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Message-ID: <ba2643d8-d312-4adf-9672-d4525bd9dc91@ti.com>
Date: Mon, 3 Mar 2025 16:46:31 +0530
From: "Malladi, Meghana" <m-malladi@...com>
To: Roger Quadros <rogerq@...nel.org>, <danishanwar@...com>,
<pabeni@...hat.com>, <kuba@...nel.org>, <edumazet@...gle.com>,
<davem@...emloft.net>, <andrew+netdev@...n.ch>
CC: <bpf@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
<u.kleine-koenig@...libre.com>, <matthias.schiffer@...tq-group.com>,
<dan.carpenter@...aro.org>, <schnelle@...ux.ibm.com>,
<diogo.ivo@...mens.com>, <glaroque@...libre.com>, <macro@...am.me.uk>,
<john.fastabend@...il.com>, <hawk@...nel.org>, <daniel@...earbox.net>,
<ast@...nel.org>, <srk@...com>, Vignesh Raghavendra <vigneshr@...com>
Subject: Re: [PATCH net-next v3 1/3] net: ti: icssg-prueth: Use page_pool API
for RX buffer allocation
Hi Roger,
On 2/24/2025 7:50 PM, Roger Quadros wrote:
>
>
> On 24/02/2025 13:01, Meghana Malladi wrote:
>> From: Roger Quadros <rogerq@...nel.org>
>>
>> This is to prepare for native XDP support.
>>
>> The page pool API is more faster in allocating pages than
>> __alloc_skb(). Drawback is that it works at PAGE_SIZE granularity
>> so we are not efficient in memory usage.
>> i.e. we are using PAGE_SIZE (4KB) memory for 1.5KB max packet size.
>>
>> Signed-off-by: Roger Quadros <rogerq@...nel.org>
>> Signed-off-by: MD Danish Anwar <danishanwar@...com>
>> Signed-off-by: Meghana Malladi <m-malladi@...com>
>> ---
>> Changes since v2 (v3-v2):
>> - few cosmetic changes for all the patches as suggested by
>> Roger Quadros <rogerq@...nel.org>
>>
>> drivers/net/ethernet/ti/Kconfig | 1 +
>> drivers/net/ethernet/ti/icssg/icssg_common.c | 174 ++++++++++++------
>> drivers/net/ethernet/ti/icssg/icssg_prueth.h | 14 +-
>> .../net/ethernet/ti/icssg/icssg_prueth_sr1.c | 21 ++-
>> 4 files changed, 139 insertions(+), 71 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/ti/Kconfig b/drivers/net/ethernet/ti/Kconfig
>> index 0d5a862cd78a..b461281d31b6 100644
>> --- a/drivers/net/ethernet/ti/Kconfig
>> +++ b/drivers/net/ethernet/ti/Kconfig
>> @@ -204,6 +204,7 @@ config TI_ICSSG_PRUETH_SR1
>> select PHYLIB
>> select TI_ICSS_IEP
>> select TI_K3_CPPI_DESC_POOL
>> + select PAGE_POOL
>> depends on PRU_REMOTEPROC
>> depends on NET_SWITCHDEV
>> depends on ARCH_K3 && OF && TI_K3_UDMA_GLUE_LAYER
>> diff --git a/drivers/net/ethernet/ti/icssg/icssg_common.c b/drivers/net/ethernet/ti/icssg/icssg_common.c
>> index 74f0f200a89d..acbb79ad8b0c 100644
>> --- a/drivers/net/ethernet/ti/icssg/icssg_common.c
>> +++ b/drivers/net/ethernet/ti/icssg/icssg_common.c
>> @@ -45,6 +45,11 @@ void prueth_cleanup_rx_chns(struct prueth_emac *emac,
