lkml.org 
[lkml]   [2020]   [Apr]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] 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.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
kernel/trace/Kconfig | 9 ---------
1 file changed, 9 deletions(-)

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 402eef84c859..568ad371e19c 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
\
 
 \ /
  Last update: 2020-04-09 12:41    [W:0.308 / U:0.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site