| Message ID | 20191022141438.22002-1-mcroce@redhat.com |
|---|---|
| State | Changes Requested |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net-next] mvpp2: prefetch frame header | expand |
From: Matteo Croce <mcroce@redhat.com> Date: Tue, 22 Oct 2019 16:14:38 +0200 > When receiving traffic, eth_type_trans() is high up on the perf top list, > because it's the first function which access the packet data. > > Move the DMA unmap a bit higher, and put a prefetch just after it, so we > have more time to load the data into the cache. > > The packet rate increase is about 13% with a tc drop test: 1620 => 1830 kpps > > Signed-off-by: Matteo Croce <mcroce@redhat.com> > --- > drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c > index 111b3b8239e1..17378e0d8da1 100644 > --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c > +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c > @@ -2966,6 +2966,11 @@ static int mvpp2_rx(struct mvpp2_port *port, struct napi_struct *napi, > continue; > } > > + dma_unmap_single(dev->dev.parent, dma_addr, > + bm_pool->buf_size, DMA_FROM_DEVICE); > + > + prefetch(data); > + > if (bm_pool->frag_size > PAGE_SIZE) > frag_size = 0; > else You cannot unmap it this early, because of all of the err_drop_frame code paths that might be taken next. The DMA mapping must stay in place in those cases.
On Thu, Oct 24, 2019 at 5:28 AM David Miller <davem@davemloft.net> wrote: > You cannot unmap it this early, because of all of the err_drop_frame > code paths that might be taken next. The DMA mapping must stay in place > in those cases. Thanks for noting this. I'm sending a series with this and other small fixes. Regards,
diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c index 111b3b8239e1..17378e0d8da1 100644 --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c @@ -2966,6 +2966,11 @@ static int mvpp2_rx(struct mvpp2_port *port, struct napi_struct *napi, continue; } + dma_unmap_single(dev->dev.parent, dma_addr, + bm_pool->buf_size, DMA_FROM_DEVICE); + + prefetch(data); + if (bm_pool->frag_size > PAGE_SIZE) frag_size = 0; else @@ -2983,9 +2988,6 @@ static int mvpp2_rx(struct mvpp2_port *port, struct napi_struct *napi, goto err_drop_frame; } - dma_unmap_single(dev->dev.parent, dma_addr, - bm_pool->buf_size, DMA_FROM_DEVICE); - rcvd_pkts++; rcvd_bytes += rx_bytes;
When receiving traffic, eth_type_trans() is high up on the perf top list, because it's the first function which access the packet data. Move the DMA unmap a bit higher, and put a prefetch just after it, so we have more time to load the data into the cache. The packet rate increase is about 13% with a tc drop test: 1620 => 1830 kpps Signed-off-by: Matteo Croce <mcroce@redhat.com> --- drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)