From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A1473606A31A for ; Thu, 22 Oct 2026 09:35:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=c1Bf0Aza; dkim=fail reason="signature verification failed" (2048-bit key, unprotected) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=desiato.20200630 header.b=N1Jev0D9; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b=J74B2CGa DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Subject:Cc:To: From:Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Unsubscribe-Post: List-Owner; bh=pVN1mqrOhYalxYFr7VReSIpfsAYguArpSUX3xTADh9w=; b=c1Bf0Azat45thJ 3VVJPnQGoJRCgfg3GAL82DUfsSZCU1bck9t6X3iTyN3X0Jl/izglbhqx/nQZCtqWLL4llP6rR5RuQ VH//vGFgr2/QVd0/UxxJOrtSWOtRZREWSVHaed7deifqzt5wGcUpl5azGabXMznTrhO8XcKGw0k/1 wV0ujRlr+DdT0w97rHF9v+AtmZMgsuUE90p+bD9kxZQQDwLZGivIMdkHmN1G9kqGe1ZGg5ceTxe/c Ym71ihYdmFVOcIQ97i2twOWXPRseDF68b8q4VOfB0nU+06wDFGx8YKcAni+IeThRmlExv4EvpBWjL CeTJOhaSlL25aajpRV4g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xJpCX-0000000DqIx-122R; Thu, 22 Oct 2026 09:35:09 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xJpCW-0000000DqIk-0FBn for linux-mediatek@bombadil.infradead.org; Thu, 22 Oct 2026 09:35:08 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:Content-Type :MIME-Version:References:In-Reply-To:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=pVN1mqrOhYalxYFr7VReSIpfsAYguArpSUX3xTADh9w=; b=N1Jev0D9j3hYUEXAF4zCucT4VC pDm9ASfcw9SEfwK6XsvHkTCaGgjXSviyzXtt5szsGqn5AeIO/a8eR8GAHoSCFA/AdV0Hj2XNynCkU dEnnAi6m+2B+XrKzlT1hFekTzpICaDEH7Uu0at74YK32AW7yDVgcCwd2HyuwieyMqWc8yVca1bjjQ sDlDKOXWnpr1cNSx1oQypdDvGWwo9OPp6xbkwSDiJWWcEb8Du5IIl9XRX5VuI1PBUaSwiXZD1qoiC ldHvNa90EfM5nGdyovxRjr11RyllPQ+mkEkYnr3XZe2svFAlX/Xd+Ed19CIjOSQOeDbrl2ezxnN/I /or9WBqg==; Received: from mail-wr1-x431.google.com ([2a00:1450:4864:20::431]) by desiato.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xJpCF-00000006lqL-1JT2 for linux-mediatek@lists.infradead.org; Thu, 22 Oct 2026 09:35:04 +0000 Received: by mail-wr1-x431.google.com with SMTP id ffacd0b85a97d-48c45111bebso1073333f8f.0 for ; Thu, 22 Oct 2026 02:34:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1792661688; x=1793266488; darn=lists.infradead.org; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=pVN1mqrOhYalxYFr7VReSIpfsAYguArpSUX3xTADh9w=; b=J74B2CGaiWBruj0UXipzLQp+NjfMg5Jvjbx3SzV4rgrTnrl6vo8q6WpMFdIKML4Ql+ o5JAGu7FA5SoPFcQl4edcISRBWMpQxYKjWeNhNDHE99aIG7/ZTg5cjDE1oJUEw9hQQdO g9aCylnXgvgYdhoOKWuBwXJ5m3Kzgf+9bQE4ZyPR3t8DWy4/RwsX7jfMSTrYlyPH1ZuQ 8qccVkNFewLUAenvsSctlrYteRjfXPgdgUXy4n1qUhbCFLR8iG6Oiw1cSHxaeclj94Gm QA5/MiOUyffqXFdXSCm/gflVSKtKizL6zk0Q0ebp+iJ27/B9hXLh7+24BP/EcHK+/JX2 2Vmw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1792661688; x=1793266488; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=pVN1mqrOhYalxYFr7VReSIpfsAYguArpSUX3xTADh9w=; b=1xLP6QoS/DVuqO3YAjQqP0smOqEP4lZLL1NMskksGlcG9rkInIej6jgNwx7TnaXOqZ ad6GHyBToYtY2GkkFPjOL6kAaRqinmS9kMSvjGcQCfBqyw28F5jOMtx6VCstHsbVRyVK Seezu9Pbzq04taqtJroRMGnreaU1gwQryWP0HHxMEM7s5t5GpY4+npfxnM/dgLak7OJk 2WtH8P3/ObRUTmWwuxlRG+vW2QrRt+qloqQ0v8bYMlOJceeLIWuzKxBUW4c1YIPxd2Wv urHBa2oW8k6T7ejv+ubQPFs7WXgFvZT2DBpzcjGVZzL+VKMZaO/8e9uPZf7l8+d2FX98 F/ew== X-Forwarded-Encrypted: i=1; AKwUvBzH5jyudGNgCsj814ae561DZG79Brf6uq4mlgd0M+ISfdq9q0rKZf9nwg9HWTiIOttBJPJh7v+qeKWTE8dYUw==@lists.infradead.org X-Gm-Message-State: AFq9FYK/sWQo+wKNBekKm8c0KeHq5u/9NZzx2Vzekr2lQx/6leOtUU6z RrVip24B/RF7PXzz95MOPtJmpfPRDxv7Ce1qazis5zPkGZN2hQtVaDxG X-Gm-Gg: AYBFou0lrFThigo2B5Pq9EWxH5JQRZoD+bx8ATJraWh7vrcqo+vCGtPo91XihbybnVM