On Mon, May 18, 2009 at 05:47:56PM -0400, Trond Myklebust wrote:
> Ensure that deferred requests are accounted for correctly by the write
> space reservation mechanism. In order to avoid double counting, remove the
> reservation when we defer the request, and save any calculated value, so
> that we can restore it when the request is requeued.
I like that it does the addition to xpt_reserved in just one place
instead of two, and carrying over the reserved_space is nice, but I
don't understand the "double accounting" comment--where exactly is
something counted twice?
--b.
>
> Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
> ---
>
> include/linux/sunrpc/svc.h | 1 +
> net/sunrpc/svc_xprt.c | 10 +++++-----
> 2 files changed, 6 insertions(+), 5 deletions(-)
>
>
> diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
> index 2a30775..2c373d8 100644
> --- a/include/linux/sunrpc/svc.h
> +++ b/include/linux/sunrpc/svc.h
> @@ -341,6 +341,7 @@ struct svc_deferred_req {
> union svc_addr_u daddr; /* where reply must come from */
> struct cache_deferred_req handle;
> size_t xprt_hlen;
> + int reserved_space;
> int argslen;
> __be32 args[0];
> };
> diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
> index c200d92..daa1f27 100644
> --- a/net/sunrpc/svc_xprt.c
> +++ b/net/sunrpc/svc_xprt.c
> @@ -299,7 +299,6 @@ static void svc_thread_dequeue(struct svc_pool *pool, struct svc_rqst *rqstp)
> */
> void svc_xprt_enqueue(struct svc_xprt *xprt)
> {
> - struct svc_serv *serv = xprt->xpt_server;
> struct svc_pool *pool;
> struct svc_rqst *rqstp;
> int cpu;
> @@ -376,8 +375,6 @@ void svc_xprt_enqueue(struct svc_xprt *xprt)
> rqstp, rqstp->rq_xprt);
> rqstp->rq_xprt = xprt;
> svc_xprt_get(xprt);
> - rqstp->rq_reserved = serv->sv_max_mesg;
> - atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved);
> rqstp->rq_waking = 1;
> pool->sp_nwaking++;
> pool->sp_stats.threads_woken++;
> @@ -657,8 +654,6 @@ int svc_recv(struct svc_rqst *rqstp, long timeout)
> if (xprt) {
> rqstp->rq_xprt = xprt;
> svc_xprt_get(xprt);
> - rqstp->rq_reserved = serv->sv_max_mesg;
> - atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved);
> } else {
> /* No data pending. Go to sleep */
> svc_thread_enqueue(pool, rqstp);
> @@ -741,6 +736,8 @@ int svc_recv(struct svc_rqst *rqstp, long timeout)
> dprintk("svc: server %p, pool %u, transport %p, inuse=%d\n",
> rqstp, pool->sp_id, xprt,
> atomic_read(&xprt->xpt_ref.refcount));
> + rqstp->rq_reserved = serv->sv_max_mesg;
> + atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved);
> rqstp->rq_deferred = svc_deferred_dequeue(xprt);
> if (rqstp->rq_deferred) {
> svc_xprt_received(xprt);
> @@ -1006,6 +1003,8 @@ static struct cache_deferred_req *svc_defer(struct cache_req *req)
> }
> svc_xprt_get(rqstp->rq_xprt);
> dr->xprt = rqstp->rq_xprt;
> + dr->reserved_space = rqstp->rq_reserved;
> + svc_reserve(rqstp, 0);
>
> dr->handle.revisit = svc_revisit;
> return &dr->handle;
> @@ -1018,6 +1017,7 @@ static int svc_deferred_recv(struct svc_rqst *rqstp)
> {
> struct svc_deferred_req *dr = rqstp->rq_deferred;
>
> + svc_reserve(rqstp, dr->reserved_space);
> /* setup iov_base past transport header */
> rqstp->rq_arg.head[0].iov_base = dr->args + (dr->xprt_hlen>>2);
> /* The iov_len does not include the transport header bytes */
>
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