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Date: Tue, 24 Feb 2009 17:30:33 -0800
From: Andy Grover <andy.grover@...cle.com>
To: netdev@...r.kernel.org
Cc: rds-devel@....oracle.com, general@...ts.openfabrics.org
Subject: [PATCH 16/26] RDS/IB: Implement IB-specific datagram send.
Specific to IB is a credits-based flow control mechanism, in
addition to the expected usage of the IB API to package outgoing
data into work requests.
Signed-off-by: Andy Grover <andy.grover@...cle.com>
---
net/rds/ib_send.c | 874 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 874 insertions(+), 0 deletions(-)
create mode 100644 net/rds/ib_send.c
diff --git a/net/rds/ib_send.c b/net/rds/ib_send.c
new file mode 100644
index 0000000..cb6c52c
--- /dev/null
+++ b/net/rds/ib_send.c
@@ -0,0 +1,874 @@
+/*
+ * Copyright (c) 2006 Oracle. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ * 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.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/in.h>
+#include <linux/device.h>
+#include <linux/dmapool.h>
+
+#include "rds.h"
+#include "rdma.h"
+#include "ib.h"
+
+static void rds_ib_send_rdma_complete(struct rds_message *rm,
+ int wc_status)
+{
+ int notify_status;
+
+ switch (wc_status) {
+ case IB_WC_WR_FLUSH_ERR:
+ return;
+
+ case IB_WC_SUCCESS:
+ notify_status = RDS_RDMA_SUCCESS;
+ break;
+
+ case IB_WC_REM_ACCESS_ERR:
+ notify_status = RDS_RDMA_REMOTE_ERROR;
+ break;
+
+ default:
+ notify_status = RDS_RDMA_OTHER_ERROR;
+ break;
+ }
+ rds_rdma_send_complete(rm, notify_status);
+}
+
+static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic,
+ struct rds_rdma_op *op)
+{
+ if (op->r_mapped) {
+ ib_dma_unmap_sg(ic->i_cm_id->device,
+ op->r_sg, op->r_nents,
+ op->r_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
+ op->r_mapped = 0;
+ }
+}
+
+static void rds_ib_send_unmap_rm(struct rds_ib_connection *ic,
+ struct rds_ib_send_work *send,
+ int wc_status)
+{
+ struct rds_message *rm = send->s_rm;
+
+ rdsdebug("ic %p send %p rm %p\n", ic, send, rm);
+
+ ib_dma_unmap_sg(ic->i_cm_id->device,
+ rm->m_sg, rm->m_nents,
+ DMA_TO_DEVICE);
+
+ if (rm->m_rdma_op != NULL) {
+ rds_ib_send_unmap_rdma(ic, rm->m_rdma_op);
+
+ /* If the user asked for a completion notification on this
+ * message, we can implement three different semantics:
+ * 1. Notify when we received the ACK on the RDS message
+ * that was queued with the RDMA. This provides reliable
+ * notification of RDMA status at the expense of a one-way
+ * packet delay.
+ * 2. Notify when the IB stack gives us the completion event for
+ * the RDMA operation.
+ * 3. Notify when the IB stack gives us the completion event for
+ * the accompanying RDS messages.
+ * Here, we implement approach #3. To implement approach #2,
+ * call rds_rdma_send_complete from the cq_handler. To implement #1,
+ * don't call rds_rdma_send_complete at all, and fall back to the notify
+ * handling in the ACK processing code.
+ *
+ * Note: There's no need to explicitly sync any RDMA buffers using
+ * ib_dma_sync_sg_for_cpu - the completion for the RDMA
+ * operation itself unmapped the RDMA buffers, which takes care
+ * of synching.