ynqV7kkL1AvmA1kZfPvJVkI2rsyLmT2moiaVRrPQTSGGojwu5e1WEO5iTBF2DUkaILhV2vf2+g7 1+TsyuKb8I5ZeP/mi9rV0L4zR07bXuu4PjGl6i5WU5XtTudfsmmel5vuRfzTQkHGLwANS5jl+pd KM/3Qn8fwkEEtnoubwUu+FC37iXF1/jk2Rnh3QnR9Y+YawGc2D9kCZD1A1eX6nG8J218VfPOUJr qlLWzI9wnyP1amv3dmNI6YHFUpAzRWGJhomLY4Klk1ZzKE6GQ/nPqDBWjIyfuVkEOHFrwKF2Cd8 PV2yyTAYaqehW+yK7mRcetuKXHt6nrVP8OZLoltdmP+Lz90SbWfj85L962BcGDo35AN+44tuTlv F2aevm7aK+C4Se89Qcpc8SU/nvzdb1h/jlMfO0HR8SwkVQ9zQ5+fT9lVYn8fJCOU+jvvcS6+y8d MZjuPck5aAIKMvN6GV6zhWmICBOWvtM4mWGMmqQCoIaQqQ4ToVJIHuY/Ikj1xdzKPPmXfahlYx3 QkPbnVgEqVZOANhM X-Received: by 2002:a05:6000:4806:b0:48b:451:4f19 with SMTP id ffacd0b85a97d-48e264e2f10mr9528690f8f.51.1792661687521; Thu, 22 Oct 2026 02:34:47 -0700 (PDT) Received: from pumpkin (82-69-66-36.dsl.in-addr.zen.co.uk. [82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e25828e72sm10420288f8f.26.2026.10.22.02.34.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Oct 2026 02:34:46 -0700 (PDT) Date: Thu, 22 Oct 2026 10:34:45 +0100 From: David Laight To: Fil Dunsky Cc: nbd@nbd.name, lorenzo@kernel.org, ryder.lee@mediatek.com, shayne.chen@mediatek.com, sean.wang@mediatek.com, matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, netdev@vger.kernel.org Subject: Re: [PATCH] wifi: mt76: dma: run threaded NAPI kthreads with SCHED_FIFO low priority Message-ID: <20261022103445.34cede9d@pumpkin> In-Reply-To: <179259275334.35963.15413466304986880275@gmail.com> References: <20261020-b4-mt76-napi-fifo-v1-1-ac8a24e2062a@gmail.com> <179259275334.35963.15413466304986880275@gmail.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261022_103453_164393_98F8F138 X-CRM114-Status: GOOD ( 18.95 ) X-Spam-Score: -0.2 (/) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" X-Spam-Status: No, score=-9.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Wed, 21 Oct 2026 17:25:53 +0300 Fil Dunsky wrote: > Adding netdev to Cc, as suggested on the GitHub mirror of this patch [1], > since it touches the scheduling policy of threaded NAPI kthreads. I had to fix the same thing for other NAPI threads when doing some tests that were receiving 'silly numbers' of RTP (aka very short UDP) packets. There is a similar problem with the softint threads. Softint callbacks drop form being the very highest priority items to things that really won't be run in a timely manner. David > > For context on why this is done in the driver rather than left to the > admin (chrt / sysfs): mt76 already does exactly this for its other > rx/status and tx workers (sched_set_fifo_low() for the usb and sdio > workers and for the tx worker), so the dma napi kthreads were the only > mt76 rx path left at SCHED_OTHER. A userspace chrt also has to race > the creation of the napi threads at boot and module reload. > > Numbers from the setup in the commit message (MT7621 + MT7612E as 5 GHz > client, 3 runs x 5 min each, ~200-280 Mbit/s rx with userspace load): > > stock: ~500 full-ring events / 5 min, watchdog > resets and MCU timeouts, occasional hard hang > this patch: 0 resets in 3 runs, rx 276-288 Mbit/s > stock + chrt -f 1: 0 resets in 3 runs, rx 249-273 Mbit/s > napi_threaded=0: 0 resets > rx ring 1024 (stock): 800-1300 full-ring events / run, more resets > > A similar restart pattern is reported on single-core MT7620 at much > lower rates [2], which fits CPU contention rather than throughput as the > trigger. > > [1] https://github.com/openwrt/mt76/pull/1164 > [2] https://github.com/openwrt/mt76/issues/457 > > Thanks, > Fil > >