RE: [PATCH RFC] IB/core: Trace points for diagnosing completion queue issues

[Parav Pandit <parav@mellanox.com>]

Hi Chuck,

> -----Original Message-----
> From: linux-rdma-owner@vger.kernel.org <linux-rdma-
> owner@vger.kernel.org> On Behalf Of Chuck Lever
> Sent: Friday, October 4, 2019 8:57 AM
> To: linux-rdma@vger.kernel.org
> Subject: [PATCH RFC] IB/core: Trace points for diagnosing completion queue
> issues
> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  drivers/infiniband/core/Makefile |    2
>  drivers/infiniband/core/cq.c     |   29 ++++--
>  drivers/infiniband/core/trace.c  |   15 +++
>  include/rdma/ib_verbs.h          |    2
>  include/trace/events/rdma.h      |   89 ++++++++++++++++++
>  include/trace/events/rdma_core.h |  192
> ++++++++++++++++++++++++++++++++++++++
>  6 files changed, 319 insertions(+), 10 deletions(-)  create mode 100644
> drivers/infiniband/core/trace.c  create mode 100644
> include/trace/events/rdma_core.h
> 
> diff --git a/drivers/infiniband/core/Makefile b/drivers/infiniband/core/Makefile
> index 09881bd..68d9e27 100644
> --- a/drivers/infiniband/core/Makefile
> +++ b/drivers/infiniband/core/Makefile
> @@ -11,7 +11,7 @@ ib_core-y :=			packer.o ud_header.o
> verbs.o cq.o rw.o sysfs.o \
>  				device.o fmr_pool.o cache.o netlink.o \
>  				roce_gid_mgmt.o mr_pool.o addr.o
> sa_query.o \
>  				multicast.o mad.o smi.o agent.o mad_rmpp.o \
> -				nldev.o restrack.o counters.o
> +				nldev.o restrack.o counters.o trace.o
> 
>  ib_core-$(CONFIG_SECURITY_INFINIBAND) += security.o
>  ib_core-$(CONFIG_CGROUP_RDMA) += cgroup.o diff --git
> a/drivers/infiniband/core/cq.c b/drivers/infiniband/core/cq.c index
> bbfded6..bcde992 100644
> --- a/drivers/infiniband/core/cq.c
> +++ b/drivers/infiniband/core/cq.c
> @@ -7,6 +7,8 @@
>  #include <linux/slab.h>
>  #include <rdma/ib_verbs.h>
> 
> +#include <trace/events/rdma_core.h>
> +
>  /* # of WCs to poll for with a single call to ib_poll_cq */
>  #define IB_POLL_BATCH			16
>  #define IB_POLL_BATCH_DIRECT		8
> @@ -41,6 +43,7 @@ static void ib_cq_rdma_dim_work(struct work_struct *w)
> 
>  	dim->state = DIM_START_MEASURE;
> 
> +	trace_cq_modify(cq, comps, usec);
>  	cq->device->ops.modify_cq(cq, comps, usec);  }
> 
> @@ -70,13 +73,9 @@ static int __ib_process_cq(struct ib_cq *cq, int budget,
> struct ib_wc *wcs,  {
>  	int i, n, completed = 0;
> 
> -	/*
> -	 * budget might be (-1) if the caller does not
> -	 * want to bound this call, thus we need unsigned
> -	 * minimum here.
> -	 */
> -	while ((n = ib_poll_cq(cq, min_t(u32, batch,
> -					 budget - completed), wcs)) > 0) {
> +	trace_cq_process(cq);
> +	while ((n = ib_poll_cq(cq, batch, wcs)) > 0) {
> +		trace_cq_poll(cq, batch, n);
>  		for (i = 0; i < n; i++) {
>  			struct ib_wc *wc = &wcs[i];
> 
> @@ -87,9 +86,15 @@ static int __ib_process_cq(struct ib_cq *cq, int budget,
> struct ib_wc *wcs,
>  		}
> 
>  		completed += n;
> -
>  		if (n != batch || (budget != -1 && completed >= budget))
>  			break;
> +
> +		/*
> +		 * budget might be (-1) if the caller does not
> +		 * want to bound this call, thus we need unsigned
> +		 * minimum here.
