Re: [PATCH v5] vp_vdpa: don't allocate unused msix vectors
> > > > to the host os. > > > > > > >I just have a question on this part. How come hardware sends > > > >interrupts does > > not guest driver disable them? > > > > > >1：Assuming the guest OS's Virtio device is using PMD mode, QEMU > > > sets > > the call fd to -1 > > >2：On the host side, the vhost_vdpa program will set > > vp_vdpa->vring[i].cb.callback to invalid > > >3：Before the modification, the vp_vdpa_request_irq function > > > does not > > check whether > > > vp_vdpa->vring[i].cb.callback is valid. Instead, it enables > > > the > > hardware's MSIX > > > interrupts based on the number of queues of the device > > > > > > > So MSIX is enabled but why would it trigger? virtio PMD in poll mode > > presumably suppresses interrupts after all. > Virtio pmd is in the guest,but in host side,the msix is enabled,then > the device will triger Interrupt normally. I analysed this bug before,and I > think gavin is right. > Did I make it clear? Not really. Guest disables interrupts presumably (it's polling) why does device still send them? > > > > > > > > > > > - Original Message - > > > From: Michael S. Tsirkin m...@redhat.com > > > Sent: April 22, 2024 20:09 > > > To: Gavin Liu gavin@jaguarmicro.com > > > Cc: jasow...@redhat.com; Angus Chen angus.c...@jaguarmicro.com; > > virtualizat...@lists.linux.dev; xuanz...@linux.alibaba.com; > > linux-kernel@vger.kernel.org; Heng Qi hen...@linux.alibaba.com > > > Subject: Re: [PATCH v5] vp_vdpa: don't allocate unused msix > > > vectors > > > > > > > > > > > > External Mail: This email originated from OUTSIDE of the organization! > > > Do not click links, open attachments or provide ANY information > > > unless you > > recognize the sender and know the content is safe. > > > > > > > > > On Wed, Apr 10, 2024 at 11:30:20AM +0800, lyx634449800 wrote: > > > > From: Yuxue Liu > > > > > > > > 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. > > > > > > I just have a question on this part. How come hardware sends > > > interrupts does > > not guest driver disable them? > > > > > > > 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-edgevp-vdpa[:00:02.0]-0 > > > > 33: 0 0 0 0 PCI-MSI 32769-edgevp-vdpa[:00:02.0]-1 > > > > 34: 0 0 0 0 PCI-MSI 32770-edgevp-vdpa[:00:02.0]-2 > > > > 35: 0 0 0 0 PCI-MSI 32771-edgevp-vdpa[:00:02.0]-config > > > > > > > > After modification:(interrupt mode) > > > > 32: 0 0 1 7 PCI-MSI 32768-edge vp-vdpa[:00:02.0]-0 > > > > 33: 36 0 3 0 PCI-MSI 32769-edge vp-vdpa[:00:02.0]-1 > > > > 34: 0 0 0 0 PCI-MSI 32770-edge vp-vdpa[:00:02.0]-config > > > > > > > > Before modification:(virtio pmd mode for guest os) > > > > 32: 0 0 0 0 PCI-MSI 32768-edgevp-vdpa[:00:02.0]-0 > > > > 33: 0 0 0 0 PCI-MSI 32769-edgevp-vdpa[:00:02.0]-1 > > > > 34: 0 0 0 0 PCI-MSI 32770-edgevp-vdpa[:00:02.0]-2 > > > > 35: 0 0 0 0 PCI-MSI 32771-edgevp-vdpa[:00:02.0]-config > > > > > > > > After modification:(virtio pmd mode for guest os) > > > > 32: 0 0 0 0 PCI-MSI 32768-edge vp-vdpa[:00:02.0]-config > > > > > > > > To verify the use of the virtio PMD mode in the guest operating > > > > system, the following patch needs to be
Re: [PATCH v5] vp_vdpa: don't allocate unused msix vectors
On Wed, Apr 10, 2024 at 11:30:20AM +0800, lyx634449800 wrote:
> From: Yuxue Liu
>
> 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.
I just have a question on this part. How come hardware
sends interrupts does not guest driver disable them?
