From: Chuck Lever <chuck.lever@oracle.com>
To: linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org
Subject: [PATCH v1 14/18] xprtrdma: Use an llist to manage free rpcrdma_reps
Date: Tue, 06 Aug 2019 11:55:00 -0400 [thread overview]
Message-ID: <20190806155500.9529.30933.stgit@manet.1015granger.net> (raw)
In-Reply-To: <20190806155246.9529.14571.stgit@manet.1015granger.net>
rpcrdma_rep objects are removed from their free list by only a
single thread: the Receive completion handler. Thus that free list
can be converted to an llist, where a single-threaded consumer and
a multi-threaded producer (rpcrdma_buffer_put) can both access the
llist without the need for any serialization.
This eliminates spin lock contention between the Receive completion
handler and rpcrdma_buffer_get, and makes the rep consumer wait-
free.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
net/sunrpc/xprtrdma/verbs.c | 106 ++++++++++++++++++---------------------
net/sunrpc/xprtrdma/xprt_rdma.h | 6 +-
2 files changed, 53 insertions(+), 59 deletions(-)
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 15a77b3..4112b8a 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -74,6 +74,7 @@
* internal functions
*/
static void rpcrdma_sendctx_put_locked(struct rpcrdma_sendctx *sc);
+static void rpcrdma_reps_destroy(struct rpcrdma_buffer *buf);
static void rpcrdma_mrs_create(struct rpcrdma_xprt *r_xprt);
static void rpcrdma_mrs_destroy(struct rpcrdma_buffer *buf);
static void rpcrdma_mr_free(struct rpcrdma_mr *mr);
@@ -406,7 +407,6 @@ static void rpcrdma_xprt_drain(struct rpcrdma_xprt *r_xprt)
struct rpcrdma_ep *ep = &r_xprt->rx_ep;
struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
struct rpcrdma_req *req;
- struct rpcrdma_rep *rep;
cancel_work_sync(&buf->rb_refresh_worker);
@@ -430,8 +430,7 @@ static void rpcrdma_xprt_drain(struct rpcrdma_xprt *r_xprt)
/* The ULP is responsible for ensuring all DMA
* mappings and MRs are gone.
*/
- list_for_each_entry(rep, &buf->rb_recv_bufs, rr_list)
- rpcrdma_regbuf_dma_unmap(rep->rr_rdmabuf);
+ rpcrdma_reps_destroy(buf);
list_for_each_entry(req, &buf->rb_allreqs, rl_all) {
rpcrdma_regbuf_dma_unmap(req->rl_rdmabuf);
rpcrdma_regbuf_dma_unmap(req->rl_sendbuf);
@@ -1063,6 +1062,40 @@ static struct rpcrdma_rep *rpcrdma_rep_create(struct rpcrdma_xprt *r_xprt,
return NULL;
}
+static void rpcrdma_rep_destroy(struct rpcrdma_rep *rep)
+{
+ rpcrdma_regbuf_free(rep->rr_rdmabuf);
+ kfree(rep);
+}
+
+static struct rpcrdma_rep *rpcrdma_rep_get_locked(struct rpcrdma_buffer *buf)
+{
+ struct llist_node *node;
+
+ /* Calls to llist_del_first are required to be serialized */
+ node = llist_del_first(&buf->rb_free_reps);
+ if (!node)
+ return NULL;
+ return llist_entry(node, struct rpcrdma_rep, rr_node);
+}
+
+static void rpcrdma_rep_put(struct rpcrdma_buffer *buf,
+ struct rpcrdma_rep *rep)
+{
+ if (!rep->rr_temp)
+ llist_add(&rep->rr_node, &buf->rb_free_reps);
+ else
+ rpcrdma_rep_destroy(rep);
+}
+
+static void rpcrdma_reps_destroy(struct rpcrdma_buffer *buf)
+{
+ struct rpcrdma_rep *rep;
+
+ while ((rep = rpcrdma_rep_get_locked(buf)) != NULL)
+ rpcrdma_rep_destroy(rep);
+}
+
/**
* rpcrdma_buffer_create - Create initial set of req/rep objects
* @r_xprt: transport instance to (re)initialize
@@ -1098,7 +1131,7 @@ int rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
}
buf->rb_credits = 1;
- INIT_LIST_HEAD(&buf->rb_recv_bufs);
+ init_llist_head(&buf->rb_free_reps);
rc = rpcrdma_sendctxs_create(r_xprt);
if (rc)
@@ -1110,12 +1143,6 @@ int rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
return rc;
}
-static void rpcrdma_rep_destroy(struct rpcrdma_rep *rep)
-{
- rpcrdma_regbuf_free(rep->rr_rdmabuf);
- kfree(rep);
-}
-
/**
* rpcrdma_req_destroy - Destroy an rpcrdma_req object
* @req: unused object to be destroyed
@@ -1174,15 +1201,7 @@ void rpcrdma_req_destroy(struct rpcrdma_req *req)
cancel_work_sync(&buf->rb_refresh_worker);
rpcrdma_sendctxs_destroy(buf);
-
- while (!list_empty(&buf->rb_recv_bufs)) {
- struct rpcrdma_rep *rep;
-
- rep = list_first_entry(&buf->rb_recv_bufs,
- struct rpcrdma_rep, rr_list);
- list_del(&rep->rr_list);
- rpcrdma_rep_destroy(rep);
- }
+ rpcrdma_reps_destroy(buf);
while (!list_empty(&buf->rb_send_bufs)) {
struct rpcrdma_req *req;
@@ -1273,39 +1292,24 @@ struct rpcrdma_req *
*/
void rpcrdma_buffer_put(struct rpcrdma_buffer *buffers, struct rpcrdma_req *req)
{
- struct rpcrdma_rep *rep = req->rl_reply;
-
+ if (req->rl_reply)
+ rpcrdma_rep_put(buffers, req->rl_reply);
req->rl_reply = NULL;
spin_lock(&buffers->rb_lock);
list_add(&req->rl_list, &buffers->rb_send_bufs);
- if (rep) {
- if (!rep->rr_temp) {
- list_add(&rep->rr_list, &buffers->rb_recv_bufs);
- rep = NULL;
- }
- }
spin_unlock(&buffers->rb_lock);
- if (rep)
- rpcrdma_rep_destroy(rep);
}
-/*
- * Put reply buffers back into pool when not attached to
- * request. This happens in error conditions.
+/**
+ * rpcrdma_recv_buffer_put - Release rpcrdma_rep back to free list
+ * @rep: rep to release
+ *
+ * Used after error conditions.
*/
-void
-rpcrdma_recv_buffer_put(struct rpcrdma_rep *rep)
+void rpcrdma_recv_buffer_put(struct rpcrdma_rep *rep)
{
- struct rpcrdma_buffer *buffers = &rep->rr_rxprt->rx_buf;
-
- if (!rep->rr_temp) {
- spin_lock(&buffers->rb_lock);
- list_add(&rep->rr_list, &buffers->rb_recv_bufs);
- spin_unlock(&buffers->rb_lock);
- } else {
- rpcrdma_rep_destroy(rep);
- }
+ rpcrdma_rep_put(&rep->rr_rxprt->rx_buf, rep);
}
/* Returns a pointer to a rpcrdma_regbuf object, or NULL.
