From nobody Tue Feb 10 00:58:52 2026 Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5561A211265; Fri, 10 Jan 2025 13:14:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.190 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736514866; cv=none; b=a/7JpfxxVTA7gRVrIkJwcHl2M55is2YlRZrumtNhOVESH6vIb9q2ZRVsmpA23VebPU6/VzHlfCMRTu3n6qoFPbVB+BAk0yrns9wYk5bsw5nVPzZc/OBY4hqMQ6eUszMgkpfof/vnYiE5Krg28WAqef0cQqHWh5FTEwSzLKdTuto= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736514866; c=relaxed/simple; bh=EL2MA+bIrsR2m3M/6akl14KgoJ03XzKrxhrcoehg/ko=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=UbyqB4tSbu4v4pZatySfnR5xt0smYmaPGh3VSrvSmdeLKZd1cb9Dj9CVpvlXLs17z/7K6UEqQp0sz8BuvW5X9dtPXvAoC7eS6RQAryj34yLDpB6UYr8l7jJ19S3GT0/P6Oz40b5H06tDAD+lSSIigswjUOXfPwkdRTPlTziCnNc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.190 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.163]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4YV29x08fhz22kFn; Fri, 10 Jan 2025 21:12:05 +0800 (CST) Received: from dggpemf200006.china.huawei.com (unknown [7.185.36.61]) by mail.maildlp.com (Postfix) with ESMTPS id 5E096180044; Fri, 10 Jan 2025 21:14:22 +0800 (CST) Received: from localhost.localdomain (10.90.30.45) by dggpemf200006.china.huawei.com (7.185.36.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 10 Jan 2025 21:14:22 +0800 From: Yunsheng Lin To: , , CC: , , , Yunsheng Lin , Robin Murphy , Alexander Duyck , IOMMU , Jesper Dangaard Brouer , Ilias Apalodimas , Eric Dumazet , Simon Horman , , Subject: [PATCH net-next v7 8/8] page_pool: use list instead of array for alloc cache Date: Fri, 10 Jan 2025 21:07:02 +0800 Message-ID: <20250110130703.3814407-9-linyunsheng@huawei.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20250110130703.3814407-1-linyunsheng@huawei.com> References: <20250110130703.3814407-1-linyunsheng@huawei.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemf200006.china.huawei.com (7.185.36.61) Content-Type: text/plain; charset="utf-8" As the alloc cache is always protected by NAPI context protection, use encoded_next as a pointer to a next item to avoid the using the array. Testing shows there is about 3ns improvement for the performance of 'time_bench_page_pool01_fast_path' test case. CC: Robin Murphy CC: Alexander Duyck CC: IOMMU Signed-off-by: Yunsheng Lin --- include/net/page_pool/types.h | 1 + net/core/page_pool.c | 59 ++++++++++++++++++++++++++++------- 2 files changed, 48 insertions(+), 12 deletions(-) diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h index d01c5d26cd56..ff6ebacaa57a 100644 --- a/include/net/page_pool/types.h +++ b/include/net/page_pool/types.h @@ -50,6 +50,7 @@ #define PP_ALLOC_CACHE_REFILL 64 struct pp_alloc_cache { u32 count; + struct page_pool_item *list; netmem_ref cache[PP_ALLOC_CACHE_SIZE]; =20 /* Keep batched refilled pages here to avoid doing the atomic operation diff --git a/net/core/page_pool.c b/net/core/page_pool.c index eb18ab0999e6..459f783a354a 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -386,6 +386,27 @@ static netmem_ref page_pool_consume_ring(struct page_p= ool *pool) return list->pp_netmem; } =20 +static netmem_ref __page_pool_consume_alloc(struct page_pool *pool) +{ + struct page_pool_item *item =3D pool->alloc.list; + + pool->alloc.list =3D page_pool_item_get_next(item); + pool->alloc.count--; + + return item->pp_netmem; +} + +static void __page_pool_recycle_in_alloc(struct page_pool *pool, + netmem_ref netmem) +{ + struct page_pool_item *item; + + item =3D netmem_get_pp_item(netmem); + page_pool_item_set_next(item, pool->alloc.list); + pool->alloc.list =3D item; + pool->alloc.count++; +} + static __always_inline void __page_pool_release_page_dma(struct page_pool = *pool, netmem_ref netmem, bool destroyed) @@ -681,10 +702,12 @@ static void __page_pool_return_page(struct page_pool = *pool, netmem_ref netmem, =20 static noinline netmem_ref page_pool_refill_alloc_cache(struct page_pool *= pool) { - struct page_pool_item *refill; + struct page_pool_item *refill, *alloc, *curr; netmem_ref netmem; int pref_nid; /* preferred NUMA node */ =20 + DEBUG_NET_WARN_ON_ONCE(pool->alloc.count || pool->alloc.list); + /* Quicker fallback, avoid locks when ring is empty */ refill =3D pool->alloc.refill; if (unlikely(!refill && !READ_ONCE(pool->ring.list))) { @@ -702,6 +725,7 @@ static noinline netmem_ref page_pool_refill_alloc_cache= (struct page_pool *pool) pref_nid =3D numa_mem_id(); /* will be zero like page_to_nid() */ #endif =20 + alloc =3D NULL; /* Refill alloc array, but only if NUMA match */ do { if (unlikely(!refill)) { @@ -710,10 +734,13 @@ static noinline netmem_ref page_pool_refill_alloc_cac= he(struct page_pool *pool) break; } =20 + curr =3D refill; netmem =3D refill->pp_netmem; refill =3D page_pool_item_get_next(refill); if (likely(netmem_is_pref_nid(netmem, pref_nid))) { - pool->alloc.cache[pool->alloc.count++] =3D netmem; + page_pool_item_set_next(curr, alloc); + pool->alloc.count++; + alloc =3D curr; } else { /* NUMA mismatch; * (1) release 1 page to page-allocator and @@ -733,7 +760,9 @@ static noinline netmem_ref page_pool_refill_alloc_cache= (struct page_pool *pool) /* Return last page */ if (likely(pool->alloc.count > 0)) { atomic_sub(pool->alloc.count, &pool->ring.count); - netmem =3D pool->alloc.cache[--pool->alloc.count]; + netmem =3D alloc->pp_netmem; + pool->alloc.list =3D page_pool_item_get_next(alloc); + pool->alloc.count--; alloc_stat_inc(pool, refill); } =20 @@ -748,7 +777,7 @@ static netmem_ref __page_pool_get_cached(struct page_po= ol *pool) /* Caller MUST guarantee safe non-concurrent access, e.g. softirq */ if (likely(pool->alloc.count)) { /* Fast-path */ - netmem =3D pool->alloc.cache[--pool->alloc.count]; + netmem =3D __page_pool_consume_alloc(pool); alloc_stat_inc(pool, fast); } else { netmem =3D page_pool_refill_alloc_cache(pool); @@ -867,6 +896,7 @@ static struct page *__page_pool_alloc_page_order(struct= page_pool *pool, static noinline netmem_ref __page_pool_alloc_pages_slow(struct page_pool *= pool, gfp_t gfp) { + struct page_pool_item *curr, *alloc =3D NULL; const int bulk =3D PP_ALLOC_CACHE_REFILL; unsigned int pp_order =3D pool->p.order; bool dma_map =3D pool->dma_map; @@ -877,9 +907,8 @@ static noinline netmem_ref __page_pool_alloc_pages_slow= (struct page_pool *pool, if (unlikely(pp_order)) return page_to_netmem(__page_pool_alloc_page_order(pool, gfp)); =20 - /* Unnecessary as alloc cache is empty, but guarantees zero count */ - if (unlikely(pool->alloc.count > 0)) - return pool->alloc.cache[--pool->alloc.count]; + /* alloc cache should be empty */ + DEBUG_NET_WARN_ON_ONCE(pool->alloc.count || pool->alloc.list); =20 /* Mark empty alloc.cache slots "empty" for alloc_pages_bulk_array */ memset(&pool->alloc.cache, 0, sizeof(void *) * bulk); @@ -907,7 +936,11 @@ static noinline netmem_ref __page_pool_alloc_pages_slo= w(struct page_pool *pool, continue; } =20 - pool->alloc.cache[pool->alloc.count++] =3D netmem; + curr =3D netmem_get_pp_item(netmem); + page_pool_item_set_next(curr, alloc); + pool->alloc.count++; + alloc =3D curr; + /* Track how many pages are held 'in-flight' */ pool->pages_state_hold_cnt++; trace_page_pool_state_hold(pool, netmem, @@ -916,7 +949,9 @@ static noinline netmem_ref __page_pool_alloc_pages_slow= (struct page_pool *pool, =20 /* Return last page */ if (likely(pool->alloc.count > 0)) { - netmem =3D pool->alloc.cache[--pool->alloc.count]; + netmem =3D alloc->pp_netmem; + pool->alloc.list =3D page_pool_item_get_next(alloc); + pool->alloc.count--; alloc_stat_inc(pool, slow); } else { netmem =3D 0; @@ -1086,7 +1121,7 @@ static bool page_pool_recycle_in_cache(netmem_ref net= mem, } =20 /* Caller MUST have verified/know (page_ref_count(page) =3D=3D 1) */ - pool->alloc.cache[pool->alloc.count++] =3D netmem; + __page_pool_recycle_in_alloc(pool, netmem); recycle_stat_inc(pool, cached); return true; } @@ -1431,7 +1466,7 @@ static void page_pool_empty_alloc_cache_once(struct p= age_pool *pool) * call concurrently. */ while (pool->alloc.count) { - netmem =3D pool->alloc.cache[--pool->alloc.count]; + netmem =3D __page_pool_consume_alloc(pool); page_pool_return_page(pool, netmem); } =20 @@ -1571,7 +1606,7 @@ void page_pool_update_nid(struct page_pool *pool, int= new_nid) =20 /* Flush pool alloc cache, as refill will check NUMA node */ while (pool->alloc.count) { - netmem =3D pool->alloc.cache[--pool->alloc.count]; + netmem =3D __page_pool_consume_alloc(pool); __page_pool_return_page(pool, netmem, false); } } --=20 2.33.0