- 15 6月, 2011 1 次提交
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由 Shaohua Li 提交于
Commit a26ac245(rcu: move TREE_RCU from softirq to kthread) introduced performance regression. In an AIM7 test, this commit degraded performance by about 40%. The commit runs rcu callbacks in a kthread instead of softirq. We observed high rate of context switch which is caused by this. Out test system has 64 CPUs and HZ is 1000, so we saw more than 64k context switch per second which is caused by RCU's per-CPU kthread. A trace showed that most of the time the RCU per-CPU kthread doesn't actually handle any callbacks, but instead just does a very small amount of work handling grace periods. This means that RCU's per-CPU kthreads are making the scheduler do quite a bit of work in order to allow a very small amount of RCU-related processing to be done. Alex Shi's analysis determined that this slowdown is due to lock contention within the scheduler. Unfortunately, as Peter Zijlstra points out, the scheduler's real-time semantics require global action, which means that this contention is inherent in real-time scheduling. (Yes, perhaps someone will come up with a workaround -- otherwise, -rt is not going to do well on large SMP systems -- but this patch will work around this issue in the meantime. And "the meantime" might well be forever.) This patch therefore re-introduces softirq processing to RCU, but only for core RCU work. RCU callbacks are still executed in kthread context, so that only a small amount of RCU work runs in softirq context in the common case. This should minimize ksoftirqd execution, allowing us to skip boosting of ksoftirqd for CONFIG_RCU_BOOST=y kernels. Signed-off-by: NShaohua Li <shaohua.li@intel.com> Tested-by: N"Alex,Shi" <alex.shi@intel.com> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
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- 06 5月, 2011 1 次提交
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由 Paul E. McKenney 提交于
If RCU priority boosting is to be meaningful, callback invocation must be boosted in addition to preempted RCU readers. Otherwise, in presence of CPU real-time threads, the grace period ends, but the callbacks don't get invoked. If the callbacks don't get invoked, the associated memory doesn't get freed, so the system is still subject to OOM. But it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit moves the callback invocations to a kthread, which can be boosted easily. Also add comments and properly synchronized all accesses to rcu_cpu_kthread_task, as suggested by Lai Jiangshan. Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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- 21 10月, 2010 1 次提交
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由 Thomas Gleixner 提交于
With the addition of trace_softirq_raise() the softirq tracepoint got even more convoluted. Why the tracepoints take two pointers to assign an integer is beyond my comprehension. But adding an extra case which treats the first pointer as an unsigned long when the second pointer is NULL including the back and forth type casting is just horrible. Convert the softirq tracepoints to take a single unsigned int argument for the softirq vector number and fix the call sites. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> LKML-Reference: <alpine.LFD.2.00.1010191428560.6815@localhost6.localdomain6> Acked-by: NPeter Zijlstra <peterz@infradead.org> Acked-by: mathieu.desnoyers@efficios.com Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org>
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- 07 9月, 2010 1 次提交
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由 Lai Jiangshan 提交于
Add a tracepoint for tracing when softirq action is raised. This and the existing tracepoints complete softirq's tracepoints: softirq_raise, softirq_entry and softirq_exit. And when this tracepoint is used in combination with the softirq_entry tracepoint we can determine the softirq raise latency. Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com> Acked-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: NNeil Horman <nhorman@tuxdriver.com> Cc: David Miller <davem@davemloft.net> Cc: Kaneshige Kenji <kaneshige.kenji@jp.fujitsu.com> Cc: Izumo Taku <izumi.taku@jp.fujitsu.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Scott Mcmillan <scott.a.mcmillan@intel.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> LKML-Reference: <4C724298.4050509@jp.fujitsu.com> [ factorize softirq events with DECLARE_EVENT_CLASS ] Signed-off-by: NKoki Sanagi <sanagi.koki@jp.fujitsu.com> Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
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- 26 11月, 2009 1 次提交
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由 Li Zefan 提交于
Use DECLARE_EVENT_CLASS to remove duplicate code: text data bss dec hex filename 12781 952 36 13769 35c9 kernel/softirq.o.old 11981 952 32 12965 32a5 kernel/softirq.o Two events are converted: softirq: softirq_entry, softirq_exit No change in functionality. Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <4B0E287F.4030708@cn.fujitsu.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 15 10月, 2009 1 次提交
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由 Ingo Molnar 提交于
Now that we can filter based on fields via perf record, people will start using filter expressions and will expect them to be obvious. The primary way to see which fields are available is by looking at the trace output, such as: gcc-18676 [000] 343.011728: irq_handler_entry: irq=0 handler=timer cc1-18677 [000] 343.012727: irq_handler_entry: irq=0 handler=timer cc1-18677 [000] 343.032692: irq_handler_entry: irq=0 handler=timer cc1-18677 [000] 343.033690: irq_handler_entry: irq=0 handler=timer cc1-18677 [000] 343.034687: irq_handler_entry: irq=0 handler=timer cc1-18677 [000] 343.035686: irq_handler_entry: irq=0 handler=timer cc1-18677 [000] 343.036684: irq_handler_entry: irq=0 handler=timer While 'irq==0' filters work, the 'handler==<x>' filter expression does not work: $ perf record -R -f -a -e irq:irq_handler_entry --filter handler=timer sleep 1 Error: failed to set filter with 22 (Invalid argument) The problem is that while an 'irq' field exists and is recognized as a filter field - 'handler' does not exist - its name is 'name' in the output. To solve this, we need to synchronize the printout and the field names, wherever possible. In cases where the printout prints a non-field, we enclose that information in square brackets, such as: perf-1380 [013] 724.903505: softirq_exit: vec=9 [action=RCU] perf-1380 [013] 724.904482: softirq_exit: vec=1 [action=TIMER] This way users can use filter expressions more intuitively: all fields that show up as 'primary' (non-bracketed) information is filterable. This patch harmonizes the field names for all irq, bkl, power, sched and timer events. We might in fact think about dropping the print format bit of generic tracepoints altogether, and just print the fields that are being recorded. Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Tom Zanussi <tzanussi@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> LKML-Reference: <new-submission> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 18 9月, 2009 1 次提交