+ */
+ rds_ib_send_rdma_complete(rm, wc_status);
+
+ if (rm->m_rdma_op->r_write)
+ rds_stats_add(s_send_rdma_bytes, rm->m_rdma_op->r_bytes);
+ else
+ rds_stats_add(s_recv_rdma_bytes, rm->m_rdma_op->r_bytes);
+ }
+
+ /* If anyone waited for this message to get flushed out, wake
+ * them up now */
+ rds_message_unmapped(rm);
+
+ rds_message_put(rm);
+ send->s_rm = NULL;
+}
+
+void rds_ib_send_init_ring(struct rds_ib_connection *ic)
+{
+ struct rds_ib_send_work *send;
+ u32 i;
+
+ for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
+ struct ib_sge *sge;
+
+ send->s_rm = NULL;
+ send->s_op = NULL;
+
+ send->s_wr.wr_id = i;
+ send->s_wr.sg_list = send->s_sge;
+ send->s_wr.num_sge = 1;
+ send->s_wr.opcode = IB_WR_SEND;
+ send->s_wr.send_flags = 0;
+ send->s_wr.ex.imm_data = 0;
+
+ sge = rds_ib_data_sge(ic, send->s_sge);
+ sge->lkey = ic->i_mr->lkey;
+
+ sge = rds_ib_header_sge(ic, send->s_sge);
+ sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header));
+ sge->length = sizeof(struct rds_header);
+ sge->lkey = ic->i_mr->lkey;
+ }
+}
+
+void rds_ib_send_clear_ring(struct rds_ib_connection *ic)
+{
+ struct rds_ib_send_work *send;
+ u32 i;
+
+ for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
+ if (send->s_wr.opcode == 0xdead)
+ continue;
+ if (send->s_rm)
+ rds_ib_send_unmap_rm(ic, send, IB_WC_WR_FLUSH_ERR);
+ if (send->s_op)
+ rds_ib_send_unmap_rdma(ic, send->s_op);
+ }
+}
+
+/*
+ * The _oldest/_free ring operations here race cleanly with the alloc/unalloc
+ * operations performed in the send path. As the sender allocs and potentially
+ * unallocs the next free entry in the ring it doesn't alter which is
+ * the next to be freed, which is what this is concerned with.
+ */
+void rds_ib_send_cq_comp_handler(struct ib_cq *cq, void *context)
+{
+ struct rds_connection *conn = context;
+ struct rds_ib_connection *ic = conn->c_transport_data;
+ struct ib_wc wc;
+ struct rds_ib_send_work *send;
+ u32 completed;
+ u32 oldest;
+ u32 i = 0;
+ int ret;
+
+ rdsdebug("cq %p conn %p\n", cq, conn);
+ rds_ib_stats_inc(s_ib_tx_cq_call);
+ ret = ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
+ if (ret)
+ rdsdebug("ib_req_notify_cq send failed: %d\n", ret);
+
+ while (ib_poll_cq(cq, 1, &wc) > 0) {
+ rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n",
+ (unsigned long long)wc.wr_id, wc.status, wc.byte_len,
+ be32_to_cpu(wc.ex.imm_data));
+ rds_ib_stats_inc(s_ib_tx_cq_event);
+
+ if (wc.wr_id == RDS_IB_ACK_WR_ID) {
+ if (ic->i_ack_queued + HZ/2 < jiffies)
+ rds_ib_stats_inc(s_ib_tx_stalled);
+ rds_ib_ack_send_complete(ic);
+ continue;
+ }
+
+ oldest = rds_ib_ring_oldest(&ic->i_send_ring);
+
+ completed = rds_ib_ring_completed(&ic->i_send_ring, wc.wr_id, oldest);
+
+ for (i = 0; i < completed; i++) {
+ send = &ic->i_sends[oldest];
+
+ /* In the error case, wc.opcode sometimes contains garbage */
+ switch (send->s_wr.opcode) {
+ case IB_WR_SEND:
+ if (send->s_rm)
+ rds_ib_send_unmap_rm(ic, send, wc.status);
+ break;
+ case IB_WR_RDMA_WRITE:
+ case IB_WR_RDMA_READ:
+ /* Nothing to be done - the SG list will be unmapped
+ * when the SEND completes. */
+ break;
+ default:
+ if (printk_ratelimit())
+ printk(KERN_NOTICE
+ "RDS/IB: %s: unexpected opcode 0x%x in WR!\n",
+ __func__, send->s_wr.opcode);
+ break;
+ }
+
+ send->s_wr.opcode = 0xdead;
+ send->s_wr.num_sge = 1;
+ if (send->s_queued + HZ/2 < jiffies)
+ rds_ib_stats_inc(s_ib_tx_stalled);
+
+ /* If a RDMA operation produced an error, signal this right
+ * away. If we don't, the subsequent SEND that goes with this
+ * RDMA will be canceled with ERR_WFLUSH, and the application
+ * never learn that the RDMA failed. */
+ if (unlikely(wc.status == IB_WC_REM_ACCESS_ERR && send->s_op)) {
+ struct rds_message *rm;
+
+ rm = rds_send_get_message(conn, send->s_op);
+ if (rm)
+ rds_ib_send_rdma_complete(rm, wc.status);
+ }
+
+ oldest = (oldest + 1) % ic->i_send_ring.w_nr;
+ }
+
+ rds_ib_ring_free(&ic->i_send_ring, completed);
+
+ if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags)
+ || test_bit(0, &conn->c_map_queued))
+ queue_delayed_work(rds_wq, &conn->c_send_w, 0);
+
+ /* We expect errors as the qp is drained during shutdown */
+ if (wc.status != IB_WC_SUCCESS && rds_conn_up(conn)) {
+ rds_ib_conn_error(conn,
+ "send completion on %pI4 "
+ "had status %u, disconnecting and reconnecting\n",
+ &conn->c_faddr, wc.status);
+ }
+ }
+}
+
+/*
+ * This is the main function for allocating credits when sending
+ * messages.
