Message-ID: <20241203173733.3181246-10-aleksander.lobakin@intel.com>
Date: Tue,  3 Dec 2024 18:37:32 +0100
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	John Fastabend <john.fastabend@...il.com>,
	Andrii Nakryiko <andrii@...nel.org>
Cc: Alexander Lobakin <aleksander.lobakin@...el.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Toke Høiland-Jørgensen <toke@...hat.com>,
	Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
	Stanislav Fomichev <sdf@...ichev.me>,
	Magnus Karlsson <magnus.karlsson@...el.com>,
	nex.sw.ncis.osdt.itp.upstreaming@...el.com,
	bpf@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH net-next v6 09/10] page_pool: allow mixing PPs within one bulk

The main reason for this change was to allow mixing pages from different
&page_pools within one &xdp_buff/&xdp_frame. Why not? With stuff like
devmem and io_uring zerocopy Rx, it's required to have separate PPs for
header buffers and payload buffers.
Adjust xdp_return_frame_bulk() and page_pool_put_netmem_bulk(), so that
they won't be tied to a particular pool. Let the latter create a
separate bulk of pages which's PP is different from the first netmem of
the bulk and process it after the main loop.
This greatly optimizes xdp_return_frame_bulk(): no more hashtable
lookups and forced flushes on PP mismatch. Also make
xdp_flush_frame_bulk() inline, as it's just one if + function call + one
u32 read, not worth extending the call ladder.

Co-developed-by: Toke Høiland-Jørgensen <toke@...hat.com> # iterative
Signed-off-by: Toke Høiland-Jørgensen <toke@...hat.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@...el.com>
---
 include/net/page_pool/types.h |  6 ++--
 include/net/xdp.h             | 16 ++++++---
 net/core/page_pool.c          | 61 ++++++++++++++++++++++++++---------
 net/core/xdp.c                | 29 +----------------
 4 files changed, 61 insertions(+), 51 deletions(-)

diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
index 1ea16b0e9c79..05a864031271 100644
--- a/include/net/page_pool/types.h
+++ b/include/net/page_pool/types.h
@@ -259,8 +259,7 @@ void page_pool_disable_direct_recycling(struct page_pool *pool);
 void page_pool_destroy(struct page_pool *pool);
 void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *),
 			   const struct xdp_mem_info *mem);
-void page_pool_put_netmem_bulk(struct page_pool *pool, netmem_ref *data,
-			       u32 count);
+void page_pool_put_netmem_bulk(netmem_ref *data, u32 count);
 #else
 static inline void page_pool_destroy(struct page_pool *pool)
 {
@@ -272,8 +271,7 @@ static inline void page_pool_use_xdp_mem(struct page_pool *pool,
 {
 }
 
-static inline void page_pool_put_netmem_bulk(struct page_pool *pool,
-					     netmem_ref *data, u32 count)
+static inline void page_pool_put_netmem_bulk(netmem_ref *data, u32 count)
 {
 }
 #endif
diff --git a/include/net/xdp.h b/include/net/xdp.h
index f4020b29122f..9e7eb8223513 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -11,6 +11,8 @@
 #include <linux/netdevice.h>
 #include <linux/skbuff.h> /* skb_shared_info */
 
+#include <net/page_pool/types.h>
+
 /**
  * DOC: XDP RX-queue information
  *
@@ -193,14 +195,12 @@ xdp_frame_is_frag_pfmemalloc(const struct xdp_frame *frame)
 #define XDP_BULK_QUEUE_SIZE	16
 struct xdp_frame_bulk {
 	int count;
-	void *xa;
 	netmem_ref q[XDP_BULK_QUEUE_SIZE];
 };
 
 static __always_inline void xdp_frame_bulk_init(struct xdp_frame_bulk *bq)
 {
-	/* bq->count will be zero'ed when bq->xa gets updated */
-	bq->xa = NULL;
+	bq->count = 0;
 }
 
 static inline struct skb_shared_info *
@@ -317,10 +317,18 @@ void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct,
 void xdp_return_frame(struct xdp_frame *xdpf);
 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
 void xdp_return_buff(struct xdp_buff *xdp);
-void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq);
 void xdp_return_frame_bulk(struct xdp_frame *xdpf,
 			   struct xdp_frame_bulk *bq);
 
+static inline void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
+{
+	if (unlikely(!bq->count))
+		return;
+
+	page_pool_put_netmem_bulk(bq->q, bq->count);
+	bq->count = 0;
+}
+
 static __always_inline unsigned int
 xdp_get_frame_len(const struct xdp_frame *xdpf)
 {
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 4c85b77cfdac..62cd1fcb9e97 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -841,7 +841,6 @@ EXPORT_SYMBOL(page_pool_put_unrefed_page);
 
