From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-x42d.google.com (mail-wr1-x42d.google.com [IPv6:2a00:1450:4864:20::42d]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 5BB8F3B29E for ; Fri, 16 Dec 2022 10:16:39 -0500 (EST) Received: by mail-wr1-x42d.google.com with SMTP id bx10so2877213wrb.0 for ; Fri, 16 Dec 2022 07:16:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=BcaKrcjiHEUPWYTpQ7n++ytWYOZ+LT5/5QD5UBttA1M=; b=KdMtc/20CNwh8g0qu9N4zztO+qJ/AVn4AEn04e8++FaYIrkMrlwgRTqxvhb++iVyWr aSABnmye0x9yfuMJ5KpIelTAW8m8gUknJj2MCC5Pj6B6w1xlsDPukD8SIIa8n8mBZRol 9IrJDZr9Xwjkq4J6aWOQMExAKWutZ4hYPdVl+ii4ahLXDQjaCEfzuykqac3SsiOJtgE+ diKhQl+dFmD+PILf54Pyf1g3Ng7CsVmlz9A4zAd0/JV57/3+BTWZ3up0RRyvElVsVMFX ElCgNPNYncPtd1J4YeuLj7qzJgvejYY+h8ZUvBCyNW+4OOz+AYRQSmTcEf9dG4/XJYpm OKkg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=BcaKrcjiHEUPWYTpQ7n++ytWYOZ+LT5/5QD5UBttA1M=; b=hOQ9ca+ojrtMloGhJs//HzW8l197ai3xw3Fhkk5KNfgkq98dnbZFnDb+EBajsQfII0 w0hkvwI6sLHUV+0OoYfpBi3TtkRfAZGyx5qwvTCUOwiwasO1hSJvwIu8+yMZhMWbyN9j tSiLtQzRK7LgI8UXYScg1VokOmy56gqevyQoruN0y2ZU7nUesmeIL8n6mWMNLyLCKvSa SwfB46rWDUs/E0Hy48+3Di0Y9NWA1w4lB5lLUYdiRu3efm/jwvnZekWu/+2QgwSCzYxt hJOm30kNVoqdrT2cjPh2z02zFqRUuDeLwzlywTCHsxuQmX8IzCTS4vcT4Wb6LjGC5Mwb mvmg== X-Gm-Message-State: ANoB5pmsMhY2ouN3+Y6zkSnjvPNnKtr0x+0iXv5sgsf+d7LraaZ4RlKq cfJnf6MUneZg2Sqk4HCYRcHk/DB7AkwevtJK8e3uaqT9 X-Google-Smtp-Source: AA0mqf6spkYRyTeKXyxKpRy9iBiYji5HL4aaQFrJ2qu1kzgK0KoeINzsLsRrWT2oe12S8UR7ijmO/8WhZId7dLVg4hk= X-Received: by 2002:a5d:510c:0:b0:242:82f5:fe65 with SMTP id s12-20020a5d510c000000b0024282f5fe65mr4286936wrt.688.1671203797660; Fri, 16 Dec 2022 07:16:37 -0800 (PST) MIME-Version: 1.0 References: <87wn6sb5ap.fsf@toke.dk> <87a63nbdm6.fsf@toke.dk> In-Reply-To: <87a63nbdm6.fsf@toke.dk> From: Dave Taht Date: Fri, 16 Dec 2022 07:16:25 -0800 Message-ID: To: libreqos Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: [LibreQoS] Fwd: you guys got any favorite flame graphs? X-BeenThere: libreqos@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Many ISPs need the kinds of quality shaping cake can do List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 16 Dec 2022 15:16:39 -0000 ---------- Forwarded message --------- From: Toke H=C3=B8iland-J=C3=B8rgensen Dave Taht writes: > Is it a delusional dream to want to poll tc -s qdisc show of 40k > instances of cake on a htb tree every 10ms? > > presently 10k takes about 290us (locked to one cpu), and I have no > idea what to look for while doing that. So that's dumping all of them sequentially? In a single dump call from the root, or multiple calls? Assuming sequentially, that works out to 29 nanoseconds per instance, which I'd say that was pretty good... Looks like Eric already optimised the stat dumping in: edb09eb17ed8 ("net: sched: do not acquire qdisc spinlock in qdisc/class stats dump") So it doesn't take the qdisc lock at all, unless you're also dumping the class (per-flow) stats in the case of sch_cake. As a side note, this may mean that the cake stats can suffer from load tearing on 32-bit systems, since it's just doing a regular unprotected read of everything, including the 64-bit counters... -Toke --=20 This song goes out to all the folk that thought Stadia would work: https://www.linkedin.com/posts/dtaht_the-mushroom-song-activity-69813666656= 07352320-FXtz Dave T=C3=A4ht CEO, TekLibre, LLC