+ *
+ * Conceptually, we have two counters:
+ * - send credits: this tells us how many WRs we're allowed
+ * to submit without overruning the reciever's queue. For
+ * each SEND WR we post, we decrement this by one.
+ *
+ * - posted credits: this tells us how many WRs we recently
+ * posted to the receive queue. This value is transferred
+ * to the peer as a "credit update" in a RDS header field.
+ * Every time we transmit credits to the peer, we subtract
+ * the amount of transferred credits from this counter.
+ *
+ * It is essential that we avoid situations where both sides have
+ * exhausted their send credits, and are unable to send new credits
+ * to the peer. We achieve this by requiring that we send at least
+ * one credit update to the peer before exhausting our credits.
+ * When new credits arrive, we subtract one credit that is withheld
+ * until we've posted new buffers and are ready to transmit these
+ * credits (see rds_ib_send_add_credits below).
+ *
+ * The RDS send code is essentially single-threaded; rds_send_xmit
+ * grabs c_send_lock to ensure exclusive access to the send ring.
+ * However, the ACK sending code is independent and can race with
+ * message SENDs.
+ *
+ * In the send path, we need to update the counters for send credits
+ * and the counter of posted buffers atomically - when we use the
+ * last available credit, we cannot allow another thread to race us
+ * and grab the posted credits counter. Hence, we have to use a
+ * spinlock to protect the credit counter, or use atomics.
+ *
+ * Spinlocks shared between the send and the receive path are bad,
+ * because they create unnecessary delays. An early implementation
+ * using a spinlock showed a 5% degradation in throughput at some
+ * loads.
+ *
+ * This implementation avoids spinlocks completely, putting both
+ * counters into a single atomic, and updating that atomic using
+ * atomic_add (in the receive path, when receiving fresh credits),
+ * and using atomic_cmpxchg when updating the two counters.
+ */
+int rds_ib_send_grab_credits(struct rds_ib_connection *ic,
+ u32 wanted, u32 *adv_credits, int need_posted)
+{
+ unsigned int avail, posted, got = 0, advertise;
+ long oldval, newval;
+
+ *adv_credits = 0;
+ if (!ic->i_flowctl)
+ return wanted;
+
+try_again:
+ advertise = 0;
+ oldval = newval = atomic_read(&ic->i_credits);
+ posted = IB_GET_POST_CREDITS(oldval);
+ avail = IB_GET_SEND_CREDITS(oldval);
+
+ rdsdebug("rds_ib_send_grab_credits(%u): credits=%u posted=%u\n",
+ wanted, avail, posted);
+
+ /* The last credit must be used to send a credit update. */
+ if (avail && !posted)
+ avail--;
+
+ if (avail < wanted) {
+ struct rds_connection *conn = ic->i_cm_id->context;
+
+ /* Oops, there aren't that many credits left! */
+ set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
+ got = avail;
+ } else {
+ /* Sometimes you get what you want, lalala. */
+ got = wanted;
+ }
+ newval -= IB_SET_SEND_CREDITS(got);
+
+ /*
+ * If need_posted is non-zero, then the caller wants
+ * the posted regardless of whether any send credits are
+ * available.
