From nobody Sun Feb 8 06:05:42 2026 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 C1469C636CC for ; Wed, 8 Feb 2023 10:29:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231477AbjBHK3R (ORCPT ); Wed, 8 Feb 2023 05:29:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37638 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230203AbjBHK2w (ORCPT ); Wed, 8 Feb 2023 05:28:52 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 67A0B4672A for ; Wed, 8 Feb 2023 02:28:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675852082; 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=AIbGFXSEGrcouEuIniWxwMqD+I+3i7zmAP6fRARvEuo=; b=eZ89A7DBEH3V/4ue2J/8UWZfrBsfAX5tAEkVdpTxpUfxim6AHPS8dOwvgGU93kxXFjcVKQ fitwXOX7TFKr+njnXy5gTG0KDkJ4Sfxvbh+Vz1+oP5cvEbaJgBrQdEEPuSoaQQIfbFmkJI MAT4EuaxJ2aknCOEpRhJ1Qt0p4Ltrj8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-670-_iwab9PJNXWBQVklYDQKwA-1; Wed, 08 Feb 2023 05:28:01 -0500 X-MC-Unique: _iwab9PJNXWBQVklYDQKwA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D773D8030D0; Wed, 8 Feb 2023 10:28:00 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.24]) by smtp.corp.redhat.com (Postfix) with ESMTP id B71542166B2B; Wed, 8 Feb 2023 10:27:59 +0000 (UTC) From: David Howells To: netdev@vger.kernel.org Cc: David Howells , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Marc Dionne , linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH net-next 4/4] rxrpc: Reduce unnecessary ack transmission Date: Wed, 8 Feb 2023 10:27:50 +0000 Message-Id: <20230208102750.18107-5-dhowells@redhat.com> In-Reply-To: <20230208102750.18107-1-dhowells@redhat.com> References: <20230208102750.18107-1-dhowells@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" rxrpc_recvmsg_data() schedules an ACK to be transmitted every time at least two packets have been consumed and any time it runs out of data and would return -EAGAIN to the caller. Both events may occur within a single loop, however, and if the I/O thread is quick enough it may send duplicate ACKs. The ACKs are sent to inform the peer that more space has been made in the local Rx window, but the I/O thread is going to send an ACK every couple of DATA packets anyway, so we end up sending a lot more ACKs than we really need to. So reduce the rate at which recvmsg() schedules ACKs, such that if the I/O thread sends ACKs at its normal faster rate, recvmsg() won't actually schedule ACKs until the Rx flow stops (call->rx_consumed is cleared any time we transmit an ACK for that call, resetting the counter used by recvmsg). Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org --- net/rxrpc/recvmsg.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c index 50d263a6359d..76eb2b9cd936 100644 --- a/net/rxrpc/recvmsg.c +++ b/net/rxrpc/recvmsg.c @@ -137,7 +137,7 @@ static void rxrpc_rotate_rx_window(struct rxrpc_call *c= all) /* Check to see if there's an ACK that needs sending. */ acked =3D atomic_add_return(call->rx_consumed - old_consumed, &call->ackr_nr_consumed); - if (acked > 2 && + if (acked > 8 && !test_and_set_bit(RXRPC_CALL_RX_IS_IDLE, &call->flags)) rxrpc_poke_call(call, rxrpc_call_poke_idle); }