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 667EDCDB465 for ; Mon, 16 Oct 2023 09:53:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231372AbjJPJx3 (ORCPT ); Mon, 16 Oct 2023 05:53:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37906 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230219AbjJPJx1 (ORCPT ); Mon, 16 Oct 2023 05:53:27 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B4D69AD; Mon, 16 Oct 2023 02:53:25 -0700 (PDT) Date: Mon, 16 Oct 2023 11:53:21 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1697450003; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8ZwQf1eErlCBg5WbOcq8pGfvcWHlytZnteUJdOl47Zg=; b=iekvbj8nVBgBKHp54JDJ2zdV2IRrA92G5gtS46afyKZUREHU8rn/OLoYpqleDGokq+RxCH 6K3uRMFn2cxMzHOMARpqpWW4ZT0ggN9PbFzHZDz1BImwRdKTUTXlwqpQeAd5v0Ls/cBBTb cOIX8e0ScosNFsXHkpdhjVZ2pxPVw9mgFA2xP+K7EMf2ryRUezN3EW+1edGwZ8wh0th4QP cBi47q7LL3o/MeuIs9SzzEtfIsEQBDV9OqhKPMWsx1YqmvpXi3CmlGIpM1pLljm6lkG4uN bzc7lZ9kVVnlqy+WjHEbFdSyk5WbOH015rhgyH4Hr7ld8gKklpf5VtHEP3bMYw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1697450003; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8ZwQf1eErlCBg5WbOcq8pGfvcWHlytZnteUJdOl47Zg=; b=31v1lpj1/2JCjhus7e1WwxJik7R7Wh0QYy/24EY//Rdz6CtSoqh+TG7t2rP0cQjaZ2PEVT rLodbOX8XIga3yBQ== From: Sebastian Andrzej Siewior To: Jakub Kicinski Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, "David S. Miller" , Eric Dumazet , Paolo Abeni , Peter Zijlstra , Thomas Gleixner , Wander Lairson Costa Subject: Re: [PATCH net-next 0/2] net: Use SMP threads for backlog NAPI (or optional). Message-ID: <20231016095321.4xzKQ5Cd@linutronix.de> References: <20230929162121.1822900-1-bigeasy@linutronix.de> <20231004154609.6007f1a0@kernel.org> <20231007155957.aPo0ImuG@linutronix.de> <20231009180937.2afdc4c1@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <20231009180937.2afdc4c1@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sorry, getting back that late, I was traveling the last two weeks=E2=80=A6 On 2023-10-09 18:09:37 [-0700], Jakub Kicinski wrote: > On Sat, 7 Oct 2023 17:59:57 +0200 Sebastian Andrzej Siewior wrote: > > Apologies if I misunderstood. You said to make it optional which I did > > with the static key in the second patch of this series. The first patch > > is indeed not what we talked about I just to show what it would look > > like now that there is no "delay" for backlog-NAPI on the local CPU. > >=20 > > If the optional part is okay then I can repost only that patch against > > current net-next. >=20 > Do we have reason to believe nobody uses RPS? Not sure what you relate to. I would assume that RPS is used in general on actual devices and not on loopback where backlog is used. But it is just an assumption. The performance drop, which I observed with RPS and stress-ng --udp, is within the same range with threads and IPIs (based on memory). I can re-run the test and provide actual numbers if you want. Sebastian