+ */
+ if (posted && (got || need_posted)) {
+ advertise = min_t(unsigned int, posted, RDS_MAX_ADV_CREDIT);
+ newval -= IB_SET_POST_CREDITS(advertise);
+ }
+
+ /* Finally bill everything */
+ if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval)
+ goto try_again;
+
+ *adv_credits = advertise;
+ return got;
+}
+
+void rds_ib_send_add_credits(struct rds_connection *conn, unsigned int credits)
+{
+ struct rds_ib_connection *ic = conn->c_transport_data;
+
+ if (credits == 0)
+ return;
+
+ rdsdebug("rds_ib_send_add_credits(%u): current=%u%s\n",
+ credits,
+ IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)),
+ test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : "");
+
+ atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits);
+ if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags))
+ queue_delayed_work(rds_wq, &conn->c_send_w, 0);
+
+ WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384);
+
+ rds_ib_stats_inc(s_ib_rx_credit_updates);
+}
+
+void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted)
+{
+ struct rds_ib_connection *ic = conn->c_transport_data;
+
+ if (posted == 0)
+ return;
+
+ atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits);
+
+ /* Decide whether to send an update to the peer now.
+ * If we would send a credit update for every single buffer we
+ * post, we would end up with an ACK storm (ACK arrives,
+ * consumes buffer, we refill the ring, send ACK to remote
+ * advertising the newly posted buffer... ad inf)
+ *
+ * Performance pretty much depends on how often we send
+ * credit updates - too frequent updates mean lots of ACKs.
+ * Too infrequent updates, and the peer will run out of
+ * credits and has to throttle.
+ * For the time being, 16 seems to be a good compromise.
+ */
+ if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16)
+ set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
+}
+
+static inline void
+rds_ib_xmit_populate_wr(struct rds_ib_connection *ic,
+ struct rds_ib_send_work *send, unsigned int pos,
+ unsigned long buffer, unsigned int length,
+ int send_flags)
+{
+ struct ib_sge *sge;
+
+ WARN_ON(pos != send - ic->i_sends);
+
+ send->s_wr.send_flags = send_flags;
+ send->s_wr.opcode = IB_WR_SEND;
+ send->s_wr.num_sge = 2;
+ send->s_wr.next = NULL;
+ send->s_queued = jiffies;
+ send->s_op = NULL;
+
+ if (length != 0) {
+ sge = rds_ib_data_sge(ic, send->s_sge);
+ sge->addr = buffer;
+ sge->length = length;
+ sge->lkey = ic->i_mr->lkey;
+
+ sge = rds_ib_header_sge(ic, send->s_sge);
+ } else {
+ /* We're sending a packet with no payload. There is only
+ * one SGE */
+ send->s_wr.num_sge = 1;
+ sge = &send->s_sge[0];
+ }
+
+ sge->addr = ic->i_send_hdrs_dma + (pos * sizeof(struct rds_header));
+ sge->length = sizeof(struct rds_header);
+ sge->lkey = ic->i_mr->lkey;
+}
+
+/*
+ * This can be called multiple times for a given message. The first time
+ * we see a message we map its scatterlist into the IB device so that
+ * we can provide that mapped address to the IB scatter gather entries
+ * in the IB work requests. We translate the scatterlist into a series
+ * of work requests that fragment the message. These work requests complete
+ * in order so we pass ownership of the message to the completion handler
+ * once we send the final fragment.
+ *
+ * The RDS core uses the c_send_lock to only enter this function once
+ * per connection. This makes sure that the tx ring alloc/unalloc pairs
+ * don't get out of sync and confuse the ring.
