From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-out02.uio.no (mail-out02.uio.no [IPv6:2001:700:100:8210::71]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id DB3823CB37 for ; Wed, 7 Feb 2024 06:57:03 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=ifi.uio.no; s=key2309; h=To:Date:Message-Id:Subject:Mime-Version:Content-Type:From:Sender :Reply-To:Cc:Content-Transfer-Encoding:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: In-Reply-To:References:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=Go0KFp/d9bxk/cqsyNql49lxmnQASk0ATSrHNiKiZ5U=; b=X3JEFL5C0F0Aq+8B8ts0iapugS ZGI8xkXOP6RO/3PKPnduDwS60a8nI6SBQJ/toYptbxtd9eKvD/58qqvfcNhBCGFTaPOR3np9awBJN 5+YLLgDtogom+yUctq8iwb70wkYSHmVk7vfjbGKUBwFIyXscRqwm5Bk1YH2Bm1uXcqNX9sWYgovV4 ltT2URTcnX3yv9IH+hANJjQVpsIioZxXznmUjbBiUdV4nvLnbZO2l7DbpUYhx3bQU3AMyYcsSnbGG v/XLT9PIRdBVq2zpSdTWzXfvbdG7VOJIy2qViaRgTneEpPc+07pfYd7JJT28QAwbk3ISiwC3UhMgY THH8N+aA==; Received: from mail-mx10.uio.no ([129.240.10.27]) by mail-out02.uio.no with esmtps (TLS1.2) tls TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 (Exim 4.96.2) (envelope-from ) id 1rXgY0-00FjW2-0z for bloat@lists.bufferbloat.net; Wed, 07 Feb 2024 12:57:00 +0100 Received: from collaborix.ifi.uio.no ([129.240.69.78] helo=smtpclient.apple) by mail-mx10.uio.no with esmtps (TLS1.2:ECDHE-ECDSA-AES256-GCM-SHA384:256) (Exim 4.96.2) (envelope-from ) id 1rXgXz-0002Ua-2F for bloat@lists.bufferbloat.net; Wed, 07 Feb 2024 12:57:00 +0100 From: Michael Welzl Content-Type: multipart/alternative; boundary="Apple-Mail=_D393B382-2EE4-440B-999D-A57ABB2475BA" Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.1\)) Message-Id: <1BAA689A-D44E-4122-9AD8-25F6D024377E@ifi.uio.no> Date: Wed, 7 Feb 2024 12:56:59 +0100 To: bloat@lists.bufferbloat.net X-Mailer: Apple Mail (2.3696.120.41.1.1) X-UiO-SPF-Received: Received-SPF: neutral (mail-mx10.uio.no: 129.240.69.78 is neither permitted nor denied by domain of ifi.uio.no) client-ip=129.240.69.78; envelope-from=michawe@ifi.uio.no; helo=smtpclient.apple; X-UiO-Spam-info: not spam, SpamAssassin (score=-4.6, required=5.0, autolearn=disabled, HTML_MESSAGE=0.001, KHOP_HELO_FCRDNS=0.4, T_SCC_BODY_TEXT_LINE=-0.01, UIO_MAIL_IS_INTERNAL=-5) X-UiO-Scanned: D93E421841D7767141BE7DA763B4D64533B43477 X-UiOonly: D65B2DA01E3428A123342F662D7508DACD833491 Subject: [Bloat] Trying to *really* understand Linux pacing X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 07 Feb 2024 11:57:04 -0000 --Apple-Mail=_D393B382-2EE4-440B-999D-A57ABB2475BA Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Dear de-bloaters of buffers, Esteemed experts of low delay and pacing! I have no longer been satisfied with high-level descriptions of how = pacing works in Linux, and how it interacts with TSQ (I=E2=80=99ve seen = some, in various papers, over the years) - but I wanted to REALLY = understand it. So, I have dug through the code. I documented this experience here: = https://docs.google.com/document/d/1-uXnPDcVBKmg5krkG5wYBgaA2yLSFK_kZa7xGD= Wc7XU/edit?usp=3Dsharing = but it has some holes and may have mistakes. Actually, my main problem is that I don=E2=80=99t really know what goes = on when I configure a larger IW=E2=80=A6 things seem to get quite = =E2=80=9Coff=E2=80=9D there. Why? Anyone up for solving that riddle? = ;-) (see the tests I documented towards the end of the document) Generally, if someone who has their hands on files such as tcp_output.c = all the time could take a look, and perhaps =E2=80=9Cfill=E2=80=9D my = holes, or improve anything that might be wrong, that would be fantastic! = I think that anyone should be allowed to comment and make suggestions = in this doc. MANY thanks to whoever finds the time to take a look ! Cheers, Michael --Apple-Mail=_D393B382-2EE4-440B-999D-A57ABB2475BA Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 Dear = de-bloaters of buffers,
Esteemed experts of low delay and = pacing!

I have = no longer been satisfied with high-level descriptions of how pacing = works in Linux, and how it interacts with TSQ (I=E2=80=99ve seen some, = in various papers, over the years) - but I wanted to REALLY understand = it. So, I have dug through the code.

I documented this experience = here:
https://docs.google.com/document/d/1-uXnPDcVBKmg5krkG5wYBgaA2yL= SFK_kZa7xGDWc7XU/edit?usp=3Dsharing
but it has = some holes and may have mistakes.

Actually, my main problem is that I = don=E2=80=99t really know what goes on when I configure a larger IW=E2=80=A6= things seem to get quite =E2=80=9Coff=E2=80=9D there. Why? Anyone up = for solving that riddle?  ;-)
(see the tests I = documented towards the end of the document)

Generally, if someone who has their = hands on files such as tcp_output.c all the time could take a look, and = perhaps =E2=80=9Cfill=E2=80=9D my holes, or improve anything that might = be wrong, that would be fantastic!   I think that anyone should be = allowed to comment and make suggestions in this doc.

MANY thanks to whoever = finds the time to take a look !

Cheers,
Michael

= --Apple-Mail=_D393B382-2EE4-440B-999D-A57ABB2475BA--