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 7E54CC61DA4 for ; Thu, 16 Mar 2023 01:36:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229704AbjCPBg4 (ORCPT ); Wed, 15 Mar 2023 21:36:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53496 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229487AbjCPBgz (ORCPT ); Wed, 15 Mar 2023 21:36:55 -0400 Received: from mail-pl1-x62a.google.com (mail-pl1-x62a.google.com [IPv6:2607:f8b0:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31B9FCC1C for ; Wed, 15 Mar 2023 18:36:52 -0700 (PDT) Received: by mail-pl1-x62a.google.com with SMTP id i5so180715pla.2 for ; Wed, 15 Mar 2023 18:36:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20210112.gappssmtp.com; s=20210112; t=1678930611; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=l+1mkwqCPR3Q82+dWcQmlIn4W8/s1X0EYzQFgWa9j8U=; b=syDM9CXv6fPa2NmyGh7pfOaXdvcpRw7E1YjFA3yvZoU+4VSaM2tTCnFXDnxMAab+UA zCxpRpyModXdqd1FkYh3OsJAqLy5ZpjDeBLh9KlCRWTwy2qmHs7c9/uHnIm26X0LK/dT NWlan0/kRN6b10t1yg1sFTtl4StVxy1qfvBDL/bpouOskvGzB9BC8wV+Tf3Y6h9Ug7MA wKW+3KW0bDcOIo2NhmdmryVvlXgHESzqvCgGJ1tSChKL6gYodGsgotVcQG1QuKWRKtCJ E3c/sAscH9TaRIKmwL5OaUxPKtwgariZdishLloAL8sZ6YgvLHGbN0zGoO/IqBOr3Kgk W3gg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678930611; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=l+1mkwqCPR3Q82+dWcQmlIn4W8/s1X0EYzQFgWa9j8U=; b=J+DG3RhobUhRq+T6lpqCIFgGW2Quip6jcWg1dvL/M+CrITRUgTHth1UhVd5M1WAhj0 3qMf4DZgcufJSJCYzDgAAhkO7NyouVdDGydZdBW2ahfbnSqCB+sw6Ds29kLcWnTTTubR DP49YwuAwzg6ZGwlSMLePBUBs1uI+UaVyhpPpiX4/4QPoJQoZ3XC0UmPpgjoBDe2L+Xk Mk28R1h2t6Zv2c26BZIDU7P3dnNU4nk7cMixdwOkYcm05fM1f5EtH7OvseYWS+loXcsy X0uJkIQqjaNO7QozC2qQtoDxmMVtEKvsw1nkj3Y3vscpu8Xil6LDdCLepxC8+/UUnSa4 aNbg== X-Gm-Message-State: AO0yUKXlsyCLkvHHXLNz1OrBrxyb/LCOUQfsPPMGbGOCFXlhFukMs+Wh fKNzCrsWa5K66oyn7gUzXBhekA== X-Google-Smtp-Source: AK7set8RYhRM2w+zIADodMW6Htt8G7DemfZJT5RsmEpKoTTWEjNiQYml0jDfFNcPGt05QNINUra6sg== X-Received: by 2002:a05:6a20:bfd6:b0:cb:c2a8:2c48 with SMTP id gs22-20020a056a20bfd600b000cbc2a82c48mr1945165pzb.17.1678930611649; Wed, 15 Mar 2023 18:36:51 -0700 (PDT) Received: from hermes.local (204-195-120-218.wavecable.com. [204.195.120.218]) by smtp.gmail.com with ESMTPSA id y16-20020a631810000000b004b1fef0bf16sm3967321pgl.73.2023.03.15.18.36.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Mar 2023 18:36:51 -0700 (PDT) Date: Wed, 15 Mar 2023 18:36:49 -0700 From: Stephen Hemminger To: Jakub Kicinski Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, jesse.brandeburg@intel.com, anthony.l.nguyen@intel.com, corbet@lwn.net, linux-doc@vger.kernel.org Subject: Re: [PATCH net-next] docs: networking: document NAPI Message-ID: <20230315183649.7f42b1f0@hermes.local> In-Reply-To: <20230315161142.48de9d98@kernel.org> References: <20230315223044.471002-1-kuba@kernel.org> <20230315155202.2bba7e20@hermes.local> <20230315161142.48de9d98@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, 15 Mar 2023 16:11:42 -0700 Jakub Kicinski wrote: > > > > The one thing missing, is how to handle level vs edge triggered interrupts. > > For level triggered interrupts, the re-enable is inherently not racy. > > I.e re-enabling interrupt when packet is present will cause an interrupt. > > But for devices with edge triggered interrupts, it is often necessary to > > poll and manually schedule again. Older documentation referred to this > > as the "rotten packet" problem. > > > > Maybe this is no longer a problem for drivers? > > Or maybe all new hardware uses PCI MSI and is level triggered? > > It's still a problem depending on the exact design of the interrupt > controller in the chip / tradeoffs the SW wants to make. > I haven't actually read the LF doc, because I wasn't sure about the > licenses (sigh) I wrote the old NAPI from some older info that was available back then.