+ */
+int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
+ unsigned int hdr_off, unsigned int sg, unsigned int off)
+{
+ struct rds_ib_connection *ic = conn->c_transport_data;
+ struct ib_device *dev = ic->i_cm_id->device;
+ struct rds_ib_send_work *send = NULL;
+ struct rds_ib_send_work *first;
+ struct rds_ib_send_work *prev;
+ struct ib_send_wr *failed_wr;
+ struct scatterlist *scat;
+ u32 pos;
+ u32 i;
+ u32 work_alloc;
+ u32 credit_alloc;
+ u32 posted;
+ u32 adv_credits = 0;
+ int send_flags = 0;
+ int sent;
+ int ret;
+ int flow_controlled = 0;
+
+ BUG_ON(off % RDS_FRAG_SIZE);
+ BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header));
+
+ /* FIXME we may overallocate here */
+ if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0)
+ i = 1;
+ else
+ i = ceil(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE);
+
+ work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
+ if (work_alloc == 0) {
+ set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
+ rds_ib_stats_inc(s_ib_tx_ring_full);
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ credit_alloc = work_alloc;
+ if (ic->i_flowctl) {
+ credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0);
+ adv_credits += posted;
+ if (credit_alloc < work_alloc) {
+ rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc);
+ work_alloc = credit_alloc;
+ flow_controlled++;
+ }
+ if (work_alloc == 0) {
+ rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
+ rds_ib_stats_inc(s_ib_tx_throttle);
+ ret = -ENOMEM;
+ goto out;
+ }
+ }
+
+ /* map the message the first time we see it */
+ if (ic->i_rm == NULL) {
+ /*
+ printk(KERN_NOTICE "rds_ib_xmit prep msg dport=%u flags=0x%x len=%d\n",
+ be16_to_cpu(rm->m_inc.i_hdr.h_dport),
+ rm->m_inc.i_hdr.h_flags,
+ be32_to_cpu(rm->m_inc.i_hdr.h_len));
+ */
+ if (rm->m_nents) {
+ rm->m_count = ib_dma_map_sg(dev,
+ rm->m_sg, rm->m_nents, DMA_TO_DEVICE);
+ rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->m_count);
+ if (rm->m_count == 0) {
+ rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
+ rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
+ ret = -ENOMEM; /* XXX ? */
+ goto out;
+ }
+ } else {
+ rm->m_count = 0;
+ }
+
+ ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
+ ic->i_unsignaled_bytes = rds_ib_sysctl_max_unsig_bytes;
+ rds_message_addref(rm);
+ ic->i_rm = rm;
+
+ /* Finalize the header */
+ if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags))
+ rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED;
+ if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
+ rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
+
+ /* If it has a RDMA op, tell the peer we did it. This is
+ * used by the peer to release use-once RDMA MRs. */
+ if (rm->m_rdma_op) {
+ struct rds_ext_header_rdma ext_hdr;
+
+ ext_hdr.h_rdma_rkey = cpu_to_be32(rm->m_rdma_op->r_key);
+ rds_message_add_extension(&rm->m_inc.i_hdr,
+ RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr));
+ }
+ if (rm->m_rdma_cookie) {
+ rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr,
+ rds_rdma_cookie_key(rm->m_rdma_cookie),
+ rds_rdma_cookie_offset(rm->m_rdma_cookie));
+ }
+
+ /* Note - rds_ib_piggyb_ack clears the ACK_REQUIRED bit, so
+ * we should not do this unless we have a chance of at least
+ * sticking the header into the send ring. Which is why we
+ * should call rds_ib_ring_alloc first. */
+ rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_ib_piggyb_ack(ic));
+ rds_message_make_checksum(&rm->m_inc.i_hdr);
+
+ /*
+ * Update adv_credits since we reset the ACK_REQUIRED bit.
+ */
+ rds_ib_send_grab_credits(ic, 0, &posted, 1);
+ adv_credits += posted;
+ BUG_ON(adv_credits > 255);
+ } else if (ic->i_rm != rm)
+ BUG();
+
+ send = &ic->i_sends[pos];
+ first = send;
+ prev = NULL;
+ scat = &rm->m_sg[sg];
+ sent = 0;
+ i = 0;
+
+ /* Sometimes you want to put a fence between an RDMA
+ * READ and the following SEND.
+ * We could either do this all the time
+ * or when requested by the user. Right now, we let
+ * the application choose.
+ */
+ if (rm->m_rdma_op && rm->m_rdma_op->r_fence)
+ send_flags = IB_SEND_FENCE;
+
+ /*
+ * We could be copying the header into the unused tail of the page.
+ * That would need to be changed in the future when those pages might
+ * be mapped userspace pages or page cache pages. So instead we always
+ * use a second sge and our long-lived ring of mapped headers. We send
+ * the header after the data so that the data payload can be aligned on
+ * the receiver.
