From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CC8D7361677 for ; Fri, 16 Jan 2026 11:00:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768561209; cv=none; b=KxwHp1zjGnS3x/nEJ7nsp5PJwA3hQPm76aopzEcTY9XYwhbCWYyKW0862EDPYeHR4fzTk7qCximV7Kpf3ANgCK6t4fTtAFK5zub5Fq2IyH7oWt9NKzLtHM9mGkly7GbgdM8H1AuAREv81yg8MeL5Fb7gU+LnIvZZDlJoHhuWBr4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768561209; c=relaxed/simple; bh=vksLTZkUWWrOReeJ5m+TZEyTyRNJeH3pyvTWA6g0a/g=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=YAt9MU5qR6gak582q43pcCs7dj6MYFtRDETLTOxhHNBTwfPHCzLinl14mrD3Qb8My3OKaDn2EcHbxOL6XGFemAXn7oCpGuZiVVLqEdCcoSafKUzmguRl8gE8bbcLS6olPmheBd4BFTI/HwR7j+NMCxZMXh0EUasghtc4ZC/79TY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=FgXFXUMo; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=f+jdHZr/; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="FgXFXUMo"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="f+jdHZr/" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1768561206; 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: in-reply-to:in-reply-to:references:references; bh=9DcHDZID0O5xO6b4wZGyRTdWKoELa3pTt4TtE2mtQ60=; b=FgXFXUMoQuk7jOEqM5rvEE3VfyKVeTu8+CaovjEnn2pg/L3a58qakVecP0qHNS28PZ3MV/ viritmjaXVFX2REkg3Ib7OCGwm5MbSdU0bXAKjamVqCe7xgZfH++dXFPZ0qYzuQmUO5yF3 7mgVF/5v826ly3gfecsrHEe1rHX/sMg= Received: from mail-ej1-f71.google.com (mail-ej1-f71.google.com [209.85.218.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-652-3_XLJ3V_P5iCmYyKaRFbsg-1; Fri, 16 Jan 2026 06:00:05 -0500 X-MC-Unique: 3_XLJ3V_P5iCmYyKaRFbsg-1 X-Mimecast-MFC-AGG-ID: 3_XLJ3V_P5iCmYyKaRFbsg_1768561204 Received: by mail-ej1-f71.google.com with SMTP id a640c23a62f3a-b8711b467f3so485425466b.1 for ; Fri, 16 Jan 2026 03:00:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1768561204; x=1769166004; darn=vger.kernel.org; h=mime-version:message-id:date:references:in-reply-to:subject:cc:to :from:from:to:cc:subject:date:message-id:reply-to; bh=9DcHDZID0O5xO6b4wZGyRTdWKoELa3pTt4TtE2mtQ60=; b=f+jdHZr/6KcG9Ptvcjn3/H1dJdOTbghHSHX5aXcNon/B6i0Z6yokuimjj8fYl4GApj m62VV0a5QtXfKL4aMx0R2e6Ziao0Uq0bsui10dN3pCszyEGwsvprMpoBEXnMQd+foTmb 7fiqUxwYY8yKl/kz6cdhSGSi5b16ui71INjBxdr5Jlm7kimQYPdTVKzsgAopk6qLoITQ Xm1Hzl+MemMJuIAUr5qoDygxXe14nCrz/ce1LUQJQpcSJ1Ifm3lsGnu0j7WLy5Q479DJ 3gK5EigDn3A1rOW7GeBeCwECOnE5W22WskFTeXyzJVyVeGclYQqTQKuWP2E/IYX4Z3bE 8xBw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1768561204; x=1769166004; h=mime-version:message-id:date:references:in-reply-to:subject:cc:to :from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=9DcHDZID0O5xO6b4wZGyRTdWKoELa3pTt4TtE2mtQ60=; b=tIf+pP93L3jRNqU2A9xZ+CItLULY9qfQN9PeIPro/Qovj72tuhK10d7S37vJlvjXmP JMMA3wEeaKAQS6DY6UTCTEB0tb9aH43NOW+vnj+XAcRjrTYsyA+za7vY0t9DCzcWzijE pNyIu2t2CAsLZE+i9iyd0Wv89Tvj8xthmoXaBuX3V/HiuY7Yn9M1lK88pjCEAtKbcMfW IUt8EcGtjpD3hC0lXVitG+XFSl9QSMPwoUnd+o6IZ603SAilEN+4yKeRoZNVNY+XJBki 4jdPgYFGmxsU1voQWMFnEYXOpZx/UYkNXkZyRB3dBa5tQHiL2Ym7E8uZSzYfVtTANhLC QYHQ== X-Gm-Message-State: AOJu0YwxyMltyC6SdSXuM82weSsj8Wy+fcZNe33Q8TDvCudHN+EVJ5Uq DmziyfpIqxFjFdgNkNZXn8VNYZFz9LzYMefYQg4V9DNKQ0GsXo41rfE4OhxYf13e1Q2pFAuU7ca ORn7Q624gbYE48sOKAp/SpUKD/zuWnBMJCJN4guClyP5TzTRuRuVCDA== X-Gm-Gg: AY/fxX7fNHNHznotlSjr5LgqlmpPxULJvGQUJTE1wvlUjkhjOEMN4Yr6ahIiKGW0Jai CphmL73Yauyi+3eDQG53+IFmKrAL3vm4CHgt7/OaQtr5+Q9P1ULXHHzDV7ncKk63uGHqPzoKwpq j1KZezvu1CJfQTgb4SwI7oBAM7EthcJnd8SwzWXTxHih0iqUYUo8K4Wmkz1b1UFaEJGBz5wNnZ9 WcSD9qilrG9SgAQ6t44ewMo5RQyN9w28a7h3hnLgiDva0paCemabGeOErnXbXzmZQtuCLEFHYGn