| Message ID | 1521513753-7325-18-git-send-email-okaya@codeaurora.org |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | netdev: Eliminate duplicate barriers on weakly-ordered archs | expand |
I think you should either add a parameter to ena_com_write_sq_doorbell() or add ena_com_write_sq_doorbell_rel().
Right now, you have unused function.
On 3/20/18, 4:43 AM, "Sinan Kaya" <okaya@codeaurora.org> wrote:
Code includes barrier() followed by writel(). writel() already has a
barrier
on some architectures like arm64.
This ends up CPU observing two barriers back to back before executing the
register write.
Create a new wrapper function with relaxed write operator. Use the new
wrapper when a write is following a barrier().
Since code already has an explicit barrier call, changing writel() to
writel_relaxed().
Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
drivers/net/ethernet/amazon/ena/ena_com.c | 6 ++++--
drivers/net/ethernet/amazon/ena/ena_eth_com.h | 22 ++++++++++++++++++++--
drivers/net/ethernet/amazon/ena/ena_netdev.c | 4 ++--
3 files changed, 26 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c b/drivers/net/ethernet/amazon/ena/ena_com.c
index bf2de52..b6e628f 100644
--- a/drivers/net/ethernet/amazon/ena/ena_com.c
+++ b/drivers/net/ethernet/amazon/ena/ena_com.c
@@ -631,7 +631,8 @@ static u32 ena_com_reg_bar_read32(struct ena_com_dev *ena_dev, u16 offset)
*/
wmb();
- writel(mmio_read_reg, ena_dev->reg_bar + ENA_REGS_MMIO_REG_READ_OFF);
+ writel_relaxed(mmio_read_reg,
+ ena_dev->reg_bar + ENA_REGS_MMIO_REG_READ_OFF);
for (i = 0; i < timeout; i++) {
if (read_resp->req_id == mmio_read->seq_num)
@@ -1826,7 +1827,8 @@ void ena_com_aenq_intr_handler(struct ena_com_dev *dev, void *data)
/* write the aenq doorbell after all AENQ descriptors were read */
mb();
- writel((u32)aenq->head, dev->reg_bar + ENA_REGS_AENQ_HEAD_DB_OFF);
+ writel_relaxed((u32)aenq->head,
+ dev->reg_bar + ENA_REGS_AENQ_HEAD_DB_OFF);
}
int ena_com_dev_reset(struct ena_com_dev *ena_dev,
diff --git a/drivers/net/ethernet/amazon/ena/ena_eth_com.h b/drivers/net/ethernet/amazon/ena/ena_eth_com.h
index 2f76572..09ef7cd 100644
--- a/drivers/net/ethernet/amazon/ena/ena_eth_com.h
+++ b/drivers/net/ethernet/amazon/ena/ena_eth_com.h
@@ -107,7 +107,8 @@ static inline int ena_com_sq_empty_space(struct ena_com_io_sq *io_sq)
return io_sq->q_depth - 1 - cnt;
}
-static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq)
+static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq,
+ bool relaxed)
{
u16 tail;
@@ -116,7 +117,24 @@ static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq)
pr_debug("write submission queue doorbell for queue: %d tail: %d\n",
io_sq->qid, tail);
- writel(tail, io_sq->db_addr);
+ if (relaxed)
+ writel_relaxed(tail, io_sq->db_addr);
+ else
+ writel(tail, io_sq->db_addr);
+
+ return 0;
+}
+
+static inline int ena_com_write_sq_doorbell_rel(struct ena_com_io_sq *io_sq)
+{
+ u16 tail;
+
+ tail = io_sq->tail;
+
+ pr_debug("write submission queue doorbell for queue: %d tail: %d\n",
+ io_sq->qid, tail);
+
+ writel_relaxed(tail, io_sq->db_addr);
return 0;
}
diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
index 6975150..0530201 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -556,7 +556,7 @@ static int ena_refill_rx_bufs(struct ena_ring *rx_ring, u32 num)
* issue a doorbell
*/
wmb();
- ena_com_write_sq_doorbell(rx_ring->ena_com_io_sq);
+ ena_com_write_sq_doorbell(rx_ring->ena_com_io_sq, true);
}
rx_ring->next_to_use = next_to_use;
@@ -2151,7 +2151,7 @@ static netdev_tx_t ena_start_xmit(struct sk_buff *skb, struct net_device *dev)
if (netif_xmit_stopped(txq) || !skb->xmit_more) {
/* trigger the dma engine */
- ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq);
+ ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq, false);
u64_stats_update_begin(&tx_ring->syncp);
tx_ring->tx_stats.doorbells++;
u64_stats_update_end(&tx_ring->syncp);
--
2.7.4
