From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00CF6C6FA8B for ; Thu, 22 Sep 2022 09:58:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231154AbiIVJ6F (ORCPT ); Thu, 22 Sep 2022 05:58:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231246AbiIVJ5h (ORCPT ); Thu, 22 Sep 2022 05:57:37 -0400 Received: from mail-wm1-x331.google.com (mail-wm1-x331.google.com [IPv6:2a00:1450:4864:20::331]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A748D58AC for ; Thu, 22 Sep 2022 02:57:01 -0700 (PDT) Received: by mail-wm1-x331.google.com with SMTP id z13-20020a7bc7cd000000b003b5054c6f9bso461225wmk.2 for ; Thu, 22 Sep 2022 02:57:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date; bh=TX+dZFKc01rzMEgsWJ5WshpFDtmg9ORNYvjpFUtfE7U=; b=wrbiuc31HYkBNQTsgI2G+/Oy6SygApb1Gh45M7m6bKMrSjJ2jz03iPH4gGLoc/KH4R JeLNtg6Glds/tAa/5pHssmv9X/lwD/04j12/cLOYi6SpG3+qU8HG1XKJcZoZokg9lWSl jyaVgjkTw2MGlx97EuyxqeolFlRCkSA3xhhbzT1auFqu9TbuHDVsTE7bjOdgz1kjCATt 5VXu0CIMpN2Qy5w/1u27Axoo/vwnosicUW5x69YtPRVEv4g+3P/ePsxy6Ib8byTGg7RV ItjUHqFN5lbmChFkLX8UqlRPoIiFboAzcIYGJNcB2xyiuKzWfbWAVCxOCwkasH45/oQ5 kQSQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=TX+dZFKc01rzMEgsWJ5WshpFDtmg9ORNYvjpFUtfE7U=; b=ky5Z58bcTuvz2DJe7U08tFQUZJhWcC0gmnvGbTOTlPh7Uiyu98ZTHahTLx+5rmM5bx o78ZDGj1ZL8Prwv1LlngRZwEp7VeMZu2axed393gMryQbN8tz8gldt97Gdub+OjGwB7w 4ZPMx/JA8p3d77rEnXgOzx5OOiMshVoIAe9kaj4lScPg7udiSv5T/79MzA/IHgYo05xm xOSM7EysEO9R34n6BX5H5S+6ocDm9/8vQpMh2UYOwXts3KxJqhpf9PV9v9QBdmQeUQHT ZZilVj0LCwe3PhPnDlRO3UIaqKmqgaI59JdBvYuvjrngBxw2LnjvqWH6WUttt5hTjHnr TWoQ== X-Gm-Message-State: ACrzQf3GRVrhQ2B7bBeaN/btrmUWN4hG1veCB0db9eH9cQ9Cy+crSO+o qA+aWxJj8np8PWmo7jZH1Scanw== X-Google-Smtp-Source: AMsMyM6i6UfcSL8Kwei3PzQZYMd+09H2UCH5uPAZ58h/kYqOTqoT/Xto/7pTCxlRgy/goVe7ATBGYA== X-Received: by 2002:a1c:4b03:0:b0:3b4:74d3:b4c5 with SMTP id y3-20020a1c4b03000000b003b474d3b4c5mr1721728wma.96.1663840619776; Thu, 22 Sep 2022 02:56:59 -0700 (PDT) Received: from hades ([46.103.15.185]) by smtp.gmail.com with ESMTPSA id l30-20020a05600c1d1e00b003a62400724bsm6408472wms.0.2022.09.22.02.56.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Sep 2022 02:56:58 -0700 (PDT) Date: Thu, 22 Sep 2022 12:56:56 +0300 From: Ilias Apalodimas To: Jesper Dangaard Brouer Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, Lorenzo Bianconi , mtahhan@redhat.com, mcroce@microsoft.com Subject: Re: [PATCH net-next] xdp: improve page_pool xdp_return performance Message-ID: References: <166377993287.1737053.10258297257583703949.stgit@firesoul> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <166377993287.1737053.10258297257583703949.stgit@firesoul> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi Jesper, On Wed, Sep 21, 2022 at 07:05:32PM +0200, Jesper Dangaard Brouer wrote: > During LPC2022 I meetup with my page_pool co-maintainer Ilias. When > discussing page_pool code we realised/remembered certain optimizations > had not been fully utilised. > > Since commit c07aea3ef4d4 ("mm: add a signature in struct page") struct > page have a direct pointer to the page_pool object this page was > allocated from. > > Thus, with this info it is possible to skip the rhashtable_lookup to > find the page_pool object in __xdp_return(). > > The rcu_read_lock can be removed as it was tied to xdp_mem_allocator. > The page_pool object is still safe to access as it tracks inflight pages > and (potentially) schedules final release from a work queue. > > Created a micro benchmark of XDP redirecting from mlx5 into veth with > XDP_DROP bpf-prog on the peer veth device. This increased performance > 6.5% from approx 8.45Mpps to 9Mpps corresponding to using 7 nanosec > (27 cycles at 3.8GHz) less per packet. Thanks for the detailed testing > > Suggested-by: Ilias Apalodimas > Signed-off-by: Jesper Dangaard Brouer > --- > net/core/xdp.c | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > diff --git a/net/core/xdp.c b/net/core/xdp.c > index 24420209bf0e..844c9d99dc0e 100644 > --- a/net/core/xdp.c > +++ b/net/core/xdp.c > @@ -375,19 +375,17 @@ EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model); > void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct, > struct xdp_buff *xdp) > { > - struct xdp_mem_allocator *xa; > struct page *page; > > switch (mem->type) { > case MEM_TYPE_PAGE_POOL: > - rcu_read_lock(); > - /* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */ > - xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params); > page = virt_to_head_page(data); > if (napi_direct && xdp_return_frame_no_direct()) > napi_direct = false; > - page_pool_put_full_page(xa->page_pool, page, napi_direct); > - rcu_read_unlock(); > + /* No need to check ((page->pp_magic & ~0x3UL) == PP_SIGNATURE) > + * as mem->type knows this a page_pool page > + */ > + page_pool_put_full_page(page->pp, page, napi_direct); > break; > case MEM_TYPE_PAGE_SHARED: > page_frag_free(data); > > Reviewed-by: Ilias Apalodimas