git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
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Head SHA1: 388d8bdb87e01bcea6d0b2bf797b5f6d7b2401fb
Mel Gorman (1):
tracing: Remove obsolete PREEMPTIRQ_EVENTS kconfig option
----
kernel/trace/Kconfig | 9 ---------
1 file changed, 9 deletions(-)
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commit 388d8bdb87e01bcea6d0b2bf797b5f6d7b2401fb
Author: Mel Gorman <[email protected]>
Date: Thu Apr 9 11:40:34 2020 +0100
tracing: Remove obsolete PREEMPTIRQ_EVENTS kconfig option
The PREEMPTIRQ_EVENTS option is unused after commit c3bc8fd637a9 ("tracing:
Centralize preemptirq tracepoints and unify their usage"). Remove it.
Note that this option is hazardous as it stands. It enables TRACE_IRQFLAGS
event on non-preempt configurations without the irqsoff tracer enabled.
TRACE_IRQFLAGS as it stands incurs significant overhead on each IRQ
entry/exit. This is because trace_hardirqs_[on|off] does all the per-cpu
manipulations and NMI checks even if tracing is completely disabled for
some insane reason. For example, netperf running UDP_STREAM on localhost
incurs a 4-6% performance penalty without any tracing if IRQFLAGS is
set. It can be put behind a static brach but even the function entry/exit
costs a little bit.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mel Gorman <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 75407d5dc83a..0c82ac2c5688 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -258,15 +258,6 @@ config TRACE_PREEMPT_TOGGLE
Enables hooks which will be called when preemption is first disabled,
and last enabled.
-config PREEMPTIRQ_EVENTS
- bool "Enable trace events for preempt and irq disable/enable"
- select TRACE_IRQFLAGS
- select TRACE_PREEMPT_TOGGLE if PREEMPTION
- select GENERIC_TRACER
- default n
- help
- Enable tracing of disable and enable events for preemption and irqs.
-
config IRQSOFF_TRACER
bool "Interrupts-off Latency Tracer"
default n
