From nobody Fri Dec 19 04:57:57 2025 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 3388B193091 for ; Wed, 4 Dec 2024 07:49:24 +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=1733298566; cv=none; b=gF/M/6hz3vP0XFP32wNQpjEDaaBsKWTEvWDUCuXdnj+XmVp0pI+izOM0aoypCrXd92QCTxRStlwGJFhcZNKGJfll6hH1rF6hrs2vDNkPnHvQB5wsOYNguNN4gxWwE20PiGEKbe/D/QQGUD4PvoeVyTsSDNv606L0j+y6m9TpLEk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733298566; c=relaxed/simple; bh=YtjjrJglzNbaWY3oR5O84SLCh/26+LOHepc0+fkoFTo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mfVs5IRLX6RdLa9Pm37eVdYLKhdL+0SEkCzKaMFv2Z2m1B+QP62Sqc0YYFONBctrRDQSsXxnenWgodsFI1dFQg3aBsFXTE6UeGjaKVDH3w//VmH5y1o6izvPYIrynoxU+3I+GNPFHp6cLAFhH6jScEJXaqjZtr+HsRPML8SQt8s= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none 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=i6ZzN4Di; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none 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="i6ZzN4Di" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1733298564; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rF+8sPKxES4A1AKWrEyikFQcOwxRXaA9QVPagIN61Ew=; b=i6ZzN4DioMyCYAWANKTSQv5CIlxoj0frc2/14ttgp8ZhaAvAL+bEuYkfCAba/jZ72pRHyK J8FtP56505bLY9u6wmwIzrDOY3RSk68xPfyJOZS7IyuWPBpQhz4xiZanEcDrnEjSTdPXrI GtStpaTgxqAeFXAfxL3UVATzfT+cqOA= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-130-yxjoyEIPObS8NWWEPyEmgA-1; Wed, 04 Dec 2024 02:49:19 -0500 X-MC-Unique: yxjoyEIPObS8NWWEPyEmgA-1 X-Mimecast-MFC-AGG-ID: yxjoyEIPObS8NWWEPyEmgA Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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 mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8F96D1956053; Wed, 4 Dec 2024 07:49:17 +0000 (UTC) Received: from warthog.procyon.org.uk.com (unknown [10.42.28.48]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id A29BB3000199; Wed, 4 Dec 2024 07:49:14 +0000 (UTC) From: David Howells To: netdev@vger.kernel.org Cc: David Howells , Marc Dionne , Yunsheng Lin , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org, Simon Wilkinson Subject: [PATCH net-next v2 29/39] rxrpc: Fix the calculation and use of RTO Date: Wed, 4 Dec 2024 07:46:57 +0000 Message-ID: <20241204074710.990092-30-dhowells@redhat.com> In-Reply-To: <20241204074710.990092-1-dhowells@redhat.com> References: <20241204074710.990092-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Content-Type: text/plain; charset="utf-8" Make the following changes to the calculation and use of RTO: (1) Fix rxrpc_resend() to use the backed-off RTO value obtained by calling rxrpc_get_rto_backoff() rather than extracting the value itself. Without this, it may retransmit packets too early. (2) The RTO value being similar to the RTT causes a lot of extraneous resends because the RTT doesn't end up taking account of clearing out of the receive queue on the server. Worse, responses to PING-ACKs are made as fast as possible and so are less than the DATA-requested-ACK RTT and so skew the RTT down. Fix this by putting a lower bound on the RTO by adding 100ms to it and limiting the lower end to 200ms. Fixes: c410bf01933e ("rxrpc: Fix the excessive initial retransmission timeo= ut") Fixes: 37473e416234 ("rxrpc: Clean up the resend algorithm") Signed-off-by: David Howells Suggested-by: Simon Wilkinson cc: Marc Dionne cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: linux-afs@lists.infradead.org cc: netdev@vger.kernel.org --- net/rxrpc/call_event.c | 3 ++- net/rxrpc/rtt.c | 2 +- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c index f71773b18e22..4390c97e3ba6 100644 --- a/net/rxrpc/call_event.c +++ b/net/rxrpc/call_event.c @@ -103,7 +103,8 @@ void rxrpc_resend(struct rxrpc_call *call, rxrpc_serial= _t ack_serial, bool ping_ .now =3D ktime_get_real(), }; struct rxrpc_txqueue *tq =3D call->tx_queue; - ktime_t lowest_xmit_ts =3D KTIME_MAX, rto =3D ns_to_ktime(call->peer->rto= _us * NSEC_PER_USEC); + ktime_t lowest_xmit_ts =3D KTIME_MAX; + ktime_t rto =3D rxrpc_get_rto_backoff(call->peer, false); bool unacked =3D false; =20 _enter("{%d,%d}", call->tx_bottom, call->tx_top); diff --git a/net/rxrpc/rtt.c b/net/rxrpc/rtt.c index e0b7d99854b4..3f1ec8e420a6 100644 --- a/net/rxrpc/rtt.c +++ b/net/rxrpc/rtt.c @@ -27,7 +27,7 @@ static u32 __rxrpc_set_rto(const struct rxrpc_peer *peer) =20 static u32 rxrpc_bound_rto(u32 rto) { - return umin(rto, RXRPC_RTO_MAX); + return clamp(200000, rto + 100000, RXRPC_RTO_MAX); } =20 /*