> On Nov 23, 2015, at 7:39 PM, Tom Talpey <[email protected]> wrote: > > On 11/23/2015 5:20 PM, Chuck Lever wrote: >> Extra resources for handling backchannel requests have to be >> pre-allocated when a transport instance is created. Set a limit. >> >> Signed-off-by: Chuck Lever <[email protected]> >> --- >> include/linux/sunrpc/svc_rdma.h | 5 +++++ >> net/sunrpc/xprtrdma/svc_rdma_transport.c | 6 +++++- >> 2 files changed, 10 insertions(+), 1 deletion(-) >> >> diff --git a/include/linux/sunrpc/svc_rdma.h >> b/include/linux/sunrpc/svc_rdma.h >> index f869807..478aa30 100644 >> --- a/include/linux/sunrpc/svc_rdma.h >> +++ b/include/linux/sunrpc/svc_rdma.h >> @@ -178,6 +178,11 @@ struct svcxprt_rdma { >> #define RPCRDMA_SQ_DEPTH_MULT 8 >> #define RPCRDMA_MAX_REQUESTS 32 >> #define RPCRDMA_MAX_REQ_SIZE 4096 >> +#if defined(CONFIG_SUNRPC_BACKCHANNEL) > > Why is this a config option? Why wouldn't you always want > this? It's needed for any post-1990 NFS dialect.
I think some distros want to be able to compile out NFSv4.x on small systems, and take all the backchannel cruft with it. >> +#define RPCRDMA_MAX_BC_REQUESTS 8 > > Why a constant 8? The forward channel value is apparently > configurable, just a few lines down. The client side backward direction credit limit, now in 4.4, is already a constant. The client side ULP uses a constant for the slot table size: NFS4_MAX_BACK_CHANNEL_OPS. I’m not 100% sure but the server seems to just echo that number back to the client. I’d rather not add an admin knob for this. Why would it be necessary? >> +#else >> +#define RPCRDMA_MAX_BC_REQUESTS 0 >> +#endif >> >> #define RPCSVC_MAXPAYLOAD_RDMA RPCSVC_MAXPAYLOAD >> >> diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c >> b/net/sunrpc/xprtrdma/svc_rdma_transport.c >> index b348b4a..01c7b36 100644 >> --- a/net/sunrpc/xprtrdma/svc_rdma_transport.c >> +++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c >> @@ -923,8 +923,10 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt >> *xprt) >> (size_t)RPCSVC_MAXPAGES); >> newxprt->sc_max_sge_rd = min_t(size_t, devattr.max_sge_rd, >> RPCSVC_MAXPAGES); >> + /* XXX: what if HCA can't support enough WRs for bc operation? */ >> newxprt->sc_max_requests = min((size_t)devattr.max_qp_wr, >> - (size_t)svcrdma_max_requests); >> + (size_t)(svcrdma_max_requests + >> + RPCRDMA_MAX_BC_REQUESTS)); >> newxprt->sc_sq_depth = RPCRDMA_SQ_DEPTH_MULT * newxprt->sc_max_requests; >> >> /* >> @@ -964,7 +966,9 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt >> *xprt) >> qp_attr.event_handler = qp_event_handler; >> qp_attr.qp_context = &newxprt->sc_xprt; >> qp_attr.cap.max_send_wr = newxprt->sc_sq_depth; >> + qp_attr.cap.max_send_wr += RPCRDMA_MAX_BC_REQUESTS; >> qp_attr.cap.max_recv_wr = newxprt->sc_max_requests; >> + qp_attr.cap.max_recv_wr += RPCRDMA_MAX_BC_REQUESTS; >> qp_attr.cap.max_send_sge = newxprt->sc_max_sge; >> qp_attr.cap.max_recv_sge = newxprt->sc_max_sge; >> qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR; >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >> the body of a message to [email protected] >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Chuck Lever -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