On 2018-03-25 08:06, Belgazal, Netanel wrote: > I think you should either add a parameter to > ena_com_write_sq_doorbell() or add ena_com_write_sq_doorbell_rel(). > Right now, you have unused function. That is true. I got rid of ena_com_write_sq_doorbell_rel. > > On 3/20/18, 4:43 AM, "Sinan Kaya" <okaya@codeaurora.org> wrote: > > Code includes barrier() followed by writel(). writel() already has > a > barrier > on some architectures like arm64. > > This ends up CPU observing two barriers back to back before > executing the > register write. > > Create a new wrapper function with relaxed write operator. Use the > new > wrapper when a write is following a barrier(). > > Since code already has an explicit barrier call, changing writel() > to > writel_relaxed(). > > Signed-off-by: Sinan Kaya <okaya@codeaurora.org> > --- > drivers/net/ethernet/amazon/ena/ena_com.c | 6 ++++-- > drivers/net/ethernet/amazon/ena/ena_eth_com.h | 22 > ++++++++++++++++++++-- > drivers/net/ethernet/amazon/ena/ena_netdev.c | 4 ++-- > 3 files changed, 26 insertions(+), 6 deletions(-) > > diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c > b/drivers/net/ethernet/amazon/ena/ena_com.c > index bf2de52..b6e628f 100644 > --- a/drivers/net/ethernet/amazon/ena/ena_com.c > +++ b/drivers/net/ethernet/amazon/ena/ena_com.c > @@ -631,7 +631,8 @@ static u32 ena_com_reg_bar_read32(struct > ena_com_dev *ena_dev, u16 offset) > */ > wmb(); > > - writel(mmio_read_reg, ena_dev->reg_bar + > ENA_REGS_MMIO_REG_READ_OFF); > + writel_relaxed(mmio_read_reg, > + ena_dev->reg_bar + ENA_REGS_MMIO_REG_READ_OFF); > > for (i = 0; i < timeout; i++) { > if (read_resp->req_id == mmio_read->seq_num) > @@ -1826,7 +1827,8 @@ void ena_com_aenq_intr_handler(struct > ena_com_dev *dev, void *data) > > /* write the aenq doorbell after all AENQ descriptors were read > */ > mb(); > - writel((u32)aenq->head, dev->reg_bar + > ENA_REGS_AENQ_HEAD_DB_OFF); > + writel_relaxed((u32)aenq->head, > + dev->reg_bar + ENA_REGS_AENQ_HEAD_DB_OFF); > } > > int ena_com_dev_reset(struct ena_com_dev *ena_dev, > diff --git a/drivers/net/ethernet/amazon/ena/ena_eth_com.h > b/drivers/net/ethernet/amazon/ena/ena_eth_com.h > index 2f76572..09ef7cd 100644 > --- a/drivers/net/ethernet/amazon/ena/ena_eth_com.h > +++ b/drivers/net/ethernet/amazon/ena/ena_eth_com.h > @@ -107,7 +107,8 @@ static inline int > ena_com_sq_empty_space(struct ena_com_io_sq *io_sq) > return io_sq->q_depth - 1 - cnt; > } > > -static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq > *io_sq) > +static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq > *io_sq, > + bool relaxed) > { > u16 tail; > > @@ -116,7 +117,24 @@ static inline int > ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq) > pr_debug("write submission queue doorbell for queue: %d tail: > %d\n", > io_sq->qid, tail); > > - writel(tail, io_sq->db_addr); > + if (relaxed) > + writel_relaxed(tail, io_sq->db_addr); > + else > + writel(tail, io_sq->db_addr); > + > + return 0; > +} > + > +static inline int ena_com_write_sq_doorbell_rel(struct > ena_com_io_sq *io_sq) > +{ > + u16 tail; > + > + tail = io_sq->tail; > + > + pr_debug("write submission queue doorbell for queue: %d tail: > %d\n", > + io_sq->qid, tail); > + > + writel_relaxed(tail, io_sq->db_addr); > > return 0; > } > diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c > b/drivers/net/ethernet/amazon/ena/ena_netdev.c > index 6975150..0530201 100644 > --- a/drivers/net/ethernet/amazon/ena/ena_netdev.c > +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c > @@ -556,7 +556,7 @@ static int ena_refill_rx_bufs(struct ena_ring > *rx_ring, u32 num) > * issue a doorbell > */ > wmb(); > - ena_com_write_sq_doorbell(rx_ring->ena_com_io_sq); > + ena_com_write_sq_doorbell(rx_ring->ena_com_io_sq, true); > } > > rx_ring->next_to_use = next_to_use; > @@ -2151,7 +2151,7 @@ static netdev_tx_t ena_start_xmit(struct > sk_buff *skb, struct net_device *dev) > > if (netif_xmit_stopped(txq) || !skb->xmit_more) { > /* trigger the dma engine */ > - ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq); > + ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq, false); > u64_stats_update_begin(&tx_ring->syncp); > tx_ring->tx_stats.doorbells++; > u64_stats_update_end(&tx_ring->syncp); > -- > 2.7.4
diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c b/drivers/net/ethernet/amazon/ena/ena_com.c index bf2de52..b6e628f 100644 --- a/drivers/net/ethernet/amazon/ena/ena_com.c +++ b/drivers/net/ethernet/amazon/ena/ena_com.c @@ -631,7 +631,8 @@ static u32 ena_com_reg_bar_read32(struct ena_com_dev *ena_dev, u16 offset) */ wmb(); - writel(mmio_read_reg, ena_dev->reg_bar + ENA_REGS_MMIO_REG_READ_OFF); + writel_relaxed(mmio_read_reg, + ena_dev->reg_bar + ENA_REGS_MMIO_REG_READ_OFF); for (i = 0; i < timeout; i++) { if (read_resp->req_id == mmio_read->seq_num) @@ -1826,7 +1827,8 @@ void ena_com_aenq_intr_handler(struct ena_com_dev *dev, void *data) /* write the aenq doorbell after all AENQ descriptors were read */ mb(); - writel((u32)aenq->head, dev->reg_bar + ENA_REGS_AENQ_HEAD_DB_OFF); + writel_relaxed((u32)aenq->head, + dev->reg_bar + ENA_REGS_AENQ_HEAD_DB_OFF); } int ena_com_dev_reset(struct ena_com_dev *ena_dev, diff --git a/drivers/net/ethernet/amazon/ena/ena_eth_com.h b/drivers/net/ethernet/amazon/ena/ena_eth_com.h index 2f76572..09ef7cd 100644 --- a/drivers/net/ethernet/amazon/ena/ena_eth_com.h +++ b/drivers/net/ethernet/amazon/ena/ena_eth_com.h @@ -107,7 +107,8 @@ static inline int ena_com_sq_empty_space(struct ena_com_io_sq *io_sq) return io_sq->q_depth - 1 - cnt; } -static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq) +static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq, + bool relaxed) { u16 tail; @@ -116,7 +117,24 @@ static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq) pr_debug("write submission queue doorbell for queue: %d tail: %d\n", io_sq->qid, tail); - writel(tail, io_sq->db_addr); + if (relaxed) + writel_relaxed(tail, io_sq->db_addr); + else + writel(tail, io_sq->db_addr); + + return 0; +} + +static inline int ena_com_write_sq_doorbell_rel(struct ena_com_io_sq *io_sq) +{ + u16 tail; + + tail = io_sq->tail; + + pr_debug("write submission queue doorbell for queue: %d tail: %d\n", + io_sq->qid, tail); + + writel_relaxed(tail, io_sq->db_addr); return 0; } diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c index 6975150..0530201 100644 --- a/drivers/net/ethernet/amazon/ena/ena_netdev.c +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c @@ -556,7 +556,7 @@ static int ena_refill_rx_bufs(struct ena_ring *rx_ring, u32 num) * issue a doorbell */ wmb(); - ena_com_write_sq_doorbell(rx_ring->ena_com_io_sq); + ena_com_write_sq_doorbell(rx_ring->ena_com_io_sq, true); } rx_ring->next_to_use = next_to_use; @@ -2151,7 +2151,7 @@ static netdev_tx_t ena_start_xmit(struct sk_buff *skb, struct net_device *dev) if (netif_xmit_stopped(txq) || !skb->xmit_more) { /* trigger the dma engine */ - ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq); + ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq, false); u64_stats_update_begin(&tx_ring->syncp); tx_ring->tx_stats.doorbells++; u64_stats_update_end(&tx_ring->syncp);
Code includes barrier() followed by writel(). writel() already has a barrier on some architectures like arm64. This ends up CPU observing two barriers back to back before executing the register write. Create a new wrapper function with relaxed write operator. Use the new wrapper when a write is following a barrier(). Since code already has an explicit barrier call, changing writel() to writel_relaxed(). Signed-off-by: Sinan Kaya <okaya@codeaurora.org> --- drivers/net/ethernet/amazon/ena/ena_com.c | 6 ++++-- drivers/net/ethernet/amazon/ena/ena_eth_com.h | 22 ++++++++++++++++++++-- drivers/net/ethernet/amazon/ena/ena_netdev.c | 4 ++-- 3 files changed, 26 insertions(+), 6 deletions(-)