+ */
+
+ /* handle a 0-len message */
+ if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0) {
+ rds_ib_xmit_populate_wr(ic, send, pos, 0, 0, send_flags);
+ goto add_header;
+ }
+
+ /* if there's data reference it with a chain of work reqs */
+ for (; i < work_alloc && scat != &rm->m_sg[rm->m_count]; i++) {
+ unsigned int len;
+
+ send = &ic->i_sends[pos];
+
+ len = min(RDS_FRAG_SIZE, ib_sg_dma_len(dev, scat) - off);
+ rds_ib_xmit_populate_wr(ic, send, pos,
+ ib_sg_dma_address(dev, scat) + off, len,
+ send_flags);
+
+ /*
+ * We want to delay signaling completions just enough to get
+ * the batching benefits but not so much that we create dead time
+ * on the wire.
+ */
+ if (ic->i_unsignaled_wrs-- == 0) {
+ ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
+ send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
+ }
+
+ ic->i_unsignaled_bytes -= len;
+ if (ic->i_unsignaled_bytes <= 0) {
+ ic->i_unsignaled_bytes = rds_ib_sysctl_max_unsig_bytes;
+ send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
+ }
+
+ /*
+ * Always signal the last one if we're stopping due to flow control.
+ */
+ if (flow_controlled && i == (work_alloc-1))
+ send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
+
+ rdsdebug("send %p wr %p num_sge %u next %p\n", send,
+ &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
+
+ sent += len;
+ off += len;
+ if (off == ib_sg_dma_len(dev, scat)) {
+ scat++;
+ off = 0;
+ }
+
+add_header:
+ /* Tack on the header after the data. The header SGE should already
+ * have been set up to point to the right header buffer. */
+ memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
+
+ if (0) {
+ struct rds_header *hdr = &ic->i_send_hdrs[pos];
+
+ printk(KERN_NOTICE "send WR dport=%u flags=0x%x len=%d\n",
+ be16_to_cpu(hdr->h_dport),
+ hdr->h_flags,
+ be32_to_cpu(hdr->h_len));
+ }
+ if (adv_credits) {
+ struct rds_header *hdr = &ic->i_send_hdrs[pos];
+
+ /* add credit and redo the header checksum */
+ hdr->h_credit = adv_credits;
+ rds_message_make_checksum(hdr);
+ adv_credits = 0;
+ rds_ib_stats_inc(s_ib_tx_credit_updates);
+ }
+
+ if (prev)
+ prev->s_wr.next = &send->s_wr;
+ prev = send;
+
+ pos = (pos + 1) % ic->i_send_ring.w_nr;
+ }
+
+ /* Account the RDS header in the number of bytes we sent, but just once.
+ * The caller has no concept of fragmentation. */
+ if (hdr_off == 0)
+ sent += sizeof(struct rds_header);
+
+ /* if we finished the message then send completion owns it */
+ if (scat == &rm->m_sg[rm->m_count]) {
+ prev->s_rm = ic->i_rm;
+ prev->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
+ ic->i_rm = NULL;
+ }
+
+ if (i < work_alloc) {
+ rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
+ work_alloc = i;
+ }
+ if (ic->i_flowctl && i < credit_alloc)
+ rds_ib_send_add_credits(conn, credit_alloc - i);
+
+ /* XXX need to worry about failed_wr and partial sends. */
+ failed_wr = &first->s_wr;
+ ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
+ rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
+ first, &first->s_wr, ret, failed_wr);
+ BUG_ON(failed_wr != &first->s_wr);
+ if (ret) {
+ printk(KERN_WARNING "RDS/IB: ib_post_send to %pI4 "
+ "returned %d\n", &conn->c_faddr, ret);
+ rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
+ if (prev->s_rm) {
+ ic->i_rm = prev->s_rm;
+ prev->s_rm = NULL;
+ }
+ /* Finesse this later */
+ BUG();
+ goto out;
+ }
+
+ ret = sent;
+out:
+ BUG_ON(adv_credits);
+ return ret;
+}
+
+int rds_ib_xmit_rdma(struct rds_connection *conn, struct rds_rdma_op *op)
+{
+ struct rds_ib_connection *ic = conn->c_transport_data;
+ struct rds_ib_send_work *send = NULL;
+ struct rds_ib_send_work *first;
+ struct rds_ib_send_work *prev;
+ struct ib_send_wr *failed_wr;
+ struct rds_ib_device *rds_ibdev;
+ struct scatterlist *scat;
+ unsigned long len;
+ u64 remote_addr = op->r_remote_addr;
+ u32 pos;
+ u32 work_alloc;
+ u32 i;
+ u32 j;
+ int sent;
+ int ret;
+ int num_sge;
+
+ rds_ibdev = ib_get_client_data(ic->i_cm_id->device, &rds_ib_client);
+
+ /* map the message the first time we see it */
+ if (!op->r_mapped) {
+ op->r_count = ib_dma_map_sg(ic->i_cm_id->device,
+ op->r_sg, op->r_nents, (op->r_write) ?
