From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-97.freemail.mail.aliyun.com (out30-97.freemail.mail.aliyun.com [115.124.30.97]) (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 0CBAB54720 for ; Thu, 20 Jun 2024 07:34:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.97 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718868894; cv=none; b=aidBQGUXMUoYKpt0xd1prTZs4N8fM+5FIslg2GgVGPr+G6b0twvx7dM1wnwwRVrZwGk0MAJcMlSh8jYAr06IXc7qPgOSaJLAWEq+K21Ehnt9/38m3mJ8xpDHXp8KF7jdtzyXvvekRsFV3kbnMBZOBQW85RQrgvV7OJmOciUf1n4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718868894; c=relaxed/simple; bh=utnGBcGfqhx3odsMMUpnDqRZ87HpmTagQZGorlaBLQY=; h=Message-ID:Subject:Date:From:To:Cc:References:In-Reply-To; b=KPOLQDxWjB4bCN7QCiOr+PYIlblrUOEGSTG1Z2A0B7LVu6AZ6rjfCl/j0DqAKuD0rJbY8CuUhzZpEbvhxbV6IvXDRB77t7p7dbGLlYZB9kAKinPub/Wuc1WrivbGO9aYfHcx5B7ATAo4ndY/1q0EegkfHXMLkvfgLBJ37FdJUMI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=yE9SssuR; arc=none smtp.client-ip=115.124.30.97 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="yE9SssuR" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1718868883; h=Message-ID:Subject:Date:From:To; bh=d9iPSVqNJ1QqmN6EFZNWgjHrK3uM1ZJvNdZTn7+Ymtw=; b=yE9SssuRtgEAeN+px+1Dbk5rrsaIUmISAqVPOwegBA1dy9WCWkyZa/2YlftRSaK3DSNKF1rpTgNR+ZCKAMnC0e2UjVzNs7PFAJ42Oxg7GYFrx3Xx1Rx6uy6iiZvNzeg83vowMBM3QTwiyO4+XBg2lA0goZGQlN1pIAbom3j871U= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033045046011;MF=hengqi@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0W8qVGgm_1718868882; Received: from localhost(mailfrom:hengqi@linux.alibaba.com fp:SMTPD_---0W8qVGgm_1718868882) by smtp.aliyun-inc.com; Thu, 20 Jun 2024 15:34:43 +0800 Message-ID: <1718868555.2701075-5-hengqi@linux.alibaba.com> Subject: Re: [PATCH net-next v4 2/5] virtio_net: enable irq for the control vq Date: Thu, 20 Jun 2024 15:29:15 +0800 From: Heng Qi To: "Michael S. Tsirkin" Cc: netdev@vger.kernel.org, virtualization@lists.linux.dev, Jason Wang , Xuan Zhuo , =?utf-8?q?Eugenio_P=C3=A9rez?= , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni References: <20240619161908.82348-1-hengqi@linux.alibaba.com> <20240619161908.82348-3-hengqi@linux.alibaba.com> <20240619171708-mutt-send-email-mst@kernel.org> In-Reply-To: <20240619171708-mutt-send-email-mst@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: On Wed, 19 Jun 2024 17:19:12 -0400, "Michael S. Tsirkin" wrote: > On Thu, Jun 20, 2024 at 12:19:05AM +0800, Heng Qi wrote: > > @@ -5312,7 +5315,7 @@ static int virtnet_find_vqs(struct virtnet_info *vi) > > > > /* Parameters for control virtqueue, if any */ > > if (vi->has_cvq) { > > - callbacks[total_vqs - 1] = NULL; > > + callbacks[total_vqs - 1] = virtnet_cvq_done; > > names[total_vqs - 1] = "control"; > > } > > > > If the # of MSIX vectors is exactly for data path VQs, > this will cause irq sharing between VQs which will degrade > performance significantly. > > So no, you can not just do it unconditionally. > > The correct fix probably requires virtio core/API extensions. If the introduction of cvq irq causes interrupts to become shared, then ctrlq need to fall back to polling mode and keep the status quo. Thanks. > > -- > MST >