>> struct prueth_rx_chn *rx_chn,
>> int max_rflows)
>> {
>> + if (rx_chn->pg_pool) {
>> + page_pool_destroy(rx_chn->pg_pool);
>> + rx_chn->pg_pool = NULL;
>> + }
>> +
>> if (rx_chn->desc_pool)
>> k3_cppi_desc_pool_destroy(rx_chn->desc_pool);
>>
>> @@ -461,17 +466,17 @@ int prueth_init_rx_chns(struct prueth_emac *emac,
>> }
>> EXPORT_SYMBOL_GPL(prueth_init_rx_chns);
>>
>> -int prueth_dma_rx_push(struct prueth_emac *emac,
>> - struct sk_buff *skb,
>> - struct prueth_rx_chn *rx_chn)
>> +int prueth_dma_rx_push_mapped(struct prueth_emac *emac,
>> + struct prueth_rx_chn *rx_chn,
>> + struct page *page, u32 buf_len)
>> {
>> struct net_device *ndev = emac->ndev;
>> struct cppi5_host_desc_t *desc_rx;
>> - u32 pkt_len = skb_tailroom(skb);
>> dma_addr_t desc_dma;
>> dma_addr_t buf_dma;
>> void **swdata;
>>
>> + buf_dma = page_pool_get_dma_addr(page) + PRUETH_HEADROOM;
>> desc_rx = k3_cppi_desc_pool_alloc(rx_chn->desc_pool);
>> if (!desc_rx) {
>> netdev_err(ndev, "rx push: failed to allocate descriptor\n");
>> @@ -479,25 +484,18 @@ int prueth_dma_rx_push(struct prueth_emac *emac,
>> }
>> desc_dma = k3_cppi_desc_pool_virt2dma(rx_chn->desc_pool, desc_rx);
>>
>> - buf_dma = dma_map_single(rx_chn->dma_dev, skb->data, pkt_len, DMA_FROM_DEVICE);
>> - if (unlikely(dma_mapping_error(rx_chn->dma_dev, buf_dma))) {
>> - k3_cppi_desc_pool_free(rx_chn->desc_pool, desc_rx);
>> - netdev_err(ndev, "rx push: failed to map rx pkt buffer\n");
>> - return -EINVAL;
>> - }
>> -
>> cppi5_hdesc_init(desc_rx, CPPI5_INFO0_HDESC_EPIB_PRESENT,
>> PRUETH_NAV_PS_DATA_SIZE);
>> k3_udma_glue_rx_dma_to_cppi5_addr(rx_chn->rx_chn, &buf_dma);
>> - cppi5_hdesc_attach_buf(desc_rx, buf_dma, skb_tailroom(skb), buf_dma, skb_tailroom(skb));
>> + cppi5_hdesc_attach_buf(desc_rx, buf_dma, buf_len, buf_dma, buf_len);
>>
>> swdata = cppi5_hdesc_get_swdata(desc_rx);
>> - *swdata = skb;
>> + *swdata = page;
>>
>> - return k3_udma_glue_push_rx_chn(rx_chn->rx_chn, 0,
>> + return k3_udma_glue_push_rx_chn(rx_chn->rx_chn, PRUETH_RX_FLOW_DATA,
>> desc_rx, desc_dma);
>> }
>> -EXPORT_SYMBOL_GPL(prueth_dma_rx_push);
>> +EXPORT_SYMBOL_GPL(prueth_dma_rx_push_mapped);
>>
>> u64 icssg_ts_to_ns(u32 hi_sw, u32 hi, u32 lo, u32 cycle_time_ns)
>> {
>> @@ -541,12 +539,16 @@ static int emac_rx_packet(struct prueth_emac *emac, u32 flow_id)
>> u32 buf_dma_len, pkt_len, port_id = 0;
>> struct net_device *ndev = emac->ndev;
>> struct cppi5_host_desc_t *desc_rx;
>> - struct sk_buff *skb, *new_skb;
>> dma_addr_t desc_dma, buf_dma;
>> + struct page *page, *new_page;
>> + struct page_pool *pool;
>> + struct sk_buff *skb;
>> void **swdata;
>> u32 *psdata;
>> + void *pa;
>> int ret;
>>
>> + pool = rx_chn->pg_pool;
