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]) (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 967DD1773A for ; Tue, 9 Apr 2024 05:40:45 +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=1712641247; cv=none; b=VetFpi+J5hLl7GasY33r1oablZogIrS3HeqvIFliBr7eF06Pve2eIJv3V9/zR1etZ/9WUy8JAxZC6F6j6tvlPXPd6OQzODuh5TtYGHEkBilHdZwDQpMn6ZtmoLv+vMYKvcP7LQKDsQU54P+/W/GgHkaeZV7v8RD2zyi5nZo/BG0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712641247; c=relaxed/simple; bh=cKx/XEApGcdgkkBoYHguipdiISKD6oH161Z5fFjIQ/s=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: In-Reply-To:Content-Type:Content-Disposition; b=pQ9oCAqcIlNR4K3ipt4vnsl+Pk82FJR+gQCrFmyqbeRAVO1jrT1ifVSCJw1hJBFAX6jWpkVcldmm7T08ujHoxx8+wPArvHV1kq+uJ47RnrN5WUL8GJw6wWQg3dxvqgqsLnPYEFYqXqKZm4HZgE89c4GFGA7+UU5/qUpTnKJaNDo= 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=gw7orvO7; 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="gw7orvO7" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1712641244; 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: in-reply-to:in-reply-to:references:references; bh=vP+SQe4NJzDMBR5/uL7vUmv1IMo2/chbDROQYoC6bdg=; b=gw7orvO7iYgFjY77mnB4wSJnkoXIyHayRVfwc/K8hWdqG9yPo2jh1Cq0mxdA854tCT8VfE A+fsRzkcAl8WO/qR4X9D8wDcqTNSXXwvqPj9MXNVymANonpj+mRjSocSia+NOZkabTjMp0 OxoXB1mrpp+wddyvz2f+tdFnAsTW2G8= Received: from mail-lj1-f199.google.com (mail-lj1-f199.google.com [209.85.208.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-246-UuAqw9jqPmCDX7_gWgyKRw-1; Tue, 09 Apr 2024 01:40:42 -0400 X-MC-Unique: UuAqw9jqPmCDX7_gWgyKRw-1 Received: by mail-lj1-f199.google.com with SMTP id 38308e7fff4ca-2d6c94d98afso49095511fa.3 for ; Mon, 08 Apr 2024 22:40:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1712641241; x=1713246041; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=vP+SQe4NJzDMBR5/uL7vUmv1IMo2/chbDROQYoC6bdg=; b=oPt0zwQFvSB+8JlPyMqVILnPu/sedXyyrcz9sUZKQJVJRAJZkO1iAyps3psKK9B2qG M8qdlwEZFgRiFQHy7d2Tt3JZhf7/zOUN3BHx6CKEoAn1xoDYf6fHYY/RfhrL14BaORlO rcaMpY9BBfn7PodcfTmy2VeQuUMSj3ukE8pCkL+u4IQDPHna5t4lFJUjD/hyDrPDKDe1 LiTWjOl2m8nlwfvu/IxPKJ57b0v9pgRmfJcGTeGgSPwCcoUKNkD0tStchikmkco3nkfB txXnHad3mUdSlPk/EQqenl2ZSOFtSm0ikGIIf3dA0UdoUV/OsCRHzJLUzJbTz5LMqH7s /rNw== X-Forwarded-Encrypted: i=1; AJvYcCUwaKc6tPNnIl9fC49ZM3txk6pC+pbJDx/4pfMuSduz3UHK2+GxDDmXGkeDBys/rt30Cq/D0ll/mi3gh+nBNdWJ12LgdEu1SH6nBuudX2s= X-Gm-Message-State: AOJu0YycMNXyVKtB2JoUNgfNXhHPNgAjA4w+ZErGidJ3Mt8VK8KFSt+Q vLf0fJMG+xpYXh55KSzyDmXgETJYNFLQc7CGJhbOe2tq7Ig0x9FQWS5ETjTg8GkcajcO5d/40tj Ab+Oe79TbRWtbSpR58sNgZaehuuqppN+qPr1YAn598At2WTHvAjujiYM/sp9Q/u2dupaJOvYt X-Received: by 2002:a2e:9f0c:0:b0:2d4:3d86:54e2 with SMTP id u12-20020a2e9f0c000000b002d43d8654e2mr6914069ljk.27.1712641240917; Mon, 08 Apr 2024 22:40:40 -0700 (PDT) X-Google-Smtp-Source: AGHT+IH+qn0i6whv8AwTjlwkCerpWrTLCi6WhpXkJ62FFmQBBsOuWv8O1bHDdwijM/xD7mQUbvhuFA== X-Received: by 2002:a2e:9f0c:0:b0:2d4:3d86:54e2 with SMTP id u12-20020a2e9f0c000000b002d43d8654e2mr6914058ljk.27.1712641240359; Mon, 08 Apr 2024 22:40:40 -0700 (PDT) Received: from redhat.com ([2.52.134.26]) by smtp.gmail.com with ESMTPSA id z15-20020a5d4c8f000000b00343daeddcb2sm10614463wrs.45.2024.04.08.22.40.