From: Sinan Kaya <okaya@codeaurora.org>
To: linux-rdma@vger.kernel.org, timur@codeaurora.org, sulrich@codeaurora.org
Cc: linux-arm-msm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Michal Kalderon <Michal.Kalderon@cavium.com>,
Ariel Elior <Ariel.Elior@cavium.com>,
Doug Ledford <dledford@redhat.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 3/3] RDMA/qedr: eliminate duplicate barriers on weakly-ordered archs #2
Date: Mon, 2 Apr 2018 22:29:53 -0400 [thread overview]
Message-ID: <ac46b4e4-7e6c-c15f-06eb-01b1e4893d50@codeaurora.org> (raw)
In-Reply-To: <1521736009-23387-4-git-send-email-okaya@codeaurora.org>
On 3/22/2018 12:26 PM, Sinan Kaya wrote:
> @@ -860,7 +860,7 @@ static void doorbell_cq(struct qedr_cq *cq, u32 cons, u8 flags)
> wmb();
> cq->db.data.agg_flags = flags;
> cq->db.data.value = cpu_to_le32(cons);
> - writeq(cq->db.raw, cq->db_addr);
> + writeq_relaxed(cq->db.raw, cq->db_addr);
Given the direction to get rid of wmb() in front of writeX() functions, I have been
reviewing this code. Under normal circumstances, I can get rid of all wmb() as follows.
However, I started having my doubts now. Are these wmb() used as a SMP barrier too?
I can't find any smp_Xmb() in drivers/infiniband/hw/qedr directory.
static void doorbell_cq(struct qedr_cq *cq, u32 cons, u8 flags)
{
- /* Flush data before signalling doorbell */
- wmb();
cq->db.data.agg_flags = flags;
cq->db.data.value = cpu_to_le32(cons);
writeq(cq->db.raw, cq->db_addr);
@@ -1870,8 +1868,7 @@ static int qedr_update_qp_state(struct qedr_dev *dev,
*/
if (rdma_protocol_roce(&dev->ibdev, 1)) {
- wmb();
- writel_relaxed(qp->rq.db_data.raw, qp->rq.db);
+ writel(qp->rq.db_data.raw, qp->rq.db);
/* Make sure write takes effect */
mmiowb();
}
@@ -3275,8 +3272,7 @@ int qedr_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
* unchanged). For performance reasons we avoid checking for this
* redundant doorbell.
*/
- wmb();
- writel_relaxed(qp->sq.db_data.raw, qp->sq.db);
+ writel(qp->sq.db_data.raw, qp->sq.db);
/* Make sure write sticks */
mmiowb();
@@ -3362,9 +3358,6 @@ int qedr_post_recv(struct ib_qp *ibqp, struct ib_recv_wr *wr,
qedr_inc_sw_prod(&qp->rq);
- /* Flush all the writes before signalling doorbell */
- wmb();
--
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
next prev parent reply other threads:[~2018-04-03 2:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1521736009-23387-1-git-send-email-okaya@codeaurora.org>
2018-03-22 16:26 ` [PATCH v5 1/3] RDMA/bnxt_re: Eliminate duplicate barriers on weakly-ordered archs Sinan Kaya
2018-03-22 16:26 ` [PATCH v5 2/3] RDMA/i40iw: " Sinan Kaya
2018-03-23 19:15 ` Sinan Kaya
2018-03-22 16:26 ` [PATCH v5 3/3] RDMA/qedr: eliminate duplicate barriers on weakly-ordered archs #2 Sinan Kaya
2018-04-03 2:29 ` Sinan Kaya [this message]
2018-04-03 7:42 ` Kalderon, Michal
2018-04-03 17:47 ` Sinan Kaya
2018-04-03 20:03 ` Jason Gunthorpe
2018-04-04 11:54 ` Kalderon, Michal
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