From patchwork Wed Jan 13 13:37:13 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Lobakin X-Patchwork-Id: 362635 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1E69DC433E6 for ; Wed, 13 Jan 2021 13:38:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C98EA23432 for ; Wed, 13 Jan 2021 13:38:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726733AbhAMNh7 (ORCPT ); Wed, 13 Jan 2021 08:37:59 -0500 Received: from mail1.protonmail.ch ([185.70.40.18]:53707 "EHLO mail1.protonmail.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725770AbhAMNh7 (ORCPT ); Wed, 13 Jan 2021 08:37:59 -0500 Date: Wed, 13 Jan 2021 13:37:13 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pm.me; s=protonmail; t=1610545035; bh=UfgI6Rrb/SGM19pvZtc2Put5d76631YVvNFcRByKDyk=; h=Date:To:From:Cc:Reply-To:Subject:In-Reply-To:References:From; b=FiJR8qIkTMbWnEjOFEEyCr3hSq5mmGIMsWdSKxVPbhuY6DMnAzbJ0WLY2iGqAmyw9 VpaKgK0nqCdeHjAChrRwnwyT5v6d3k7R3BSqW7C/e4cnFG014lmD/ojlXkZ81LrtuA U+TNew4ZPlrG5nfmjGxkkQkX7zWdIAnBpGpm5w2kDNXxhYCMdMqV2o2SE+nIie7dQ8 o7mZNjFT21k7MtSl2d3MK9MpgfWvrgIe2b0oiaFlyHfpq1U94WU0+vVW5g4arpCBrj QwlImqVhqBh1XO2i+qxgb7cIbOfOIwfFCThRXQ2C7v54AKqa0VfU5MehPSJERJDCka HSo4B0ExigOqQ== To: "David S. Miller" , Jakub Kicinski From: Alexander Lobakin Cc: Eric Dumazet , Edward Cree , Jonathan Lemon , Willem de Bruijn , Miaohe Lin , Alexander Lobakin , Steffen Klassert , Guillaume Nault , Yadu Kishore , Al Viro , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Reply-To: Alexander Lobakin Subject: [PATCH v2 net-next 2/3] skbuff: (re)use NAPI skb cache on allocation path Message-ID: <20210113133635.39402-2-alobakin@pm.me> In-Reply-To: <20210113133635.39402-1-alobakin@pm.me> References: <20210113133523.39205-1-alobakin@pm.me> <20210113133635.39402-1-alobakin@pm.me> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Instead of calling kmem_cache_alloc() every time when building a NAPI skb, (re)use skbuff_heads from napi_alloc_cache.skb_cache. Previously this cache was only used for bulk-freeing skbuff_heads consumed via napi_consume_skb() or __kfree_skb_defer(). Typical path is: - skb is queued for freeing from driver or stack, its skbuff_head goes into the cache instead of immediate freeing; - driver or stack requests NAPI skb allocation, an skbuff_head is taken from the cache instead of allocation. Corner cases: - if it's empty on skb allocation, bulk-allocate the first half; - if it's full on skb consuming, bulk-wipe the second half. Also try to balance its size after completing network softirqs (__kfree_skb_flush()). prefetchw() on CONFIG_SLUB is dropped since it makes no sense anymore. Suggested-by: Edward Cree Signed-off-by: Alexander Lobakin --- net/core/skbuff.c | 54 ++++++++++++++++++++++++++++++----------------- 1 file changed, 35 insertions(+), 19 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index dc3300dc2ac4..f42a3a04b918 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -364,6 +364,7 @@ struct sk_buff *build_skb_around(struct sk_buff *skb, EXPORT_SYMBOL(build_skb_around); #define NAPI_SKB_CACHE_SIZE 64 +#define NAPI_SKB_CACHE_HALF (NAPI_SKB_CACHE_SIZE / 2) struct napi_alloc_cache { struct page_frag_cache page; @@ -487,7 +488,15 @@ EXPORT_SYMBOL(__netdev_alloc_skb); static struct sk_buff *napi_skb_cache_get(struct napi_alloc_cache *nc) { - return kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC); + if (unlikely(!nc->skb_count)) + nc->skb_count = kmem_cache_alloc_bulk(skbuff_head_cache, + GFP_ATOMIC, + NAPI_SKB_CACHE_HALF, + nc->skb_cache); + if (unlikely(!nc->skb_count)) + return NULL; + + return nc->skb_cache[--nc->skb_count]; } /** @@ -867,40 +876,47 @@ void __consume_stateless_skb(struct sk_buff *skb) void __kfree_skb_flush(void) { struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache); + size_t count; + void **ptr; + + if (unlikely(nc->skb_count == NAPI_SKB_CACHE_HALF)) + return; + + if (nc->skb_count > NAPI_SKB_CACHE_HALF) { + count = nc->skb_count - NAPI_SKB_CACHE_HALF; + ptr = nc->skb_cache + NAPI_SKB_CACHE_HALF; - /* flush skb_cache if containing objects */ - if (nc->skb_count) { - kmem_cache_free_bulk(skbuff_head_cache, nc->skb_count, - nc->skb_cache); - nc->skb_count = 0; + kmem_cache_free_bulk(skbuff_head_cache, count, ptr); + nc->skb_count = NAPI_SKB_CACHE_HALF; + } else { + count = NAPI_SKB_CACHE_HALF - nc->skb_count; + ptr = nc->skb_cache + nc->skb_count; + + nc->skb_count += kmem_cache_alloc_bulk(skbuff_head_cache, + GFP_ATOMIC, count, + ptr); } } -static inline void _kfree_skb_defer(struct sk_buff *skb) +static void napi_skb_cache_put(struct sk_buff *skb) { struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache); /* drop skb->head and call any destructors for packet */ skb_release_all(skb); - /* record skb to CPU local list */ nc->skb_cache[nc->skb_count++] = skb; -#ifdef CONFIG_SLUB - /* SLUB writes into objects when freeing */ - prefetchw(skb); -#endif - - /* flush skb_cache if it is filled */ if (unlikely(nc->skb_count == NAPI_SKB_CACHE_SIZE)) { - kmem_cache_free_bulk(skbuff_head_cache, NAPI_SKB_CACHE_SIZE, - nc->skb_cache); - nc->skb_count = 0; + kmem_cache_free_bulk(skbuff_head_cache, NAPI_SKB_CACHE_HALF, + nc->skb_cache + NAPI_SKB_CACHE_HALF); + nc->skb_count = NAPI_SKB_CACHE_HALF; } } + void __kfree_skb_defer(struct sk_buff *skb) { - _kfree_skb_defer(skb); + napi_skb_cache_put(skb); } void napi_consume_skb(struct sk_buff *skb, int budget) @@ -925,7 +941,7 @@ void napi_consume_skb(struct sk_buff *skb, int budget) return; } - _kfree_skb_defer(skb); + napi_skb_cache_put(skb); } EXPORT_SYMBOL(napi_consume_skb);