 /**
  * page_pool_put_netmem_bulk() - release references on multiple netmems
- * @pool:	pool from which pages were allocated
  * @data:	array holding netmem references
  * @count:	number of entries in @data
  *
@@ -854,35 +853,58 @@ EXPORT_SYMBOL(page_pool_put_unrefed_page);
  * Please note the caller must not use data area after running
  * page_pool_put_netmem_bulk(), as this function overwrites it.
  */
-void page_pool_put_netmem_bulk(struct page_pool *pool, netmem_ref *data,
-			       u32 count)
+void page_pool_put_netmem_bulk(netmem_ref *data, u32 count)
 {
-	int i, bulk_len = 0;
-	bool allow_direct;
-	bool in_softirq;
+	bool allow_direct, in_softirq, again = false;
+	netmem_ref bulk[XDP_BULK_QUEUE_SIZE];
+	u32 i, bulk_len, foreign;
+	struct page_pool *pool;
 
-	allow_direct = page_pool_napi_local(pool);
+again:
+	pool = NULL;
+	bulk_len = 0;
+	foreign = 0;
 
 	for (i = 0; i < count; i++) {
-		netmem_ref netmem = netmem_compound_head(data[i]);
+		struct page_pool *netmem_pp;
+		netmem_ref netmem;
+
+		if (!again) {
+			netmem = netmem_compound_head(data[i]);
 
-		/* It is not the last user for the page frag case */
-		if (!page_pool_is_last_ref(netmem))
+			/* It is not the last user for the page frag case */
+			if (!page_pool_is_last_ref(netmem))
+				continue;
+		} else {
+			netmem = data[i];
+		}
+
+		netmem_pp = netmem_get_pp(netmem);
+		if (unlikely(!pool)) {
+			pool = netmem_pp;
+			allow_direct = page_pool_napi_local(pool);
+		} else if (netmem_pp != pool) {
+			/*
+			 * If the netmem belongs to a different page_pool, save
+			 * it for another round after the main loop.
+			 */
+			data[foreign++] = netmem;
 			continue;
+		}
 
 		netmem = __page_pool_put_page(pool, netmem, -1, allow_direct);
 		/* Approved for bulk recycling in ptr_ring cache */
 		if (netmem)
-			data[bulk_len++] = netmem;
+			bulk[bulk_len++] = netmem;
 	}
 
 	if (!bulk_len)
-		return;
+		goto out;
 
 	/* Bulk producer into ptr_ring page_pool cache */
 	in_softirq = page_pool_producer_lock(pool);
 	for (i = 0; i < bulk_len; i++) {
-		if (__ptr_ring_produce(&pool->ring, (__force void *)data[i])) {
+		if (__ptr_ring_produce(&pool->ring, (__force void *)bulk[i])) {
 			/* ring full */
 			recycle_stat_inc(pool, ring_full);
 			break;
@@ -893,13 +915,22 @@ void page_pool_put_netmem_bulk(struct page_pool *pool, netmem_ref *data,
 
 	/* Hopefully all pages was return into ptr_ring */
 	if (likely(i == bulk_len))
-		return;
+		goto out;
 
 	/* ptr_ring cache full, free remaining pages outside producer lock
 	 * since put_page() with refcnt == 1 can be an expensive operation
 	 */
 	for (; i < bulk_len; i++)
-		page_pool_return_page(pool, data[i]);
+		page_pool_return_page(pool, bulk[i]);
+
+out:
+	if (!foreign)
+		return;
+
+	count = foreign;
+	again = true;
+
+	goto again;
 }
 EXPORT_SYMBOL(page_pool_put_netmem_bulk);
 
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 938ad15c9857..56127e8ec85f 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -511,46 +511,19 @@ EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
  * xdp_frame_bulk is usually stored/allocated on the function
  * call-stack to avoid locking penalties.
  */
-void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
-{
-	struct xdp_mem_allocator *xa = bq->xa;
-
-	if (unlikely(!xa || !bq->count))
-		return;
-
-	page_pool_put_netmem_bulk(xa->page_pool, bq->q, bq->count);
-	/* bq->xa is not cleared to save lookup, if mem.id same in next bulk */
-	bq->count = 0;
-}
-EXPORT_SYMBOL_GPL(xdp_flush_frame_bulk);
 
 /* Must be called with rcu_read_lock held */
 void xdp_return_frame_bulk(struct xdp_frame *xdpf,
 			   struct xdp_frame_bulk *bq)
 {
-	struct xdp_mem_info *mem = &xdpf->mem;
-	struct xdp_mem_allocator *xa;
-
-	if (mem->type != MEM_TYPE_PAGE_POOL) {
+	if (xdpf->mem.type != MEM_TYPE_PAGE_POOL) {
 		xdp_return_frame(xdpf);
 		return;
 	}
 
-	xa = bq->xa;
-	if (unlikely(!xa)) {
-		xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
-		bq->count = 0;
-		bq->xa = xa;
-	}
-
 	if (bq->count == XDP_BULK_QUEUE_SIZE)
 		xdp_flush_frame_bulk(bq);
 
-	if (unlikely(mem->id != xa->mem.id)) {
-		xdp_flush_frame_bulk(bq);
-		bq->xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
-	}
-
 	if (unlikely(xdp_frame_has_frags(xdpf))) {
 		struct skb_shared_info *sinfo;
 		int i;
-- 
2.47.0

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