> 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-edgevp-vdpa[:00:02.0]-0
> 33: 0 0 0 0 PCI-MSI 32769-edgevp-vdpa[:00:02.0]-1
> 34: 0 0 0 0 PCI-MSI 32770-edgevp-vdpa[:00:02.0]-2
> 35: 0 0 0 0 PCI-MSI 32771-edgevp-vdpa[:00:02.0]-config
>
> After modification:(interrupt mode)
> 32: 0 0 1 7 PCI-MSI 32768-edge vp-vdpa[:00:02.0]-0
> 33: 36 0 3 0 PCI-MSI 32769-edge vp-vdpa[:00:02.0]-1
> 34: 0 0 0 0 PCI-MSI 32770-edge vp-vdpa[:00:02.0]-config
>
> Before modification:(virtio pmd mode for guest os)
> 32: 0 0 0 0 PCI-MSI 32768-edgevp-vdpa[:00:02.0]-0
> 33: 0 0 0 0 PCI-MSI 32769-edgevp-vdpa[:00:02.0]-1
> 34: 0 0 0 0 PCI-MSI 32770-edgevp-vdpa[:00:02.0]-2
> 35: 0 0 0 0 PCI-MSI 32771-edgevp-vdpa[:00:02.0]-config
>
> After modification:(virtio pmd mode for guest os)
> 32: 0 0 0 0 PCI-MSI 32768-edge vp-vdpa[: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@jaguarmicro.com
>
> Signed-off-by: Yuxue Liu
> Acked-by: Jason Wang
> Reviewed-by: Heng Qi
> ---
> V5: modify the description of the printout when an exception occurs
> V4: update the title and assign values to uninitialized variables
> V3: delete unused variables and add validation records
> V2: fix when allocating IRQs, scan all queues
>
> drivers/vdpa/virtio_pci/vp_vdpa.c | 22 --
> 1 file changed, 16 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c
> b/drivers/vdpa/virtio_pci/vp_vdpa.c
> index df5f4a3bccb5..8de0224e9ec2 100644
> --- a/drivers/vdpa/virtio_pci/vp_vdpa.c
> +++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
> @@ -160,7 +160,13 @@ 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 vectors = 1;
> + int msix_vec = 0;
> +
> + for (i = 0; i < queues; i++) {
> + if (vp_vdpa->vring[i].cb.callback)
> + vectors++;
> + }
>
> ret = pci_alloc_irq_vectors(pdev, vectors, vectors, PCI_IRQ_MSIX);
> if (ret != vectors) {
> @@ -173,9 +179,12 @@ static int vp_vdpa_request_irq(struct vp_vdpa *vp_vdpa)
> vp_vdpa->vectors = 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);
> ret = devm_request_irq(>dev, irq,
> vp_vdpa_vq_handler,
> 0, vp_vdpa->vring[i].msix_name,
> @@ -185,21 +194,22 @@ 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);
> + irq = pci_irq_vector(pdev, msix_vec);
> ret = devm_request_irq(>dev, irq, vp_vdpa_config_handler, 0,
> vp_vdpa->msix_name, vp_vdpa);
> if (ret) {
> dev_err(>dev,
> - "vp_vdpa: fail to request irq for vq %d\n", i);
> + "vp_vdpa: fail to request irq for config: %d\n", ret);
> goto err;
> }
> -
Re: [PATCH v5] vp_vdpa: don't allocate unused msix vectors
Dear Michael,
I hope this email finds you well. I am reaching out to request your
assistance in reviewing a patch.
The patch in question is titled "[PATCH v5] vp_vdpa: don't allocate
unused msix vectors". I believe your expertise and insights would be invaluable
in ensuring the quality and effectiveness of this patch.
Your feedback and review are highly appreciated. Please let me know if
you have any questions or require further information.
Thank you for your time and consideration.
Best regards,
Yuxue Liu
-Original Message-
From: Gavin Liu
Sent: April 10, 2024 11:31
To: m...@redhat.com; jasow...@redhat.com
Cc: Angus Chen angus.c...@jaguarmicro.com; virtualizat...@lists.linux.dev;
xuanz...@linux.alibaba.com; Gavin Liu gavin@jaguarmicro.com;
linux-kernel@vger.kernel.org; Heng Qi hen...@linux.alibaba.com
Subject: [PATCH v5] vp_vdpa: don't allocate unused msix vectors
From: Yuxue Liu
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-edgevp-vdpa[:00:02.0]-0
33: 0 0 0 0 PCI-MSI 32769-edgevp-vdpa[:00:02.0]-1
34: 0 0 0 0 PCI-MSI 32770-edgevp-vdpa[:00:02.0]-2
35: 0 0 0 0 PCI-MSI 32771-edgevp-vdpa[:00:02.0]-config
After modification:(interrupt mode)
32: 0 0 1 7 PCI-MSI 32768-edge vp-vdpa[:00:02.0]-0
33: 36 0 3 0 PCI-MSI 32769-edge vp-vdpa[:00:02.0]-1
34: 0 0 0 0 PCI-MSI 32770-edge vp-vdpa[:00:02.0]-config
Before modification:(virtio pmd mode for guest os)
32: 0 0 0 0 PCI-MSI 32768-edgevp-vdpa[:00:02.0]-0
33: 0 0 0 0 PCI-MSI 32769-edgevp-vdpa[:00:02.0]-1
34: 0 0 0 0 PCI-MSI 32770-edgevp-vdpa[:00:02.0]-2
35: 0 0 0 0 PCI-MSI 32771-edgevp-vdpa[:00:02.0]-config
After modification:(virtio pmd mode for guest os)
32: 0 0 0 0 PCI-MSI 32768-edge vp-vdpa[: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@jaguarmicro.com
Signed-off-by: Yuxue Liu
Acked-by: Jason Wang
Reviewed-by: Heng Qi
---
V5: modify the description of the printout when an exception occurs
V4: update the title and assign values to uninitialized variables
V3: delete unused variables and add validation records
V2: fix when allocating IRQs, scan all queues
drivers/vdpa/virtio_pci/vp_vdpa.c | 22 --
1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c
b/drivers/vdpa/virtio_pci/vp_vdpa.c
index df5f4a3bccb5..8de0224e9ec2 100644
--- a/drivers/vdpa/virtio_pci/vp_vdpa.c
+++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
@@ -160,7 +160,13 @@ 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 vectors = 1;
+ int msix_vec = 0;
+
+ for (i = 0; i < queues; i++) {
+ if (vp_vdpa->vring[i].cb.callback)
+ vectors++;
+ }
ret = pci_alloc_irq_vectors(pdev, vectors, vectors, PCI_IRQ_MSIX);
if (ret != vectors) {
@@ -173,9 +179,12 @@ static int vp_vdpa_request_irq(struct vp_vdpa *vp_vdpa)
vp_vdpa->vectors = 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);
ret = devm_request_irq(>dev, irq,
vp_vdpa_vq_handler,
0, vp_vdpa->vring[i].msix_name, @@
-185,21 +194,22 @@ 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;
+