>> ret = k3_udma_glue_pop_rx_chn(rx_chn->rx_chn, flow_id, &desc_dma);
>> if (ret) {
>> if (ret != -ENODATA)
>> @@ -558,15 +560,9 @@ static int emac_rx_packet(struct prueth_emac *emac, u32 flow_id)
>> return 0;
>>
>> desc_rx = k3_cppi_desc_pool_dma2virt(rx_chn->desc_pool, desc_dma);
>> -
>> swdata = cppi5_hdesc_get_swdata(desc_rx);
>> - skb = *swdata;
>> -
>> - psdata = cppi5_hdesc_get_psdata(desc_rx);
>> - /* RX HW timestamp */
>> - if (emac->rx_ts_enabled)
>> - emac_rx_timestamp(emac, skb, psdata);
>> -
>> + page = *swdata;
>> + page_pool_dma_sync_for_cpu(pool, page, 0, PAGE_SIZE);
>> cppi5_hdesc_get_obuf(desc_rx, &buf_dma, &buf_dma_len);
>> k3_udma_glue_rx_cppi5_to_dma_addr(rx_chn->rx_chn, &buf_dma);
>> pkt_len = cppi5_hdesc_get_pktlen(desc_rx);
>> @@ -574,32 +570,51 @@ static int emac_rx_packet(struct prueth_emac *emac, u32 flow_id)
>> pkt_len -= 4;
>> cppi5_desc_get_tags_ids(&desc_rx->hdr, &port_id, NULL);
>>
>> - dma_unmap_single(rx_chn->dma_dev, buf_dma, buf_dma_len, DMA_FROM_DEVICE);
>> k3_cppi_desc_pool_free(rx_chn->desc_pool, desc_rx);
>>
>> - skb->dev = ndev;
>> - new_skb = netdev_alloc_skb_ip_align(ndev, PRUETH_MAX_PKT_SIZE);
>> /* if allocation fails we drop the packet but push the
>> - * descriptor back to the ring with old skb to prevent a stall
>> + * descriptor back to the ring with old page to prevent a stall
>> */
>> - if (!new_skb) {
>> + new_page = page_pool_dev_alloc_pages(pool);
>> + if (unlikely(!new_page)) {
>> + new_page = page;
>> ndev->stats.rx_dropped++;
>> - new_skb = skb;
>> - } else {
>> - /* send the filled skb up the n/w stack */
>> - skb_put(skb, pkt_len);
>> - if (emac->prueth->is_switch_mode)
>> - skb->offload_fwd_mark = emac->offload_fwd_mark;
>> - skb->protocol = eth_type_trans(skb, ndev);
>> - napi_gro_receive(&emac->napi_rx, skb);
>> - ndev->stats.rx_bytes += pkt_len;
>> - ndev->stats.rx_packets++;
>> + goto requeue;
>> + }
>> +
>> + /* prepare skb and send to n/w stack */
>> + pa = page_address(page);
>> + skb = napi_build_skb(pa, PAGE_SIZE);
>> + if (!skb) {
>> + ndev->stats.rx_dropped++;
>> + page_pool_recycle_direct(pool, page);
>> + goto requeue;
>> }
>>
>> + skb_reserve(skb, PRUETH_HEADROOM);
>> + skb_put(skb, pkt_len);
>> + skb->dev = ndev;
>> +
>> + psdata = cppi5_hdesc_get_psdata(desc_rx);
>> + /* RX HW timestamp */
>> + if (emac->rx_ts_enabled)
>> + emac_rx_timestamp(emac, skb, psdata);
>> +
>> + if (emac->prueth->is_switch_mode)
>> + skb->offload_fwd_mark = emac->offload_fwd_mark;
>> + skb->protocol = eth_type_trans(skb, ndev);
>> +
>> + skb_mark_for_recycle(skb);
>> + napi_gro_receive(&emac->napi_rx, skb);
>> + ndev->stats.rx_bytes += pkt_len;
>> + ndev->stats.rx_packets++;
>> +
>> +requeue:
