From: Sinan Kaya <okaya@codeaurora•org>
To: netdev@vger•kernel.org, timur@codeaurora•org, sulrich@codeaurora•org
Cc: linux-arm-msm@vger•kernel.org,
linux-arm-kernel@lists•infradead.org,
Sinan Kaya <okaya@codeaurora•org>,
Netanel Belgazal <netanel@amazon•com>,
Saeed Bishara <saeedb@amazon•com>,
Zorik Machulsky <zorik@amazon•com>,
"David S. Miller" <davem@davemloft•net>,
Tobias Klauser <tklauser@distanz•ch>,
linux-kernel@vger•kernel.org
Subject: [PATCH v4 17/17] net: ena: Eliminate duplicate barriers on weakly-ordered archs
Date: Mon, 19 Mar 2018 22:42:32 -0400 [thread overview]
Message-ID: <1521513753-7325-18-git-send-email-okaya@codeaurora.org> (raw)
In-Reply-To: <1521513753-7325-1-git-send-email-okaya@codeaurora.org>
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
next prev parent reply other threads:[~2018-03-20 2:42 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-20 2:42 [PATCH v4 00/17] netdev: Eliminate duplicate barriers on weakly-ordered archs Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 01/17] i40e/i40evf: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 02/17] ixgbe: eliminate " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 03/17] igbvf: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 04/17] igb: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 05/17] ixgbevf: keep writel() closer to wmb() Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 06/17] ixgbevf: eliminate duplicate barriers on weakly-ordered archs Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 07/17] fm10k: Eliminate " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 08/17] drivers: net: cxgb: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 09/17] net: qla3xxx: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 10/17] qlcnic: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 11/17] bnx2x: " Sinan Kaya
2018-03-22 10:10 ` Kalluru, Sudarsana
2018-03-20 2:42 ` [PATCH v4 12/17] net: cxgb4/cxgb4vf: " Sinan Kaya
2018-03-21 23:03 ` Casey Leedom
2018-03-22 0:00 ` okaya
2018-03-20 2:42 ` [PATCH v4 13/17] net: cxgb3: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 14/17] net: qlge: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 15/17] bnxt_en: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 16/17] qed/qede: " Sinan Kaya
2018-03-20 2:42 ` Sinan Kaya [this message]
2018-03-25 12:06 ` [PATCH v4 17/17] net: ena: " Belgazal, Netanel
2018-03-25 13:33 ` okaya
2018-03-21 15:56 ` [PATCH v4 00/17] netdev: " David Miller
2018-03-21 19:06 ` Sinan Kaya
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1521513753-7325-18-git-send-email-okaya@codeaurora.org \
--to=okaya@codeaurora$(echo .)org \
--cc=davem@davemloft$(echo .)net \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
--cc=linux-arm-msm@vger$(echo .)kernel.org \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=netanel@amazon$(echo .)com \
--cc=netdev@vger$(echo .)kernel.org \
--cc=saeedb@amazon$(echo .)com \
--cc=sulrich@codeaurora$(echo .)org \
--cc=timur@codeaurora$(echo .)org \
--cc=tklauser@distanz$(echo .)ch \
--cc=zorik@amazon$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox