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trace,smp: Add tracepoints around remotelly called functions

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The recently added ipi_send_{cpu,cpumask} tracepoints allow finding sources
of IPIs targeting CPUs running latency-sensitive applications.

For NOHZ_FULL CPUs, all IPIs are interference, and those tracepoints are
sufficient to find them and work on getting rid of them. In some setups
however, not *all* IPIs are to be suppressed, but long-running IPI
callbacks can still be problematic.

Add a pair of tracepoints to mark the start and end of processing a CSD IPI
callback, similar to what exists for softirq, workqueue or timer callbacks.

Signed-off-by: Leonardo Bras <leobras@redhat.com>
Tested-and-reviewed-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230615065944.188876-5-leobras@redhat.com
This commit is contained in:
Leonardo Bras
2023-06-15 03:59:45 -03:00
committed by Peter Zijlstra
parent 60be49bdf1
commit 949fa3f11c
2 changed files with 64 additions and 6 deletions
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45
include/trace/events/csd.h Normal file
View File

@@ -0,0 +1,45 @@
/* SPDX-License-Identifier: GPL-2.0 */
#undef TRACE_SYSTEM
#define TRACE_SYSTEM csd
#if !defined(_TRACE_CSD_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_CSD_H
#include <linux/tracepoint.h>
/*
* Tracepoints for a function which is called as an effect of smp_call_function.*
*/
DECLARE_EVENT_CLASS(csd_function,
TP_PROTO(smp_call_func_t func, struct __call_single_data *csd),
TP_ARGS(func, csd),
TP_STRUCT__entry(
__field(void *, func)
__field(void *, csd)
),
TP_fast_assign(
__entry->func = func;
__entry->csd = csd;
),
TP_printk("func=%ps, csd=%p", __entry->func, __entry->csd)
);
DEFINE_EVENT(csd_function, csd_function_entry,
TP_PROTO(smp_call_func_t func, struct __call_single_data *csd),
TP_ARGS(func, csd)
);
DEFINE_EVENT(csd_function, csd_function_exit,
TP_PROTO(smp_call_func_t func, struct __call_single_data *csd),
TP_ARGS(func, csd)
);
#endif /* _TRACE_CSD_H */
/* This part must be outside protection */
#include <trace/define_trace.h>