>> /* queue another RX DMA */
>> - ret = prueth_dma_rx_push(emac, new_skb, &emac->rx_chns);
>> + ret = prueth_dma_rx_push_mapped(emac, &emac->rx_chns, new_page,
>> + PRUETH_MAX_PKT_SIZE);
>> if (WARN_ON(ret < 0)) {
>> - dev_kfree_skb_any(new_skb);
>> + page_pool_recycle_direct(pool, new_page);
>> ndev->stats.rx_errors++;
>> ndev->stats.rx_dropped++;
>> }
>> @@ -611,22 +626,16 @@ static void prueth_rx_cleanup(void *data, dma_addr_t desc_dma)
>> {
>> struct prueth_rx_chn *rx_chn = data;
>> struct cppi5_host_desc_t *desc_rx;
>> - struct sk_buff *skb;
>> - dma_addr_t buf_dma;
>> - u32 buf_dma_len;
>> + struct page_pool *pool;
>> + struct page *page;
>> void **swdata;
>>
>> + pool = rx_chn->pg_pool;
>> desc_rx = k3_cppi_desc_pool_dma2virt(rx_chn->desc_pool, desc_dma);
>> swdata = cppi5_hdesc_get_swdata(desc_rx);
>> - skb = *swdata;
>> - cppi5_hdesc_get_obuf(desc_rx, &buf_dma, &buf_dma_len);
>> - k3_udma_glue_rx_cppi5_to_dma_addr(rx_chn->rx_chn, &buf_dma);
>> -
>> - dma_unmap_single(rx_chn->dma_dev, buf_dma, buf_dma_len,
>> - DMA_FROM_DEVICE);
>> + page = *swdata;
>> + page_pool_recycle_direct(pool, page);
>> k3_cppi_desc_pool_free(rx_chn->desc_pool, desc_rx);
>> -
>> - dev_kfree_skb_any(skb);
>> }
>>
>> static int prueth_tx_ts_cookie_get(struct prueth_emac *emac)
>> @@ -907,29 +916,71 @@ int icssg_napi_rx_poll(struct napi_struct *napi_rx, int budget)
>> }
>> EXPORT_SYMBOL_GPL(icssg_napi_rx_poll);
>>
>> +static struct page_pool *prueth_create_page_pool(struct prueth_emac *emac,
>> + struct device *dma_dev,
>> + int size)
>> +{
>> + struct page_pool_params pp_params = { 0 };
>> + struct page_pool *pool;
>> +
>> + pp_params.order = 0;
>> + pp_params.flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV;
>> + pp_params.pool_size = size;
>> + pp_params.nid = dev_to_node(emac->prueth->dev);
>> + pp_params.dma_dir = DMA_BIDIRECTIONAL;
>> + pp_params.dev = dma_dev;
>> + pp_params.napi = &emac->napi_rx;
>> + pp_params.max_len = PAGE_SIZE;
>> +
>> + pool = page_pool_create(&pp_params);
>> + if (IS_ERR(pool))
>> + netdev_err(emac->ndev, "cannot create rx page pool\n");
>> +
>> + return pool;
>> +}
>> +
>> int prueth_prepare_rx_chan(struct prueth_emac *emac,
>> struct prueth_rx_chn *chn,
>> int buf_size)
>> {
>> - struct sk_buff *skb;
>> + struct page_pool *pool;
>> + struct page *page;
>> int i, ret;
>>
>> + pool = prueth_create_page_pool(emac, chn->dma_dev, chn->descs_num);
>> + if (IS_ERR(pool))
>> + return PTR_ERR(pool);
>> +
>> + chn->pg_pool = pool;
>> +
>> for (i = 0; i < chn->descs_num; i++) {
>> - skb = __netdev_alloc_skb_ip_align(NULL, buf_size, GFP_KERNEL);
>> - if (!skb)
>> - return -ENOMEM;
>> + /* NOTE: we're not using memory efficiently here.
