答复: [外部邮件] Re: [PATCH][rdma-next] RDMA/erdma: Use NUMA-aware allocation for MTT tables

["Li,Rongqing(ACG CCN)" <lirongqing@baidu.com>]

> On 2/25/26 4:51 PM, lirongqing wrote:
> > From: Li RongQing <lirongqing@baidu.com>
> >
> > Currently, MTT (Memory Translation Table) buffers are allocated
> > without NUMA awareness using kzalloc() and vzalloc(), which allocate
> > memory on the NUMA node of the calling CPU. This can lead to
> > cross-node memory access latencies if the erdma device is attached to
> > a different NUMA socket.
> >
> > Switch to kzalloc_node() and vzalloc_node() to ensure MTT buffers are
> > allocated on the local NUMA node of the PCIe device (dev->attrs.numa_node).
> > This reduces latency for hardware access and improves performance.
> >
> > Signed-off-by: Li RongQing <lirongqing@baidu.com>
> > ---
> >  drivers/infiniband/hw/erdma/erdma_verbs.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> 
> Hi, Li RongQing,
> 
> Thanks for the patch. However, I think it is better to keep the current behavior,
> for the following reasons:
> 
> 1. This path is in the control plane, so allocating memory from a remote
>    NUMA node should not have a noticeable performance impact.

If TLB Miss , or the internal cache misses , does the HCA need to query the MTT?

[Li,Rongqing] 

> 2. With this change, the driver may fail the allocation when the local NUMA
>    node is out of memory, even if other nodes still have available memory.
> 
> Thanks,
> Cheng Xu
> 
> > diff --git a/drivers/infiniband/hw/erdma/erdma_verbs.c
> > b/drivers/infiniband/hw/erdma/erdma_verbs.c
> > index 9f74aad..58da6ef 100644
> > --- a/drivers/infiniband/hw/erdma/erdma_verbs.c
> > +++ b/drivers/infiniband/hw/erdma/erdma_verbs.c
> > @@ -604,7 +604,7 @@ static struct erdma_mtt
> *erdma_create_cont_mtt(struct erdma_dev *dev,
> >  		return ERR_PTR(-ENOMEM);
> >
> >  	mtt->size = size;
> > -	mtt->buf = kzalloc(mtt->size, GFP_KERNEL);
> > +	mtt->buf = kzalloc_node(mtt->size, GFP_KERNEL,
> > +dev->attrs.numa_node);
> >  	if (!mtt->buf)
> >  		goto err_free_mtt;
> >
> > @@ -729,7 +729,7 @@ static struct erdma_mtt
> *erdma_create_scatter_mtt(struct erdma_dev *dev,
> >  		return ERR_PTR(-ENOMEM);
> >
> >  	mtt->size = ALIGN(size, PAGE_SIZE);
> > -	mtt->buf = vzalloc(mtt->size);
> > +	mtt->buf = vzalloc_node(mtt->size, dev->attrs.numa_node);
> >  	mtt->continuous = false;
> >  	if (!mtt->buf)
> >  		goto err_free_mtt;