@@ -1461,22 +1465,10 @@ static void rpcrdma_regbuf_free(struct rpcrdma_regbuf *rb)
/* fast path: all needed reps can be found on the free list */
wr = NULL;
- spin_lock(&buf->rb_lock);
while (needed) {
- rep = list_first_entry_or_null(&buf->rb_recv_bufs,
- struct rpcrdma_rep, rr_list);
+ rep = rpcrdma_rep_get_locked(buf);
if (!rep)
- break;
-
- list_del(&rep->rr_list);
- rep->rr_recv_wr.next = wr;
- wr = &rep->rr_recv_wr;
- --needed;
- }
- spin_unlock(&buf->rb_lock);
-
- while (needed) {
- rep = rpcrdma_rep_create(r_xprt, temp);
+ rep = rpcrdma_rep_create(r_xprt, temp);
if (!rep)
break;
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index b388bb4..338da5f 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -47,6 +47,7 @@
#include <linux/atomic.h> /* atomic_t, etc */
#include <linux/kref.h> /* struct kref */
#include <linux/workqueue.h> /* struct work_struct */
+#include <linux/llist.h>
#include <rdma/rdma_cm.h> /* RDMA connection api */
#include <rdma/ib_verbs.h> /* RDMA verbs api */
@@ -205,7 +206,7 @@ struct rpcrdma_rep {
struct rpc_rqst *rr_rqst;
struct xdr_buf rr_hdrbuf;
struct xdr_stream rr_stream;
- struct list_head rr_list;
+ struct llist_node rr_node;
struct ib_recv_wr rr_recv_wr;
};
@@ -367,7 +368,6 @@ struct rpcrdma_req {
struct rpcrdma_buffer {
spinlock_t rb_lock;
struct list_head rb_send_bufs;
- struct list_head rb_recv_bufs;
struct list_head rb_mrs;
unsigned long rb_sc_head;
@@ -378,6 +378,8 @@ struct rpcrdma_buffer {
struct list_head rb_allreqs;
struct list_head rb_all_mrs;
+ struct llist_head rb_free_reps;
+
u32 rb_max_requests;
u32 rb_credits; /* most recent credit grant */
next prev parent reply other threads:[~2019-08-06 15:55 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-06 15:53 [PATCH v1 00/18] NFS/RDMA patches Chuck Lever
2019-08-06 15:53 ` [PATCH v1 01/18] xprtrdma: Refresh the documenting comment in frwr_ops.c Chuck Lever
2019-08-06 15:53 ` [PATCH v1 02/18] xprtrdma: Fix calculation of ri_max_segs again Chuck Lever
2019-08-06 15:54 ` [PATCH v1 03/18] xprtrdma: Boost maximum transport header size Chuck Lever
2019-08-06 15:54 ` [PATCH v1 04/18] xprtrdma: Boost client's max slot table size to match Linux server Chuck Lever
2019-08-06 15:54 ` [PATCH v1 05/18] xprtrdma: Rename CQE field in Receive trace points Chuck Lever
2019-08-06 15:54 ` [PATCH v1 06/18] xprtrdma: Rename rpcrdma_buffer::rb_all Chuck Lever
2019-08-06 15:54 ` [PATCH v1 07/18] xprtrdma: Toggle XPRT_CONGESTED in xprtrdma's slot methods Chuck Lever
2019-08-06 15:54 ` [PATCH v1 08/18] xprtrdma: Simplify rpcrdma_mr_pop Chuck Lever
2019-08-06 15:54 ` [PATCH v1 09/18] xprtrdma: Combine rpcrdma_mr_put and rpcrdma_mr_unmap_and_put Chuck Lever
2019-08-06 15:54 ` [PATCH v1 10/18] xprtrdma: Move rpcrdma_mr_get out of frwr_map Chuck Lever
2019-08-06 15:54 ` [PATCH v1 11/18] xprtrdma: Ensure creating an MR does not trigger FS writeback Chuck Lever
2019-08-06 15:54 ` [PATCH v1 12/18] xprtrdma: Cache free MRs in each rpcrdma_req Chuck Lever
2019-08-06 15:54 ` [PATCH v1 13/18] xprtrdma: Remove rpcrdma_buffer::rb_mrlock Chuck Lever
2019-08-06 15:55 ` Chuck Lever [this message]
2019-08-06 15:55 ` [PATCH v1 15/18] xprtrdma: Clean up xprt_rdma_set_connect_timeout() Chuck Lever
2019-08-06 15:55 ` [PATCH v1 16/18] xprtdma: Fix bc_max_slots return value Chuck Lever
2019-08-06 15:55 ` [PATCH v1 17/18] xprtrdma: Inline XDR chunk encoder functions Chuck Lever
2019-08-06 15:55 ` [PATCH v1 18/18] xprtrdma: Optimize rpcrdma_post_recvs() Chuck Lever
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=20190806155500.9529.30933.stgit@manet.1015granger.net \
--to=chuck.lever@oracle.com \
--cc=linux-nfs@vger.kernel.org \
--cc=linux-rdma@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
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;
as well as URLs for NNTP newsgroup(s).