>> + * 1 full page (4KB?) used here instead of
>> + * PRUETH_MAX_PKT_SIZE (~1.5KB?)
>> + */
>> + page = page_pool_dev_alloc_pages(pool);
>> + if (!page) {
>> + netdev_err(emac->ndev, "couldn't allocate rx page\n");
>> + ret = -ENOMEM;
>> + goto recycle_alloc_pg;
>> + }
>>
>> - ret = prueth_dma_rx_push(emac, skb, chn);
>> + ret = prueth_dma_rx_push_mapped(emac, chn, page, buf_size);
>> if (ret < 0) {
>> netdev_err(emac->ndev,
>> - "cannot submit skb for rx chan %s ret %d\n",
>> + "cannot submit page for rx chan %s ret %d\n",
>> chn->name, ret);
>> - kfree_skb(skb);
>> - return ret;
>> + page_pool_recycle_direct(pool, page);
>> + goto recycle_alloc_pg;
>> }
>> }
>>
>> return 0;
>> +
>> +recycle_alloc_pg:
>> + prueth_reset_rx_chan(&emac->rx_chns, PRUETH_MAX_RX_FLOWS, false);
>> +
>> + return ret;
>> }
>> EXPORT_SYMBOL_GPL(prueth_prepare_rx_chan);
>>
>> @@ -958,6 +1009,9 @@ void prueth_reset_rx_chan(struct prueth_rx_chn *chn,
>> prueth_rx_cleanup, !!i);
>> if (disable)
>> k3_udma_glue_disable_rx_chn(chn->rx_chn);
>> +
>> + page_pool_destroy(chn->pg_pool);
>> + chn->pg_pool = NULL;
>> }
>> EXPORT_SYMBOL_GPL(prueth_reset_rx_chan);
>>
>> diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.h b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
>> index 329b46e9ee53..c7b906de18af 100644
>> --- a/drivers/net/ethernet/ti/icssg/icssg_prueth.h
>> +++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
>> @@ -33,6 +33,8 @@
>> #include <linux/dma/k3-udma-glue.h>
>>
>> #include <net/devlink.h>
>> +#include <net/xdp.h>
>> +#include <net/page_pool/helpers.h>
>>
>> #include "icssg_config.h"
>> #include "icss_iep.h"
>> @@ -131,6 +133,7 @@ struct prueth_rx_chn {
>> u32 descs_num;
>> unsigned int irq[ICSSG_MAX_RFLOWS]; /* separate irq per flow */
>> char name[32];
>> + struct page_pool *pg_pool;
>> };
>>
>> /* There are 4 Tx DMA channels, but the highest priority is CH3 (thread 3)
>> @@ -210,6 +213,10 @@ struct prueth_emac {
>> struct netdev_hw_addr_list vlan_mcast_list[MAX_VLAN_ID];
>> };
>>
>> +/* The buf includes headroom compatible with both skb and xdpf */
>> +#define PRUETH_HEADROOM_NA (max(XDP_PACKET_HEADROOM, NET_SKB_PAD) + NET_IP_ALIGN)
>> +#define PRUETH_HEADROOM ALIGN(PRUETH_HEADROOM_NA, sizeof(long))
>> +
>> /**
>> * struct prueth_pdata - PRUeth platform data
>> * @fdqring_mode: Free desc queue mode
>> @@ -410,9 +417,10 @@ int prueth_init_rx_chns(struct prueth_emac *emac,
>> struct prueth_rx_chn *rx_chn,
>> char *name, u32 max_rflows,
>> u32 max_desc_num);
>> -int prueth_dma_rx_push(struct prueth_emac *emac,
>> - struct sk_buff *skb,
>> - struct prueth_rx_chn *rx_chn);
>> +int prueth_dma_rx_push_mapped(struct prueth_emac *emac,
>> + struct prueth_rx_chn *rx_chn,
>> + struct page *page, u32 buf_len);
>> +unsigned int prueth_rxbuf_total_len(unsigned int len);
>> void emac_rx_timestamp(struct prueth_emac *emac,
>> struct sk_buff *skb, u32 *psdata);
>> enum netdev_tx icssg_ndo_start_xmit(struct sk_buff *skb, struct net_device *ndev);
>> diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth_sr1.c b/drivers/net/ethernet/ti/icssg/icssg_prueth_sr1.c
>> index 64a19ff39562..aeeb8a50376b 100644
>> --- a/drivers/net/ethernet/ti/icssg/icssg_prueth_sr1.c
>> +++ b/drivers/net/ethernet/ti/icssg/icssg_prueth_sr1.c
>> @@ -274,10 +274,12 @@ static struct sk_buff *prueth_process_rx_mgm(struct prueth_emac *emac,
>
> This is how we can get rid of skb from RX management code.