> +		 */
> +		batch = min_t(u32, batch, budget - completed);
>  	}
> 
>  	return completed;
> @@ -131,8 +136,10 @@ static int ib_poll_handler(struct irq_poll *iop, int
> budget)
>  	completed = __ib_process_cq(cq, budget, cq->wc, IB_POLL_BATCH);
>  	if (completed < budget) {
>  		irq_poll_complete(&cq->iop);
> -		if (ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
> +		if (ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0) {
> +			trace_cq_reschedule(cq);
>  			irq_poll_sched(&cq->iop);
> +		}
>  	}
> 
>  	if (dim)
> @@ -143,6 +150,7 @@ static int ib_poll_handler(struct irq_poll *iop, int
> budget)
> 
>  static void ib_cq_completion_softirq(struct ib_cq *cq, void *private)  {
> +	trace_cq_schedule(cq);
>  	irq_poll_sched(&cq->iop);
>  }
> 
> @@ -162,6 +170,7 @@ static void ib_cq_poll_work(struct work_struct *work)
> 
>  static void ib_cq_completion_workqueue(struct ib_cq *cq, void *private)  {
> +	trace_cq_schedule(cq);
>  	queue_work(cq->comp_wq, &cq->work);
>  }
> 
> @@ -239,6 +248,7 @@ struct ib_cq *__ib_alloc_cq_user(struct ib_device *dev,
> void *private,
>  		goto out_destroy_cq;
>  	}
> 
> +	trace_cq_alloc(cq, comp_vector, poll_ctx);
>  	return cq;
> 
>  out_destroy_cq:
> @@ -304,6 +314,7 @@ void ib_free_cq_user(struct ib_cq *cq, struct ib_udata
> *udata)
>  		WARN_ON_ONCE(1);
>  	}
> 
> +	trace_cq_free(cq);
>  	rdma_restrack_del(&cq->res);
>  	cq->device->ops.destroy_cq(cq, udata);
>  	if (cq->dim)
> diff --git a/drivers/infiniband/core/trace.c b/drivers/infiniband/core/trace.c
> new file mode 100644 index 0000000..568f57d
> --- /dev/null
> +++ b/drivers/infiniband/core/trace.c
> @@ -0,0 +1,15 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Trace points for core RDMA functions.
> + *
> + * Author: Chuck Lever <chuck.lever@oracle.com>
> + *
> + * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
> + */
> +
> +#define CREATE_TRACE_POINTS
> +
> +#include <rdma/ib_verbs.h>
> +#include <rdma/rdma_cm.h>
> +
I think rdma_cm.h inclusion is not needed here?

> +#include <trace/events/rdma_core.h>
> diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h index
> 6a47ba8..95a6bce 100644
> --- a/include/rdma/ib_verbs.h
> +++ b/include/rdma/ib_verbs.h
> @@ -1555,6 +1555,8 @@ struct ib_cq {
>  	};
>  	struct workqueue_struct *comp_wq;
>  	struct dim *dim;
> +	ktime_t timestamp;
> +	bool interrupt;
>  	/*
>  	 * Implementation details of the RDMA core, don't use in drivers:
>  	 */
> diff --git a/include/trace/events/rdma.h b/include/trace/events/rdma.h index
> aa19afc..d5e5fa7a 100644
> --- a/include/trace/events/rdma.h
> +++ b/include/trace/events/rdma.h
> @@ -127,3 +127,92 @@
> 
>  #define rdma_show_cm_event(x) \
>  		__print_symbolic(x, RDMA_CM_EVENT_LIST)
> +
> +/*
> + * enum ib_poll_context, from include/rdma/ib_verbs.h  */
> +#define IB_POLL_CTX_LIST			\
> +	ib_poll_ctx(DIRECT)			\
> +	ib_poll_ctx(SOFTIRQ)			\
> +	ib_poll_ctx(WORKQUEUE)			\
> +	ib_poll_ctx_end(UNBOUND_WORKQUEUE)
> +
> +#undef ib_poll_ctx
> +#undef ib_poll_ctx_end
> +
> +#define ib_poll_ctx(x)		TRACE_DEFINE_ENUM(IB_POLL_##x);
> +#define ib_poll_ctx_end(x)	TRACE_DEFINE_ENUM(IB_POLL_##x);
