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]) by passt.top (Postfix) with ESMTP id 8A7D65A026A for ; Mon, 13 Feb 2023 02:22:16 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1676251333; 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=WpGY8aSLOA3H3ZwWy+gp8Yhpj98qRixREm0kBB44alw=; b=OKubpfI//pmXtWemwK+sl1ICP8pRIFZeVeZXFNagZyJrdCZaDUw9jrnA2IoylkMnIeQ5Es kKGKGnGs9IZxwZGyJxI70Fxxg/gfG5QZqaVRCUrYRHCZQuVQGHknp0iW6rTnOTatFGj1Y0 JDIiZLW9ObI4kj6Vf0bVU0c9iJxuDs4= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-198-VY6FcgwRMmeCZYOoYty2Pg-1; Sun, 12 Feb 2023 20:22:09 -0500 X-MC-Unique: VY6FcgwRMmeCZYOoYty2Pg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C6FF829AA39A; Mon, 13 Feb 2023 01:22:08 +0000 (UTC) Received: from maya.cloud.tilaa.com (unknown [10.33.32.3]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A7117400DFCF; Mon, 13 Feb 2023 01:22:08 +0000 (UTC) Date: Mon, 13 Feb 2023 02:14:25 +0100 From: Stefano Brivio To: David Gibson Subject: Re: [PATCH v3 00/18] RFC: Unify and simplify tap send path Message-ID: <20230213021425.1d5edd76@elisabeth> In-Reply-To: <20230126002133.7a8eec98@elisabeth> References: <20230106004322.985665-1-david@gibson.dropbear.id.au> <20230124222043.281ef58c@elisabeth> <20230126002133.7a8eec98@elisabeth> Organization: Red Hat MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-ID-Hash: G7U3VOCDCHNWORNQV7HE4UPTBPSF6HHA X-Message-ID-Hash: G7U3VOCDCHNWORNQV7HE4UPTBPSF6HHA X-MailFrom: sbrivio@redhat.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: passt-dev@passt.top X-Mailman-Version: 3.3.3 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Thu, 26 Jan 2023 00:21:33 +0100 Stefano Brivio wrote: > On Wed, 25 Jan 2023 14:13:44 +1100 > David Gibson wrote: > > > On Tue, Jan 24, 2023 at 10:20:43PM +0100, Stefano Brivio wrote: > > > On Fri, 6 Jan 2023 11:43:04 +1100 > > > David Gibson wrote: > > > > > > > Although we have an abstraction for the "slow path" (DHCP, NDP) guest > > > > bound packets, the TCP and UDP forwarding paths write directly to the > > > > tap fd. However, it turns out how they send frames to the tap device > > > > is more similar than it originally appears. > > > > > > > > This series unifies the low-level tap send functions for TCP and UDP, > > > > and makes some clean ups along the way. > > > > > > > > This is based on my earlier outstanding series. > > > > > > For some reason, performance tests consistently get stuck (both TCP and > > > UDP, sometimes throughput, sometimes latency tests) with this series, > > > and not without it, but I don't see any possible relationship with that. > > > > Drat, I didn't encounter that. Any chance you could bisect to figure > > out which patch specifically seems to trigger it? > > [...] > > > I wonder if this could be related to the stalls I'm debugging, > > although those didn't appear on the perf tests and also occur on > > main. I have now discovered they seem to be masked by large socket > > buffer sizes - more info at https://bugs.passt.top/show_bug.cgi?id=41 > > Maybe the subsequent failures (or even this one) could actually be > related, and triggered somehow by some change in timing. I'm still > clueless at the moment. This turned out to be a combination of three different issues: - left-over patches in my local qemu tree (and build) trying to address the virtio-net TX hang ultimately fixed by kernel commit d71ebe8114b4 ("virtio-net: correctly enable callback during start_xmit"). I'm using the latest upstream now, clean - the issue you reported at https://bugs.passt.top/show_bug.cgi?id=41, I just posted a patch for it - the issue introduced by "tcp: Combine two parts of pasta tap send path together", patch also posted With these three sorted, finally I could apply this series! Apologies for the delay. -- Stefano