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 A98D1C4332F for ; Thu, 9 Nov 2023 22:07:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345424AbjKIWHv (ORCPT ); Thu, 9 Nov 2023 17:07:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51096 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234775AbjKIWHm (ORCPT ); Thu, 9 Nov 2023 17:07:42 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2D3AF1FF6 for ; Thu, 9 Nov 2023 14:06:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1699567614; 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=vTCrETe33lMmrS3iamQBvHr88tXqZxqdutyVeBzQWY0=; b=ESjqQoMuZEf4gIxXEiaJJ7sDoiAjo3l2NFYmB83eQfXGW0kOGaKi/i+rtfg/vKlKLvh/Lv 1uufcebAc91N8Jcf6rO7HnWbHtRNITJzsJdi5/KPuu5vjaijuQzWxCjruJIUZB0zrMfPAf slrxZiH9Ut3Tm+dfxFaCYvRy8oIGMLk= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-623-Goh8HWQaMEyXDt1PmNGdJw-1; Thu, 09 Nov 2023 17:06:50 -0500 X-MC-Unique: Goh8HWQaMEyXDt1PmNGdJw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 0CE3C1C068C1; Thu, 9 Nov 2023 22:06:50 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.42.28.13]) by smtp.corp.redhat.com (Postfix) with ESMTP id 38367C1290F; Thu, 9 Nov 2023 22:06:49 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <6fadc6aa-4078-4f12-a4c7-235267d6e0b1@auristor.com> References: <6fadc6aa-4078-4f12-a4c7-235267d6e0b1@auristor.com> <20231109154004.3317227-1-dhowells@redhat.com> <20231109154004.3317227-2-dhowells@redhat.com> To: Jeffrey E Altman Cc: dhowells@redhat.com, Marc Dionne , linux-afs@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 01/41] rxrpc: Fix RTT determination to use PING ACKs as a source MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <3327952.1699567608.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Thu, 09 Nov 2023 22:06:48 +0000 Message-ID: <3327953.1699567608@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I'm going to drop this patch from this series for now and send it separate= ly. > I do not believe the ack_reason matters within rxrpc_input_ack(). As lon= g as > the acked_serial is non-zero, > rxrpc_complete_rtt_probe() can be called to attempt to compute an RTT. = If > there is an exact match for the > acked_serial then an RTT can be computed and if acked_serial is later th= an the > pending rtt probe, the probe > can be abandoned with the following caveats. > = > 1. Receiving an acked_serial that is later than the serial of the > transmitted probe indicates that a packet > transmitted after the probe was received first. Or that reordering > of the transmitted packets occurred. > Or that the probe was never received by the peer; or that the peer's > response to the probe was lost in > transit. > 2. The serial number namespace is unsigned 32-bit shared across all of > the call channels of the associated > rx connection. As the serial numbers will wrap the use of after() > within rxrpc_complete_rtt_probe to > compare their values is questionable. If serial numbers will be > compared in this manner then they > need to be locally tracked and compared as unsigned 64-bit values > where only the low 32-bits are > transmitted on the wire and any wire serial number equal to zero is > ignored. I do ignore ack.serial =3D=3D 0 for this purpose. I'm not sure how expanding it internally to 64-bits actually helps since t= he upper 32 bits is not visible to the peer. David