>
> Change return type of this function and callers to struct page *
>
>> struct prueth_rx_chn *rx_chn = &emac->rx_mgm_chn;
>> struct net_device *ndev = emac->ndev;
>> struct cppi5_host_desc_t *desc_rx;
>> - struct sk_buff *skb, *new_skb;
>> + struct page *page, *new_page;
>> dma_addr_t desc_dma, buf_dma;
>> u32 buf_dma_len, pkt_len;
>> + struct sk_buff *skb;
>
> drop skb
>
>> void **swdata;
>> + void *pa;
>
> drop pa
>
>> int ret;
>>
>> ret = k3_udma_glue_pop_rx_chn(rx_chn->rx_chn, flow_id, &desc_dma);
>> @@ -299,32 +301,35 @@ static struct sk_buff *prueth_process_rx_mgm(struct prueth_emac *emac,
>> }
>>
>> swdata = cppi5_hdesc_get_swdata(desc_rx);
>> - skb = *swdata;
>> + page = *swdata;
>> cppi5_hdesc_get_obuf(desc_rx, &buf_dma, &buf_dma_len);
>> pkt_len = cppi5_hdesc_get_pktlen(desc_rx);
>>
>> dma_unmap_single(rx_chn->dma_dev, buf_dma, buf_dma_len, DMA_FROM_DEVICE);
>> k3_cppi_desc_pool_free(rx_chn->desc_pool, desc_rx);
>>
>> - new_skb = netdev_alloc_skb_ip_align(ndev, PRUETH_MAX_PKT_SIZE);
>> + new_page = page_pool_dev_alloc_pages(rx_chn->pg_pool);
>> /* if allocation fails we drop the packet but push the
>> * descriptor back to the ring with old skb to prevent a stall
>> */
>> - if (!new_skb) {
>> + if (!new_page) {
>> netdev_err(ndev,
>> - "skb alloc failed, dropped mgm pkt from flow %d\n",
>> + "page alloc failed, dropped mgm pkt from flow %d\n",
>> flow_id);
>> - new_skb = skb;
>> + new_page = page;
>> skb = NULL; /* return NULL */
>
> page = NULL;
>
>> } else {
>> /* return the filled skb */
>> + pa = page_address(page);
>> + skb = napi_build_skb(pa, PAGE_SIZE);
>> skb_put(skb, pkt_len);
>> }
>
> drop entire else
>
>>
>> /* queue another DMA */
>> - ret = prueth_dma_rx_push(emac, new_skb, &emac->rx_mgm_chn);
>> + ret = prueth_dma_rx_push_mapped(emac, &emac->rx_chns, new_page,
>> + PRUETH_MAX_PKT_SIZE);
>> if (WARN_ON(ret < 0))
>> - dev_kfree_skb_any(new_skb);
>> + page_pool_recycle_direct(rx_chn->pg_pool, new_page);
>>
>> return skb;
>
> return page;
>
>> }
>
>
> In the callers to prueth_process_rx_mgm() use page_address(page) to get the virtual
> address i.e. in place of skb->data.
> Where you are freeing the SKB do a page_pool_recycle_direct(page->pg_pool, page);
>
Ok thanks, I will incorporate these changes in v4 and send these patches
to Diogo for testing.
Regards,
Meghana
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