Re: [PATCH v2] virtio_ring: use alloc_pages_node for NUMA-aware allocation

[Shile Zhang]

On 2020/7/21 19:28, Shile Zhang wrote:
> On 2020/7/21 16:18, Michael S. Tsirkin wrote:
> > On Tue, Jul 21, 2020 at 03:00:13PM +0800, Shile Zhang wrote:
> > > Use alloc_pages_node() allocate memory for vring queue with proper
> > > NUMA affinity.
> > >
> > > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > > Suggested-by: Jiang Liu <liuj97@xxxxxxxxx>
> > > Signed-off-by: Shile Zhang <shile.zhang@xxxxxxxxxxxxxxxxx>
> >
> > Do you observe any performance gains from this patch?
>
> Thanks for your comments!
> Yes, the bandwidth can boost more than doubled (from 30Gbps to 80GBps) 
> with this changes in my test env (8 numa nodes), with netperf test.
>
> > I also wonder why isn't the probe code run on the correct numa node?
> > That would fix a wide class of issues like this without need to tweak
> > drivers.
>
> Good point, I'll check this, thanks!

Sorry, I have no idea about how the probe code to grab the appropriate 
NUMA node.

> > Bjorn, what do you think? Was this considered?

Hi Bjorn, Could you please give any comments about this issue?
Thanks!

> > > ---
> > > Changelog
> > > v1 -> v2:
> > > - fixed compile warning reported by LKP.
> > > ---
> > > Â drivers/virtio/virtio_ring.c | 10 ++++++----
> > > Â 1 file changed, 6 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > > index 58b96baa8d48..d38fd6872c8c 100644
> > > --- a/drivers/virtio/virtio_ring.c
> > > +++ b/drivers/virtio/virtio_ring.c
> > > @@ -276,9 +276,11 @@ static void *vring_alloc_queue(struct 
> > > virtio_device *vdev, size_t size,
> > > ÂÂÂÂÂÂÂÂÂ return dma_alloc_coherent(vdev->dev.parent, size,
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ dma_handle, flag);
> > > ÂÂÂÂÂ } else {
> > > -ÂÂÂÂÂÂÂ void *queue = alloc_pages_exact(PAGE_ALIGN(size), flag);
> > > -
> > > -ÂÂÂÂÂÂÂ if (queue) {
> > > +ÂÂÂÂÂÂÂ void *queue = NULL;
> > > +ÂÂÂÂÂÂÂ struct page *page = 
> > > alloc_pages_node(dev_to_node(vdev->dev.parent),
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ flag, get_order(size));
> > > +ÂÂÂÂÂÂÂ if (page) {
> > > +ÂÂÂÂÂÂÂÂÂÂÂ queue = page_address(page);
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂ phys_addr_t phys_addr = virt_to_phys(queue);
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂ *dma_handle = (dma_addr_t)phys_addr;
> > > @@ -308,7 +310,7 @@ static void vring_free_queue(struct virtio_device 
> > > *vdev, size_t size,
> > > ÂÂÂÂÂ if (vring_use_dma_api(vdev))
> > > ÂÂÂÂÂÂÂÂÂ dma_free_coherent(vdev->dev.parent, size, queue, dma_handle);
> > > ÂÂÂÂÂ else
> > > -ÂÂÂÂÂÂÂ free_pages_exact(queue, PAGE_ALIGN(size));
> > > +ÂÂÂÂÂÂÂ free_pages((unsigned long)queue, get_order(size));
> > > Â }
> > > Â /*
> > > --
> > > 2.24.0.rc2