> +
> +IB_POLL_CTX_LIST
> +
> +#undef ib_poll_ctx
> +#undef ib_poll_ctx_end
> +
> +#define ib_poll_ctx(x)		{ IB_POLL_##x, #x },
> +#define ib_poll_ctx_end(x)	{ IB_POLL_##x, #x }
> +
> +#define rdma_show_ib_poll_ctx(x) \
> +		__print_symbolic(x, IB_POLL_CTX_LIST)
> +
> +/*
> + * enum ib_wc_opcode, from include/rdma/ib_verbs.h  */
> +#define IB_WC_OPCODE_LIST			\
> +	ib_wc_opcode(SEND)			\
> +	ib_wc_opcode(RDMA_WRITE)		\
> +	ib_wc_opcode(RDMA_READ)			\
> +	ib_wc_opcode(COMP_SWAP)			\
> +	ib_wc_opcode(FETCH_ADD)			\
> +	ib_wc_opcode(LSO)			\
> +	ib_wc_opcode(LOCAL_INV)			\
> +	ib_wc_opcode(REG_MR)			\
> +	ib_wc_opcode(MASKED_COMP_SWAP)		\
> +	ib_wc_opcode(MASKED_FETCH_ADD)		\
> +	ib_wc_opcode(RECV)			\
> +	ib_wc_opcode_end(RECV_RDMA_WITH_IMM)
> +
> +#undef ib_wc_opcode
> +#undef ib_wc_opcode_end
> +
> +#define ib_wc_opcode(x)		TRACE_DEFINE_ENUM(IB_WC_##x);
> +#define ib_wc_opcode_end(x)	TRACE_DEFINE_ENUM(IB_WC_##x);
> +
> +IB_WC_OPCODE_LIST
> +
> +#undef ib_wc_opcode
> +#undef ib_wc_opcode_end
> +
> +#define ib_wc_opcode(x)		{ IB_WC_##x, #x },
> +#define ib_wc_opcode_end(x)	{ IB_WC_##x, #x }
> +
> +#define rdma_show_wc_opcode(x) \
> +		__print_symbolic(x, IB_WC_OPCODE_LIST)
> +
> +/*
> + * enum ib_wc_flags, from include/rdma/ib_verbs.h  */
> +#define IB_WC_FLAGS_LIST			\
> +	ib_wc_flags(GRH)			\
> +	ib_wc_flags(WITH_IMM)			\
> +	ib_wc_flags(WITH_INVALIDATE)		\
> +	ib_wc_flags(IP_CSUM_OK)			\
> +	ib_wc_flags(WITH_SMAC)			\
> +	ib_wc_flags(WITH_VLAN)			\
> +	ib_wc_flags_end(WITH_NETWORK_HDR_TYPE)
> +
> +#undef ib_wc_flags
> +#undef ib_wc_flags_end
> +
> +#define ib_wc_flags(x)		TRACE_DEFINE_ENUM(IB_WC_##x);
> +#define ib_wc_flags_end(x)	TRACE_DEFINE_ENUM(IB_WC_##x);
> +
> +IB_WC_FLAGS_LIST
> +
> +#undef ib_wc_flags
> +#undef ib_wc_flags_end
> +
> +#define ib_wc_flags(x)		{ IB_WC_##x, #x },
> +#define ib_wc_flags_end(x)	{ IB_WC_##x, #x }
> +
> +#define rdma_show_wc_flags(x) \
> +		__print_symbolic(x, IB_WC_FLAGS_LIST)
> diff --git a/include/trace/events/rdma_core.h
> b/include/trace/events/rdma_core.h
> new file mode 100644
> index 0000000..d5cafe8
> --- /dev/null
> +++ b/include/trace/events/rdma_core.h
> @@ -0,0 +1,192 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Trace point definitions for core RDMA functions.
> + *
> + * Author: Chuck Lever <chuck.lever@oracle.com>
> + *
> + * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
> + */
> +
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM rdma_core
> +
> +#if !defined(_TRACE_RDMA_CORE_H) ||
> defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_RDMA_CORE_H
> +
> +#include <linux/tracepoint.h>
> +#include <trace/events/rdma.h>
> +#include <rdma/ib_verbs.h>
> +
> +/**
> + ** Completion Queue events
> + **/
> +
> +TRACE_EVENT(cq_schedule,
> +	TP_PROTO(
> +		struct ib_cq *cq
> +	),
> +
> +	TP_ARGS(cq),
> +
> +	TP_STRUCT__entry(
> +		__field(const void *, cq)
> +	),
> +
> +	TP_fast_assign(
> +		cq->timestamp = ktime_get();
> +		cq->interrupt = true;
> +
> +		__entry->cq = cq;
> +	),
> +
> +	TP_printk("cq=%p", __entry->cq)
> +);
Instead of printing kernel address, cq->res.id should be better.

