virtproc_info *vrp) >> >> mutex_lock(&vrp->tx_lock); >> >> - /* >> - * either pick the next unused tx buffer >> - * (half of our buffers are used for sending messages) >> - */ >> - if (vrp->last_sbuf < vrp->num_bufs / 2) >> - ret = vrp->sbufs + vrp->buf_size * vrp->last_sbuf++; >> + /* either pick the next unused tx buffer */ >> + if (vrp->last_sbuf < vrp->num_tx_buf) >> + ret = vrp->tx_bufs + vrp->buf_size * vrp->last_sbuf++; >> /* or recycle a used one */ >> else >> ret = virtqueue_get_buf(vrp->svq, &len); >> @@ -631,11 +630,10 @@ static __poll_t virtio_rpmsg_poll(struct >> rpmsg_endpoint *ept, struct file *filp, >> >> /* >> * check for a free buffer, either: >> - * - we haven't used all of the available transmit buffers (half of the >> - * allocated buffers are used for transmit, hence num_bufs / 2), or, >> + * - we haven't used all of the available transmit buffers or, >> * - we ask the virtqueue if there's a buffer available >> */ >> - if (vrp->last_sbuf < vrp->num_bufs / 2 || >> + if (vrp->last_sbuf < vrp->num_tx_buf || >> !virtqueue_enable_cb(vrp->svq)) >> mask |= EPOLLOUT; >> >> @@ -846,19 +844,20 @@ static int rpmsg_probe(struct virtio_device *vdev) >> vrp->rvq = vqs[0]; >> vrp->svq = vqs[1]; >> >> - /* we expect symmetric tx/rx vrings */ >> - WARN_ON(virtqueue_get_vring_size(vrp->rvq) != >> - virtqueue_get_vring_size(vrp->svq)); >> - >> /* we need less buffers if vrings are small */ >> - if (virtqueue_get_vring_size(vrp->rvq) < MAX_RPMSG_NUM_BUFS / 2) >> - vrp->num_bufs = virtqueue_get_vring_size(vrp->rvq) * 2; >> + if (virtqueue_get_vring_size(vrp->rvq) < MAX_RPMSG_NUM_BUFS) >> + vrp->num_rx_buf = virtqueue_get_vring_size(vrp->rvq); >> + else >> + vrp->num_rx_buf = MAX_RPMSG_NUM_BUFS; >> + >> + if (virtqueue_get_vring_size(vrp->svq) < MAX_RPMSG_NUM_BUFS) >> + vrp->num_tx_buf = virtqueue_get_vring_size(vrp->svq); >> else >> - vrp->num_bufs = MAX_RPMSG_NUM_BUFS; >> + vrp->num_tx_buf = MAX_RPMSG_NUM_BUFS; >> >> vrp->buf_size = MAX_RPMSG_BUF_SIZE; >> >> - total_buf_space = vrp->num_bufs * vrp->buf_size; >> + total_buf_space = (vrp->num_rx_buf + vrp->num_tx_buf) * vrp->buf_size; >> >> /* allocate coherent memory for the buffers */ >> bufs_va = dma_alloc_coherent(vdev->dev.parent, >> @@ -872,16 +871,16 @@ static int rpmsg_probe(struct virtio_device *vdev) >> dev_dbg(&vdev->dev, "buffers: va %p, dma %pad\n", >> bufs_va, &vrp->bufs_dma); >> >> - /* half of the buffers is dedicated for RX */ >> - vrp->rbufs = bufs_va; >> + /* first part of the buffers is dedicated for RX */ >> + vrp->rx_bufs = bufs_va; >> >> - /* and half is dedicated for TX */ >> - vrp->sbufs = bufs_va + total_buf_space / 2; >> + /* and second part is dedicated for TX */ >> + vrp->tx_bufs = bufs_va + vrp->num_rx_buf * vrp->buf_size; >> >> /* set up the receive buffers */ >> - for (i = 0; i < vrp->num_bufs / 2; i++) { >> + for (i = 0; i < vrp->num_rx_buf; i++) { >> struct scatterlist sg; >> - void *cpu_addr = vrp->rbufs + i * vrp->buf_size; >> + void *cpu_addr = vrp->rx_bufs + i * vrp->buf_size; >> >> rpmsg_sg_init(&sg, cpu_addr, vrp->buf_size); >> >> @@ -966,7 +965,8 @@ static int rpmsg_remove_device(struct device *dev, void >> *data) >> static void rpmsg_remove(struct virtio_device *vdev) >> { >> struct virtproc_info *vrp = vdev->priv; >> - size_t total_buf_space = vrp->num_bufs * vrp->buf_size; >> + unsigned int num_bufs = vrp->num_rx_buf + vrp->num_tx_buf; >> + size_t total_buf_space = num_bufs * vrp->buf_size; >> int ret; >> >> virtio_reset_device(vdev); >> @@ -980,7 +980,7 @@ static void rpmsg_remove(struct virtio_device *vdev) >> vdev->config->del_vqs(vrp->vdev); >> >> dma_free_coherent(vdev->dev.parent, total_buf_space, >> - vrp->rbufs, vrp->bufs_dma); >> + vrp->rx_bufs, vrp->bufs_dma); >> >> kfree(vrp); >> } >> -- >> 2.34.1 >>