QYLxOBXVZpcfBa4wMXwyMLmeA6nyMe6fj+6VPQiFLOldYEQPbfVU2uzldQ1FZkCAZNImUHSyp+x IheiQqa4ovem0cpDgCD3u9zY6pshqVVJKKQ0m X-Received: by 2002:a17:907:a48:b0:b87:672c:4108 with SMTP id a640c23a62f3a-b879385870amr281457466b.4.1768561204245; Fri, 16 Jan 2026 03:00:04 -0800 (PST) X-Received: by 2002:a17:907:a48:b0:b87:672c:4108 with SMTP id a640c23a62f3a-b879385870amr281454866b.4.1768561203767; Fri, 16 Jan 2026 03:00:03 -0800 (PST) Received: from alrua-x1.borgediget.toke.dk (alrua-x1.borgediget.toke.dk. [2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b87959c9b5bsm208337266b.44.2026.01.16.03.00.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 16 Jan 2026 03:00:03 -0800 (PST) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id AA04B408DF9; Fri, 16 Jan 2026 12:00:00 +0100 (CET) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Jesper Dangaard Brouer , netdev@vger.kernel.org Cc: bpf@vger.kernel.org, Eric Dumazet , "David S. Miller" , Jakub Kicinski , Paolo Abeni , carges@cloudflare.com, kernel-team@cloudflare.com Subject: Re: [PATCH net-next v1] net: sched: sfq: add detailed drop reasons for monitoring In-Reply-To: <1bbbb306-d497-4143-a714-b126ecc41a06@kernel.org> References: <176847978787.939583.16722243649193888625.stgit@firesoul> <1bbbb306-d497-4143-a714-b126ecc41a06@kernel.org> X-Clacks-Overhead: GNU Terry Pratchett Date: Fri, 16 Jan 2026 12:00:00 +0100 Message-ID: <87ms2dzutr.fsf@toke.dk> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Jesper Dangaard Brouer writes: > Hi Eric, > > I need an opinion on naming for drop_reasons below. > > On 15/01/2026 13.23, Jesper Dangaard Brouer wrote: >> Add specific drop reasons to SFQ qdisc to improve packet drop observability >> and monitoring capabilities. This change replaces generic qdisc_drop() >> calls with qdisc_drop_reason() to provide granular metrics about different >> drop scenarios in production environments. >> >> Two new drop reasons are introduced: >> >> - SKB_DROP_REASON_QDISC_MAXFLOWS: Used when a new flow cannot be created >> because the maximum number of flows (flows parameter) has been >> reached and no free flow slots are available. >> >> - SKB_DROP_REASON_QDISC_MAXDEPTH: Used when a flow's queue length exceeds >> the per-flow depth limit (depth parameter), triggering either tail drop >> or head drop depending on headdrop configuration. > > I noticed commit 5765c7f6e317 ("net_sched: sch_fq: add three > drop_reason") (Author: Eric Dumazet). > > SKB_DROP_REASON_FQ_BAND_LIMIT: Per-band packet limit exceeded > SKB_DROP_REASON_FQ_HORIZON_LIMIT: Packet timestamp too far in future > SKB_DROP_REASON_FQ_FLOW_LIMIT: Per-flow packet limit exceeded > > Should I/we make SKB_DROP_REASON_QDISC_MAXDEPTH specific for SFQ ? > Like naming it = SKB_DROP_REASON_SFQ_MAXDEPTH ? > > Currently SKB_DROP_REASON_QDISC_MAXDEPTH is only used in SFQ, but it > might be usable in other qdisc as well. Except that I noticed the > meaning of SKB_DROP_REASON_FQ_FLOW_LIMIT which is basically the same. > This made me think that perhaps I should also make it qdisc specific. > I'm considering adding a per-flow limit to fq_codel as I'm seeing prod > issues with the global 10240 packet limit. This also need a similar flow > depth limit drop reason. I'm undecided which way to go, please advice. IMO, we should be reusing drop reasons where it makes sense (so s/FQ/QDISC/ SKB_DROP_REASON_FQ_FLOW_LIMIT), but not sure if these are considered UAPI (i.e., can we change the name of the existing one)? -Toke