> +
> +TRACE_EVENT(cq_reschedule,
> +	TP_PROTO(
> +		struct ib_cq *cq
> +	),
> +
> +	TP_ARGS(cq),
> +
> +	TP_STRUCT__entry(
> +		__field(const void *, cq)
> +	),
> +
> +	TP_fast_assign(
> +		cq->timestamp = ktime_get();
> +		cq->interrupt = false;
> +
> +		__entry->cq = cq;
> +	),
> +
> +	TP_printk("cq=%p", __entry->cq)
cq->res.id and for few more places below.

> +);
> +
> +TRACE_EVENT(cq_process,
> +	TP_PROTO(
> +		const struct ib_cq *cq
> +	),
> +
> +	TP_ARGS(cq),
> +
> +	TP_STRUCT__entry(
> +		__field(const void *, cq)
> +		__field(s64, latency)
> +		__field(bool, interrupt)
> +	),
> +
> +	TP_fast_assign(
> +		ktime_t latency = ktime_sub(ktime_get(), cq->timestamp);
> +
> +		__entry->cq = cq;
> +		__entry->latency = ktime_to_us(latency);
> +		__entry->interrupt = cq->interrupt;
> +	),
> +
> +	TP_printk("cq=%p: wake-up took %lld [us] from %s",
> +		__entry->cq, __entry->latency,
> +		__entry->interrupt ? "interrupt" : "reschedule"
> +	)
> +);
> +
> +TRACE_EVENT(cq_poll,
> +	TP_PROTO(
> +		const struct ib_cq *cq,
> +		int requested,
> +		int rc
> +	),
> +
> +	TP_ARGS(cq, requested, rc),
> +
> +	TP_STRUCT__entry(
> +		__field(const void *, cq)
> +		__field(int, requested)
> +		__field(int, rc)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->cq = cq;
> +		__entry->requested = requested;
> +		__entry->rc = rc;
> +	),
> +
> +	TP_printk("cq=%p: requested %d, returned %d",
> +		__entry->cq, __entry->requested, __entry->rc
> +	)
> +);
> +
> +TRACE_EVENT(cq_modify,
> +	TP_PROTO(
> +		const struct ib_cq *cq,
> +		u16 comps,
> +		u16 usec
> +	),
> +
> +	TP_ARGS(cq, comps, usec),
> +
> +	TP_STRUCT__entry(
> +		__field(const void *, cq)
> +		__field(unsigned int, comps)
> +		__field(unsigned int, usec)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->cq = cq;
> +		__entry->comps = comps;
> +		__entry->usec = usec;
> +	),
> +
> +	TP_printk("cq=%p: comps=%u usec=%u",
> +		__entry->cq, __entry->comps, __entry->usec
> +	)
> +);
> +
> +TRACE_EVENT(cq_alloc,
> +	TP_PROTO(
> +		const struct ib_cq *cq,
> +		int comp_vector,
> +		enum ib_poll_context poll_ctx
> +	),
> +
> +	TP_ARGS(cq, comp_vector, poll_ctx),
> +
> +	TP_STRUCT__entry(
> +		__field(const void *, cq)
> +		__field(int, comp_vector)
> +		__field(unsigned long, poll_ctx)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->cq = cq;
> +		__entry->comp_vector = comp_vector;
> +		__entry->poll_ctx = poll_ctx;
> +	),
> +
> +	TP_printk("cq=%p: comp_vector=%d poll_ctx=%s",
> +		__entry->cq, __entry->comp_vector,
> +		rdma_show_ib_poll_ctx(__entry->poll_ctx)
> +	)
> +);
> +
> +TRACE_EVENT(cq_free,
> +	TP_PROTO(
> +		const struct ib_cq *cq
> +	),
> +
> +	TP_ARGS(cq),
> +
> +	TP_STRUCT__entry(
> +		__field(const void *, cq)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->cq = cq;
> +	),
> +
> +	TP_printk("cq=%p", __entry->cq)
> +);
> +
> +#endif /* _TRACE_RDMA_CORE_H */
> +
> +#include <trace/define_trace.h>