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Apr 2024 22:40:39 -0700 (PDT) Date: Tue, 9 Apr 2024 01:40:36 -0400 From: "Michael S. Tsirkin" To: lyx634449800 Cc: jasowang@redhat.com, angus.chen@jaguarmicro.com, virtualization@lists.linux.dev, xuanzhuo@linux.alibaba.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] vp_vdpa: fix the method of calculating vectors Message-ID: <20240409013020-mutt-send-email-mst@kernel.org> References: <20240408035346-mutt-send-email-mst@kernel.org> <20240409014935.944-1-yuxue.liu@jaguarmicro.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20240409014935.944-1-yuxue.liu@jaguarmicro.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline better subject: vp_vdpa: don't allocate unused msix vectors to make it clear it's not a bugfix. more comments below, but most importantly this looks like it adds a bug. On Tue, Apr 09, 2024 at 09:49:35AM +0800, lyx634449800 wrote: > When there is a ctlq and it doesn't require interrupt > callbacks,the original method of calculating vectors > wastes hardware msi or msix resources as well as system > IRQ resources. > > When conducting performance testing using testpmd in the > guest os, it was found that the performance was lower compared > to directly using vfio-pci to passthrough the device > > In scenarios where the virtio device in the guest os does > not utilize interrupts, the vdpa driver still configures > the hardware's msix vector. Therefore, the hardware still > sends interrupts to the host os. Because of this unnecessary > action by the hardware, hardware performance decreases, and > it also affects the performance of the host os. > > Before modification:(interrupt mode) > 32: 0 0 0 0 PCI-MSI 32768-edge vp-vdpa[0000:00:02.0]-0 > 33: 0 0 0 0 PCI-MSI 32769-edge vp-vdpa[0000:00:02.0]-1 > 34: 0 0 0 0 PCI-MSI 32770-edge vp-vdpa[0000:00:02.0]-2 > 35: 0 0 0 0 PCI-MSI 32771-edge vp-vdpa[0000:00:02.0]-config > > After modification:(interrupt mode) > 32: 0 0 1 7 PCI-MSI 32768-edge vp-vdpa[0000:00:02.0]-0 > 33: 36 0 3 0 PCI-MSI 32769-edge vp-vdpa[0000:00:02.0]-1 > 34: 0 0 0 0 PCI-MSI 32770-edge vp-vdpa[0000:00:02.0]-config > > Before modification:(virtio pmd mode for guest os) > 32: 0 0 0 0 PCI-MSI 32768-edge vp-vdpa[0000:00:02.0]-0 > 33: 0 0 0 0 PCI-MSI 32769-edge vp-vdpa[0000:00:02.0]-1 > 34: 0 0 0 0 PCI-MSI 32770-edge vp-vdpa[0000:00:02.0]-2 > 35: 0 0 0 0 PCI-MSI 32771-edge vp-vdpa[0000:00:02.0]-config > > After modification:(virtio pmd mode for guest os) > 32: 0 0 0 0 PCI-MSI 32768-edge vp-vdpa[0000:00:02.0]-config > > To verify the use of the virtio PMD mode in the guest operating > system, the following patch needs to be applied to QEMU: > https://lore.kernel.org/all/20240408073311.2049-1-yuxue.liu@jaguarmicro.com > > Signed-off-by: lyx634449800 Bad S.O.B format. Should be Signed-off-by: Real Name > --- > > V3: delete unused variables and add validation records > V2: fix when allocating IRQs, scan all queues > > drivers/vdpa/virtio_pci/vp_vdpa.c | 35 +++++++++++++++++++------------ > 1 file changed, 22 insertions(+), 13 deletions(-) > > diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c b/drivers/vdpa/virtio_pci/vp_vdpa.c > index df5f4a3bccb5..cd3aeb3b8f21 100644 > --- a/drivers/vdpa/virtio_pci/vp_vdpa.c > +++ b/drivers/vdpa/virtio_pci/vp_vdpa.c > @@ -160,22 +160,31 @@ static int vp_vdpa_request_irq(struct vp_vdpa *vp_vdpa) > struct pci_dev *pdev = mdev->pci_dev; > int i, ret, irq; > int queues = vp_vdpa->queues; > - int vectors = queues + 1; > + int msix_vec, allocated_vectors = 0; I would actually call allocated_vectors -> vectors, make the patch smaller. > > - ret = pci_alloc_irq_vectors(pdev, vectors, vectors, PCI_IRQ_MSIX); > - if (ret != vectors) { > + for (i = 0; i < queues; i++) { > + if (vp_vdpa->vring[i].cb.callback) > + allocated_vectors++; > + } > + allocated_vectors = allocated_vectors + 1; better: allocated_vectors++; /* extra one for config */ > + > + ret = pci_alloc_irq_vectors(pdev, allocated_vectors, allocated_vectors, > + PCI_IRQ_MSIX); > + if (ret != allocated_vectors) { > dev_err(&pdev->dev, > "vp_vdpa: fail to allocate irq vectors want %d but %d\n", > - vectors, ret); > + allocated_vectors, ret); > return ret; > } > - > - vp_vdpa->vectors = vectors; > + vp_vdpa->vectors = allocated_vectors; > > for (i = 0; i < queues; i++) { > + if (!vp_vdpa->vring[i].cb.callback) > + continue; > + > snprintf(vp_vdpa->vring[i].msix_name, VP_VDPA_NAME_SIZE, > "vp-vdpa[%s]-%d\n", pci_name(pdev), i); > - irq = pci_irq_vector(pdev, i); > + irq = pci_irq_vector(pdev, msix_vec); using uninitialized msix_vec here? I would expect compiler to warn about it. pay attention to compiler warnings pls. > ret = devm_request_irq(&pdev->dev, irq, > vp_vdpa_vq_handler, > 0, vp_vdpa->vring[i].msix_name, > @@ -185,23 +194,23 @@ static int vp_vdpa_request_irq(struct vp_vdpa *vp_vdpa) > "vp_vdpa: fail to request irq for vq %d\n", i); > goto err; > } > - vp_modern_queue_vector(mdev, i, i); > + vp_modern_queue_vector(mdev, i, msix_vec); > vp_vdpa->vring[i].irq = irq; > + msix_vec++; > } > > snprintf(vp_vdpa->msix_name, VP_VDPA_NAME_SIZE, "vp-vdpa[%s]-config\n", > - pci_name(pdev)); > - irq = pci_irq_vector(pdev, queues); > + pci_name(pdev)); don't move pci_name - don't make unrelated code changes. > + irq = pci_irq_vector(pdev, msix_vec); > ret = devm_request_irq(&pdev->dev, irq, vp_vdpa_config_handler, 0, > vp_vdpa->msix_name, vp_vdpa); > if (ret) { > dev_err(&pdev->dev, > - "vp_vdpa: fail to request irq for vq %d\n", i); > + "vp_vdpa: fail to request irq for config\n"); I would report ret here too. > goto err; > } > - vp_modern_config_vector(mdev, queues); > + vp_modern_config_vector(mdev, msix_vec); > vp_vdpa->config_irq = irq; > - don't make unrelated code changes. > return 0; > err: > vp_vdpa_free_irq(vp_vdpa); > -- > 2.43.0