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Subject: Re: [PATCH v2] virtio_ring: use alloc_pages_node for NUMA-aware
 allocation
To:     "Michael S. Tsirkin" <mst@redhat.com>
Cc:     Jason Wang <jasowang@redhat.com>,
        virtualization@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org, kernel test robot <lkp@intel.com>,
        Jiang Liu <liuj97@gmail.com>, linux-pci@vger.kernel.org,
        bhelgaas@google.com
References: <20200721070013.62894-1-shile.zhang@linux.alibaba.com>
 <20200721041550-mutt-send-email-mst@kernel.org>
From:   Shile Zhang <shile.zhang@linux.alibaba.com>
Message-ID: <d16c8191-3837-8734-8cdf-ae6dd75725f7@linux.alibaba.com>
Date:   Tue, 21 Jul 2020 19:28:28 +0800
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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@intel.com>
>> Suggested-by: Jiang Liu <liuj97@gmail.com>
>> Signed-off-by: Shile Zhang <shile.zhang@linux.alibaba.com>
> 
> 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!

> 
> Bjorn, what do you think? Was this considered?
> 
>> ---
>> Changelog
>> v1 -> v2:
>> - fixed compile warning reported by LKP.
>> ---
>>   drivers/virtio/virtio_ring.c | 10 ++++++----
>>   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,
>>   		return dma_alloc_coherent(vdev->dev.parent, size,
>>   					  dma_handle, flag);
>>   	} else {
>> -		void *queue = alloc_pages_exact(PAGE_ALIGN(size), flag);
>> -
>> -		if (queue) {
>> +		void *queue = NULL;
>> +		struct page *page = alloc_pages_node(dev_to_node(vdev->dev.parent),
>> +						     flag, get_order(size));
>> +		if (page) {
>> +			queue = page_address(page);
>>   			phys_addr_t phys_addr = virt_to_phys(queue);
>>   			*dma_handle = (dma_addr_t)phys_addr;
>>   
>> @@ -308,7 +310,7 @@ static void vring_free_queue(struct virtio_device *vdev, size_t size,
>>   	if (vring_use_dma_api(vdev))
>>   		dma_free_coherent(vdev->dev.parent, size, queue, dma_handle);
>>   	else
>> -		free_pages_exact(queue, PAGE_ALIGN(size));
>> +		free_pages((unsigned long)queue, get_order(size));
>>   }
>>   
>>   /*
>> -- 
>> 2.24.0.rc2