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linux/drivers/infiniband/sw/rdmavt/rc.c
Kamenee Arumugam f592ae3c99 IB/rdmavt: Fracture single lock used for posting and processing RWQEs
Usage of single lock prevents fetching posted and processing receive work
queue entries from progressing simultaneously and impacts overall
performance.

Fracture the single lock used for posting and processing Receive Work
Queue Entries (RWQEs) to allow the circular buffer to be filled and
emptied at the same time. Two new spinlocks - one for the producers and
one for the consumers used for posting and processing RWQEs simultaneously
and the two indices are define on two different cache lines. The threshold
count is used to avoid reading other index in different cache line every
time.

Signed-off-by: Harish Chegondi <harish.chegondi@intel.com>
Signed-off-by: Kamenee Arumugam <kamenee.arumugam@intel.com>
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
2019-06-28 22:32:16 -03:00

210 lines
6.4 KiB
C

/*
* Copyright(c) 2016 Intel Corporation.
*
* This file is provided under a dual BSD/GPLv2 license. When using or
* redistributing this file, you may do so under either license.
*
* GPL LICENSE SUMMARY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* BSD LICENSE
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* - Neither the name of Intel Corporation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <rdma/rdmavt_qp.h>
#include <rdma/ib_hdrs.h>
/*
* Convert the AETH credit code into the number of credits.
*/
static const u16 credit_table[31] = {
0, /* 0 */
1, /* 1 */
2, /* 2 */
3, /* 3 */
4, /* 4 */
6, /* 5 */
8, /* 6 */
12, /* 7 */
16, /* 8 */
24, /* 9 */
32, /* A */
48, /* B */
64, /* C */
96, /* D */
128, /* E */
192, /* F */
256, /* 10 */
384, /* 11 */
512, /* 12 */
768, /* 13 */
1024, /* 14 */
1536, /* 15 */
2048, /* 16 */
3072, /* 17 */
4096, /* 18 */
6144, /* 19 */
8192, /* 1A */
12288, /* 1B */
16384, /* 1C */
24576, /* 1D */
32768 /* 1E */
};
/**
* rvt_compute_aeth - compute the AETH (syndrome + MSN)
* @qp: the queue pair to compute the AETH for
*
* Returns the AETH.
*/
__be32 rvt_compute_aeth(struct rvt_qp *qp)
{
u32 aeth = qp->r_msn & IB_MSN_MASK;
if (qp->ibqp.srq) {
/*
* Shared receive queues don't generate credits.
* Set the credit field to the invalid value.
*/
aeth |= IB_AETH_CREDIT_INVAL << IB_AETH_CREDIT_SHIFT;
} else {
u32 min, max, x;
u32 credits;
u32 head;
u32 tail;
credits = READ_ONCE(qp->r_rq.kwq->count);
if (credits == 0) {
/* sanity check pointers before trusting them */
if (qp->ip) {
head = RDMA_READ_UAPI_ATOMIC(qp->r_rq.wq->head);
tail = RDMA_READ_UAPI_ATOMIC(qp->r_rq.wq->tail);
} else {
head = READ_ONCE(qp->r_rq.kwq->head);
tail = READ_ONCE(qp->r_rq.kwq->tail);
}
if (head >= qp->r_rq.size)
head = 0;
if (tail >= qp->r_rq.size)
tail = 0;
/*
* Compute the number of credits available (RWQEs).
* There is a small chance that the pair of reads are
* not atomic, which is OK, since the fuzziness is
* resolved as further ACKs go out.
*/
credits = head - tail;
if ((int)credits < 0)
credits += qp->r_rq.size;
}
/*
* Binary search the credit table to find the code to
* use.
*/
min = 0;
max = 31;
for (;;) {
x = (min + max) / 2;
if (credit_table[x] == credits)
break;
if (credit_table[x] > credits) {
max = x;
} else {
if (min == x)
break;
min = x;
}
}
aeth |= x << IB_AETH_CREDIT_SHIFT;
}
return cpu_to_be32(aeth);
}
EXPORT_SYMBOL(rvt_compute_aeth);
/**
* rvt_get_credit - flush the send work queue of a QP
* @qp: the qp who's send work queue to flush
* @aeth: the Acknowledge Extended Transport Header
*
* The QP s_lock should be held.
*/
void rvt_get_credit(struct rvt_qp *qp, u32 aeth)
{
struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);
u32 credit = (aeth >> IB_AETH_CREDIT_SHIFT) & IB_AETH_CREDIT_MASK;
lockdep_assert_held(&qp->s_lock);
/*
* If the credit is invalid, we can send
* as many packets as we like. Otherwise, we have to
* honor the credit field.
*/
if (credit == IB_AETH_CREDIT_INVAL) {
if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT)) {
qp->s_flags |= RVT_S_UNLIMITED_CREDIT;
if (qp->s_flags & RVT_S_WAIT_SSN_CREDIT) {
qp->s_flags &= ~RVT_S_WAIT_SSN_CREDIT;
rdi->driver_f.schedule_send(qp);
}
}
} else if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT)) {
/* Compute new LSN (i.e., MSN + credit) */
credit = (aeth + credit_table[credit]) & IB_MSN_MASK;
if (rvt_cmp_msn(credit, qp->s_lsn) > 0) {
qp->s_lsn = credit;
if (qp->s_flags & RVT_S_WAIT_SSN_CREDIT) {
qp->s_flags &= ~RVT_S_WAIT_SSN_CREDIT;
rdi->driver_f.schedule_send(qp);
}
}
}
}
EXPORT_SYMBOL(rvt_get_credit);
/* rvt_restart_sge - rewind the sge state for a wqe */
u32 rvt_restart_sge(struct rvt_sge_state *ss, struct rvt_swqe *wqe, u32 len)
{
ss->sge = wqe->sg_list[0];
ss->sg_list = wqe->sg_list + 1;
ss->num_sge = wqe->wr.num_sge;
ss->total_len = wqe->length;
rvt_skip_sge(ss, len, false);
return wqe->length - len;
}
EXPORT_SYMBOL(rvt_restart_sge);