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xprtrdma: Allocate req's regbufs at xprt create time

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Allocating an rpcrdma_req's regbufs at xprt create time enables
a pair of micro-optimizations:

First, if these regbufs are always there, we can eliminate two
conditional branches from the hot xprt_rdma_allocate path.

Second, by allocating a 1KB buffer, it places a lower bound on the
size of these buffers, without adding yet another conditional
branch. The lower bound reduces the number of hardway re-
allocations. In fact, for some workloads it completely eliminates
hardway allocations.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever
2019-04-24 09:39:21 -04:00
committed by Anna Schumaker
parent 8cec3dba76
commit bb93a1ae2b
4 changed files with 33 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
net/sunrpc/xprtrdma/verbs.c
View File

@@ -998,11 +998,13 @@ rpcrdma_mr_refresh_worker(struct work_struct *work)
/**
* rpcrdma_req_create - Allocate an rpcrdma_req object
* @r_xprt: controlling r_xprt
* @size: initial size, in bytes, of send and receive buffers
* @flags: GFP flags passed to memory allocators
*
* Returns an allocated and fully initialized rpcrdma_req or NULL.
*/
struct rpcrdma_req *rpcrdma_req_create(struct rpcrdma_xprt *r_xprt, gfp_t flags)
struct rpcrdma_req *rpcrdma_req_create(struct rpcrdma_xprt *r_xprt, size_t size,
gfp_t flags)
{
struct rpcrdma_buffer *buffer = &r_xprt->rx_buf;
struct rpcrdma_regbuf *rb;
@@ -1010,22 +1012,37 @@ struct rpcrdma_req *rpcrdma_req_create(struct rpcrdma_xprt *r_xprt, gfp_t flags)
req = kzalloc(sizeof(*req), flags);
if (req == NULL)
return NULL;
goto out1;
rb = rpcrdma_alloc_regbuf(RPCRDMA_HDRBUF_SIZE, DMA_TO_DEVICE, flags);
if (!rb) {
kfree(req);
return NULL;
}
if (!rb)
goto out2;
req->rl_rdmabuf = rb;
xdr_buf_init(&req->rl_hdrbuf, rdmab_data(rb), rdmab_length(rb));
req->rl_sendbuf = rpcrdma_alloc_regbuf(size, DMA_TO_DEVICE, flags);
if (!req->rl_sendbuf)
goto out3;
req->rl_recvbuf = rpcrdma_alloc_regbuf(size, DMA_NONE, flags);
if (!req->rl_recvbuf)
goto out4;
req->rl_buffer = buffer;
INIT_LIST_HEAD(&req->rl_registered);
spin_lock(&buffer->rb_lock);
list_add(&req->rl_all, &buffer->rb_allreqs);
spin_unlock(&buffer->rb_lock);
return req;
out4:
kfree(req->rl_sendbuf);
out3:
kfree(req->rl_rdmabuf);
out2:
kfree(req);
out1:
return NULL;
}
static bool rpcrdma_rep_create(struct rpcrdma_xprt *r_xprt, bool temp)
@@ -1090,7 +1107,8 @@ rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
for (i = 0; i < buf->rb_max_requests; i++) {
struct rpcrdma_req *req;
req = rpcrdma_req_create(r_xprt, GFP_KERNEL);
req = rpcrdma_req_create(r_xprt, RPCRDMA_V1_DEF_INLINE_SIZE,
GFP_KERNEL);
if (!req)
goto out;
list_add(&req->rl_list, &buf->rb_send_bufs);