On Fri, 18 Oct 2019 17:02:24 +0300
Georgi Djakov <georgi.djakov@xxxxxxxxxx> wrote:
> The tracepoints can help with understanding the system behavior of a
> given interconnect path when the consumer drivers change their bandwidth
> demands. This might be interesting when we want to monitor the requested
> interconnect bandwidth for each client driver. The paths may share the
> same nodes and this will help to understand "who and when is requesting
> what". All this is useful for subsystem drivers developers and may also
> provide hints when optimizing the power and performance profile of the
> system.
>
> Signed-off-by: Georgi Djakov <georgi.djakov@xxxxxxxxxx>
> ---
> MAINTAINERS | 1 +
> drivers/interconnect/core.c | 9 +++++
> include/trace/events/interconnect.h | 52 +++++++++++++++++++++++++++++
> 3 files changed, 62 insertions(+)
> create mode 100644 include/trace/events/interconnect.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 55199ef7fa74..c307c4b8f677 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8526,6 +8526,7 @@ F: drivers/interconnect/
> F: include/dt-bindings/interconnect/
> F: include/linux/interconnect-provider.h
> F: include/linux/interconnect.h
> +F: include/trace/events/interconnect.h
>
> INVENSENSE MPU-3050 GYROSCOPE DRIVER
> M: Linus Walleij <linus.walleij@xxxxxxxxxx>
> diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
> index 7b971228df38..e24092558c29 100644
> --- a/drivers/interconnect/core.c
> +++ b/drivers/interconnect/core.c
> @@ -24,6 +24,9 @@ static LIST_HEAD(icc_providers);
> static DEFINE_MUTEX(icc_lock);
> static struct dentry *icc_debugfs_dir;
>
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/interconnect.h>
> +
> /**
> * struct icc_req - constraints that are attached to each node
> * @req_node: entry in list of requests for the particular @node
> @@ -449,6 +452,9 @@ int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
>
> /* aggregate requests for this node */
> aggregate_requests(node);
> +
> + trace_icc_set_bw(node, dev_name(path->reqs[i].dev),
> + avg_bw, peak_bw);
BTW, it's best to do the "dev_name()" from the TP_fast_assign()
portion. It keeps the work out of the inlined code here. Although it
shouldn't be processed within the fast path, it still adds a cache
footprint.
trace_icc_set_bw(node, path->reqs[i].dev, avg_bw, peak_bw);
> }
>
> ret = apply_constraints(path);
> @@ -461,6 +467,9 @@ int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
> path->reqs[i].avg_bw = old_avg;
> path->reqs[i].peak_bw = old_peak;
> aggregate_requests(node);
> +
> + trace_icc_set_bw(node, dev_name(path->reqs[i].dev),
> + old_avg, old_peak);
> }
> apply_constraints(path);
> }
> diff --git a/include/trace/events/interconnect.h b/include/trace/events/interconnect.h
> new file mode 100644
> index 000000000000..8e001382e9b0
> --- /dev/null
> +++ b/include/trace/events/interconnect.h
> @@ -0,0 +1,52 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2019, Linaro Ltd.
> + * Author: Georgi Djakov <georgi.djakov@xxxxxxxxxx>
> + */
> +
> +#if !defined(_TRACE_INTERCONNECT_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_INTERCONNECT_H
> +
> +#include <linux/tracepoint.h>
> +
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM interconnect
> +
> +struct icc_node;
> +
> +TRACE_EVENT(icc_set_bw,
> +
> + TP_PROTO(struct icc_node *n, const char *cdev, u32 avg_bw, u32 peak_bw),
TP_PROTO(struct icc_node *n, const struct device *cdev,
> +
> + TP_ARGS(n, cdev, avg_bw, peak_bw),
> +
> + TP_STRUCT__entry(
> + __string(node_name, n->name)
> + __field(u32, node_avg_bw)
> + __field(u32, node_peak_bw)
> + __string(cdev, cdev)
__string(cdev, dev_name(cdev))
> + __field(u32, avg_bw)
> + __field(u32, peak_bw)
> + ),
> +
> + TP_fast_assign(
> + __assign_str(node_name, n->name);
> + __entry->node_avg_bw = n->avg_bw;
> + __entry->node_peak_bw = n->peak_bw;
> + __assign_str(cdev, cdev);
__assign_str(cdev, dev_name(cdev));
-- Steve
> + __entry->avg_bw = avg_bw;
> + __entry->peak_bw = peak_bw;
> + ),
> +
> + TP_printk("%s avg_bw=%u peak_bw=%u cdev=%s avg_bw=%u peak_bw=%u",
> + __get_str(node_name),
> + __entry->node_avg_bw,
> + __entry->node_peak_bw,
> + __get_str(cdev),
> + __entry->avg_bw,
> + __entry->peak_bw)
> +);
> +#endif /* _TRACE_INTERCONNECT_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