+ DMA_TO_DEVICE : DMA_FROM_DEVICE);
+ rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->r_count);
+ if (op->r_count == 0) {
+ rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
+ ret = -ENOMEM; /* XXX ? */
+ goto out;
+ }
+
+ op->r_mapped = 1;
+ }
+
+ /*
+ * Instead of knowing how to return a partial rdma read/write we insist that there
+ * be enough work requests to send the entire message.
+ */
+ i = ceil(op->r_count, rds_ibdev->max_sge);
+
+ work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
+ if (work_alloc != i) {
+ rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
+ rds_ib_stats_inc(s_ib_tx_ring_full);
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ send = &ic->i_sends[pos];
+ first = send;
+ prev = NULL;
+ scat = &op->r_sg[0];
+ sent = 0;
+ num_sge = op->r_count;
+
+ for (i = 0; i < work_alloc && scat != &op->r_sg[op->r_count]; i++) {
+ send->s_wr.send_flags = 0;
+ send->s_queued = jiffies;
+ /*
+ * We want to delay signaling completions just enough to get
+ * the batching benefits but not so much that we create dead time on the wire.
+ */
+ if (ic->i_unsignaled_wrs-- == 0) {
+ ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
+ send->s_wr.send_flags = IB_SEND_SIGNALED;
+ }
+
+ send->s_wr.opcode = op->r_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ;
+ send->s_wr.wr.rdma.remote_addr = remote_addr;
+ send->s_wr.wr.rdma.rkey = op->r_key;
+ send->s_op = op;
+
+ if (num_sge > rds_ibdev->max_sge) {
+ send->s_wr.num_sge = rds_ibdev->max_sge;
+ num_sge -= rds_ibdev->max_sge;
+ } else {
+ send->s_wr.num_sge = num_sge;
+ }
+
+ send->s_wr.next = NULL;
+
+ if (prev)
+ prev->s_wr.next = &send->s_wr;
+
+ for (j = 0; j < send->s_wr.num_sge && scat != &op->r_sg[op->r_count]; j++) {
+ len = ib_sg_dma_len(ic->i_cm_id->device, scat);
+ send->s_sge[j].addr =
+ ib_sg_dma_address(ic->i_cm_id->device, scat);
+ send->s_sge[j].length = len;
+ send->s_sge[j].lkey = ic->i_mr->lkey;
+
+ sent += len;
+ rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
+
+ remote_addr += len;
+ scat++;
+ }
+
+ rdsdebug("send %p wr %p num_sge %u next %p\n", send,
+ &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
+
+ prev = send;
+ if (++send == &ic->i_sends[ic->i_send_ring.w_nr])
+ send = ic->i_sends;
+ }
+
+ /* if we finished the message then send completion owns it */
+ if (scat == &op->r_sg[op->r_count])
+ prev->s_wr.send_flags = IB_SEND_SIGNALED;
+
+ if (i < work_alloc) {
+ rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
+ work_alloc = i;
+ }
+
+ failed_wr = &first->s_wr;
+ ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
+ rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
+ first, &first->s_wr, ret, failed_wr);
+ BUG_ON(failed_wr != &first->s_wr);
+ if (ret) {
+ printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI4 "
+ "returned %d\n", &conn->c_faddr, ret);
+ rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
+ goto out;
+ }
+
+ if (unlikely(failed_wr != &first->s_wr)) {
+ printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
+ BUG_ON(failed_wr != &first->s_wr);
+ }
+
+
+out:
+ return ret;
+}
+
+void rds_ib_xmit_complete(struct rds_connection *conn)
+{
+ struct rds_ib_connection *ic = conn->c_transport_data;
+
+ /* We may have a pending ACK or window update we were unable
+ * to send previously (due to flow control). Try again. */
+ rds_ib_attempt_ack(ic);
+}
--
1.5.6.3
--
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