From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id A72DFA00C3; Tue, 20 Sep 2022 09:12:59 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 91D9841156; Tue, 20 Sep 2022 09:12:59 +0200 (CEST) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by mails.dpdk.org (Postfix) with ESMTP id 5207840DFB for ; Tue, 20 Sep 2022 09:12:58 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1663657977; 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=8ZOwI83R41OpSRKaIX9LQ3VURLxI/VOL46wS4XPjcc8=; b=SrOFbqnL3U4wUKwu1HZxskMB2rdN5ii9FI+LiNZWgEEMtn6Jk5NatJbry72W5VmmHWoOhp dQFuGK/l1WdfGEA5xWDum8aDFAbOpZ718vZmFtec5sNP/GSry491Cup/NJNqHhBnfCjTXB qhOUYRzaHbE0GITzDyaEuP549MWXRAw= 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-653-oGZZrbzLNwiAPHpwZHCZtA-1; Tue, 20 Sep 2022 03:12:54 -0400 X-MC-Unique: oGZZrbzLNwiAPHpwZHCZtA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 57A603C02B7F; Tue, 20 Sep 2022 07:12:54 +0000 (UTC) Received: from [10.39.208.16] (unknown [10.39.208.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5129A1759F; Tue, 20 Sep 2022 07:12:53 +0000 (UTC) Message-ID: <8be85d76-2671-57e1-58c2-30070428a66c@redhat.com> Date: Tue, 20 Sep 2022 09:12:51 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH] vhost: use try_lock in rte_vhost_vring_call To: "Liu, Changpeng" , Stephen Hemminger Cc: "dev@dpdk.org" , "Xia, Chenbo" References: <20220906022225.17215-1-changpeng.liu@intel.com> <20220906141538.7aa0876b@hermes.local> From: Maxime Coquelin In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On 9/7/22 02:40, Liu, Changpeng wrote: > > >> -----Original Message----- >> From: Stephen Hemminger >> Sent: Wednesday, September 7, 2022 5:16 AM >> To: Liu, Changpeng >> Cc: dev@dpdk.org; Maxime Coquelin ; Xia, >> Chenbo >> Subject: Re: [PATCH] vhost: use try_lock in rte_vhost_vring_call >> >> On Tue, 6 Sep 2022 10:22:25 +0800 >> Changpeng Liu wrote: >> >>> Note that this function is in data path, so the thread context >>> may not same as socket messages processing context, by using >>> try_lock here, users can have another try in case of VQ's access >>> lock is held by `vhost-events` thread. >>> >>> Signed-off-by: Changpeng Liu >>> --- >>> lib/vhost/vhost.c | 6 +++++- >>> 1 file changed, 5 insertions(+), 1 deletion(-) >>> >>> diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c >>> index 60cb05a0ff..072d2acb7b 100644 >>> --- a/lib/vhost/vhost.c >>> +++ b/lib/vhost/vhost.c >>> @@ -1329,7 +1329,11 @@ rte_vhost_vring_call(int vid, uint16_t vring_idx) >>> if (!vq) >>> return -1; >>> >>> - rte_spinlock_lock(&vq->access_lock); >>> + if (!rte_spinlock_trylock(&vq->access_lock)) { >>> + VHOST_LOG_CONFIG(dev->ifname, DEBUG, >>> + "failed to kick guest, virtqueue busy.\n"); >>> + return -1; >>> + } >>> >> >> If it is a race, logging a message is not a good idea; the log will fill >> with this noise. >> >> Instead make it statistic that can be seen by xstats. > It's a DEBUG log, users can't see it in practice. > Having an xstat would enable live debugging & post-mortem analysis. You can have both the stats and the debug log. Regards, Maxime