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 002B9C433F5 for ; Mon, 6 Dec 2021 03:07:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235555AbhLFDKd (ORCPT ); Sun, 5 Dec 2021 22:10:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60350 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235402AbhLFDKc (ORCPT ); Sun, 5 Dec 2021 22:10:32 -0500 Received: from mail-il1-x134.google.com (mail-il1-x134.google.com [IPv6:2607:f8b0:4864:20::134]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A9664C0613F8; Sun, 5 Dec 2021 19:07:04 -0800 (PST) Received: by mail-il1-x134.google.com with SMTP id m5so8801002ilh.11; Sun, 05 Dec 2021 19:07:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:content-transfer-encoding; bh=X55f6rIyxMAeTkg3TDveTFlB+gqqpA+K+Mun7+M717g=; b=mknr1zSxDyDbvYIPNQQVYXP3WrHtVHy2+70P/ZIsDsoqtkDAtzuEYjDoIJkV1J73DA bujhgI48w3dTh8yi+irxuVzCiJagWpFVlF5OTvv/VtpAw3q5ZDb7sD1bHZ32lJcqTMco YzCbWSgJqs9x8KZoEk7jji2Z2XAZXoJj/Q1ph+x8111Oks0zvssR0NKQksxNGz8sDshX i+FXsPAJUh6Yrc3md4//SS5wgd5h681kHo7d7leh9Pb4b4KZFvZQ4xt4f7Moku6lpv91 Sfzk/Vzt9wgyRm2SStVmIwUH4/XESnYm3ibbXN7kKTzkTP34xtIhBsZLHVEE7VkhYg3H SVTg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:content-transfer-encoding; bh=X55f6rIyxMAeTkg3TDveTFlB+gqqpA+K+Mun7+M717g=; b=CKlqCDp4E1Gp9L6az6yBnm2kduM+9G37ahjfgKo5jciVf2BiOjQDnqZNcmzrme/UOX JrvIQ+0Br+NUB84/crE4OkafPFDk0oDNfWlCym7kZ9wpWl0cvmohNdGtD5Nj9qDVKm7n C5v8GBZAvey2vdWKduMJ8a5DCYS9wXgBOD0T6LJp2NEwPOp5jMMQGHomV5vdx3Gp9Ul4 2DO9eSkwpfnIbuTwObCVC1kM6LkCDYPtihWbtSudRfw94hKFt1ZkOMCORLVlD1ZaTMwq Q5Y6XzZEfYM8eqSqUSwdqfV1Mee9xXCnCBozi1aeGI6OdmssxRz9ytwmxwMe8q21qute PAaw== X-Gm-Message-State: AOAM533tbvapWJUK/cgS2tnMDy9vyF7tmzK/OSpqi5KQjtCVuKfD+EK9 UE2EJMP0EIce71u4HtkjL/4= X-Google-Smtp-Source: ABdhPJxO5BUmaKTFICc1LNTGkVxjmfBxmj4LMsA1F93TMnKyH6vkrW94naPxPSDTye2MBNxetH91Zg== X-Received: by 2002:a92:c248:: with SMTP id k8mr27590450ilo.297.1638760024085; Sun, 05 Dec 2021 19:07:04 -0800 (PST) Received: from localhost ([172.243.151.11]) by smtp.gmail.com with ESMTPSA id l3sm7138439ilv.37.2021.12.05.19.07.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 05 Dec 2021 19:07:03 -0800 (PST) Date: Sun, 05 Dec 2021 19:06:52 -0800 From: John Fastabend To: Lorenzo Bianconi , bpf@vger.kernel.org, netdev@vger.kernel.org Cc: lorenzo.bianconi@redhat.com, davem@davemloft.net, kuba@kernel.org, ast@kernel.org, daniel@iogearbox.net, shayagr@amazon.com, john.fastabend@gmail.com, dsahern@kernel.org, brouer@redhat.com, echaudro@redhat.com, jasowang@redhat.com, alexander.duyck@gmail.com, saeed@kernel.org, maciej.fijalkowski@intel.com, magnus.karlsson@intel.com, tirthendu.sarkar@intel.com, toke@redhat.com Message-ID: <61ad7e4cbc69d_444e20888@john.notmuch> In-Reply-To: <95151f4b8a25ce38243e82f0a82104d0f46fb33a.1638272238.git.lorenzo@kernel.org> References: <95151f4b8a25ce38243e82f0a82104d0f46fb33a.1638272238.git.lorenzo@kernel.org> Subject: RE: [PATCH v19 bpf-next 03/23] net: mvneta: update mb bit before passing the xdp buffer to eBPF layer Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Lorenzo Bianconi wrote: > Update multi-buffer bit (mb) in xdp_buff to notify XDP/eBPF layer and > XDP remote drivers if this is a "non-linear" XDP buffer. Access > skb_shared_info only if xdp_buff mb is set in order to avoid possible > cache-misses. > > Signed-off-by: Lorenzo Bianconi [...] > @@ -2320,8 +2325,12 @@ mvneta_swbm_build_skb(struct mvneta_port *pp, struct page_pool *pool, > struct xdp_buff *xdp, u32 desc_status) > { > struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp); > - int i, num_frags = sinfo->nr_frags; > struct sk_buff *skb; > + u8 num_frags; > + int i; > + > + if (unlikely(xdp_buff_is_mb(xdp))) > + num_frags = sinfo->nr_frags; Doesn't really need a respin IMO, but rather an observation. Its not obvious to me the unlikely/likely pair here is wanted. Seems it could be relatively common for some applications sending jumbo frames. Maybe worth some experimenting in the future. > > skb = build_skb(xdp->data_hard_start, PAGE_SIZE); > if (!skb) > @@ -2333,6 +2342,9 @@ mvneta_swbm_build_skb(struct mvneta_port *pp, struct page_pool *pool, > skb_put(skb, xdp->data_end - xdp->data); > skb->ip_summed = mvneta_rx_csum(pp, desc_status); > > + if (likely(!xdp_buff_is_mb(xdp))) > + goto out; > + > for (i = 0; i < num_frags; i++) { > skb_frag_t *frag = &sinfo->frags[i];