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由 Li Zefan 提交于
With BLOCK_IOPOLL_SOFTIRQ added, softirq_to_name[] and show_softirq_name() needs to be updated. Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com> LKML-Reference: <4AB20398.8070209@cn.fujitsu.com> Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
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- 13 7月, 2009 1 次提交
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由 Li Zefan 提交于
If TRACE_INCLDUE_FILE is defined, <trace/events/TRACE_INCLUDE_FILE.h> will be included and compiled, otherwise it will be <trace/events/TRACE_SYSTEM.h> So TRACE_SYSTEM should be defined outside of #if proctection, just like TRACE_INCLUDE_FILE. Imaging this scenario: #include <trace/events/foo.h> -> TRACE_SYSTEM == foo ... #include <trace/events/bar.h> -> TRACE_SYSTEM == bar ... #define CREATE_TRACE_POINTS #include <trace/events/foo.h> -> TRACE_SYSTEM == bar !!! and then bar.h will be included and compiled. Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <4A5A9CF1.2010007@cn.fujitsu.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 02 6月, 2009 1 次提交
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由 Steven Rostedt 提交于
After converting the softirq tracer to use te flags options, this caused a regression with the name. Since the flag was used directly it was printed out (i.e. HRTIMER_SOFTIRQ). This patch only shows the softirq name without the SOFTIRQ part. [ Impact: fix regression of output from softirq events ] Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
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- 27 5月, 2009 1 次提交
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由 Steven Rostedt 提交于
The recording of the names at trace time is inefficient. This patch implements the softirq event recording to only record the vector and then use the __print_symbolic interface to print out the names. [ Impact: faster recording of softirq events ] Signed-off-by: NSteven Rostedt <rostedt@goodmis.org> Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
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- 01 5月, 2009 1 次提交
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由 Jason Baron 提交于
Document irqs for the newly created docbook. [ Impact: add documentation ] Signed-off-by: NJason Baron <jbaron@redhat.com> Acked-by: NRandy Dunlap <randy.dunlap@oracle.com> Cc: akpm@linux-foundation.org Cc: rostedt@goodmis.org Cc: fweisbec@gmail.com Cc: mathieu.desnoyers@polymtl.ca Cc: wcohen@redhat.com LKML-Reference: <73ff42be3420157667ec548e9b0e409c3cfad05f.1241107197.git.jbaron@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 24 4月, 2009 1 次提交
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由 Steven Rostedt 提交于
The TRACE_FORMAT will soon be deprecated. This patch converts it to the TRACE_EVENT macro. Note, this change should also speed up the tracing. [ Impact: remove a user of deprecated TRACE_FORMAT ] Cc: Jason Baron <jbaron@redhat.com> Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
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- 15 4月, 2009 2 次提交
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由 Steven Rostedt 提交于
Impact: clean up Create a sub directory in include/trace called events to keep the trace point headers in their own separate directory. Only headers that declare trace points should be defined in this directory. Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Zhao Lei <zhaolei@cn.fujitsu.com> Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
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由 Steven Rostedt 提交于
This patch lowers the number of places a developer must modify to add new tracepoints. The current method to add a new tracepoint into an existing system is to write the trace point macro in the trace header with one of the macros TRACE_EVENT, TRACE_FORMAT or DECLARE_TRACE, then they must add the same named item into the C file with the macro DEFINE_TRACE(name) and then add the trace point. This change cuts out the needing to add the DEFINE_TRACE(name). Every file that uses the tracepoint must still include the trace/<type>.h file, but the one C file must also add a define before the including of that file. #define CREATE_TRACE_POINTS #include <trace/mytrace.h> This will cause the trace/mytrace.h file to also produce the C code necessary to implement the trace point. Note, if more than one trace/<type>.h is used to create the C code it is best to list them all together. #define CREATE_TRACE_POINTS #include <trace/foo.h> #include <trace/bar.h> #include <trace/fido.h> Thanks to Mathieu Desnoyers and Christoph Hellwig for coming up with the cleaner solution of the define above the includes over my first design to have the C code include a "special" header. This patch converts sched, irq and lockdep and skb to use this new method. Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Zhao Lei <zhaolei@cn.fujitsu.com> Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
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- 14 4月, 2009 1 次提交
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由 Steven Rostedt 提交于
Impact: clean up Neil Horman (et. al.) criticized the way the trace events were broken up into two files. The reason for that was that ftrace needed to separate out the declarations from where the #include <linux/tracepoint.h> was used. It then dawned on me that the tracepoint.h header only needs to define the TRACE_EVENT macro if it is not already defined. The solution is simply to test if TRACE_EVENT is defined, and if it is not then the linux/tracepoint.h header can define it. This change consolidates all the <traces>.h and <traces>_event_types.h into the <traces>.h file. Reported-by: NNeil Horman <nhorman@tuxdriver.com> Reported-by: NTheodore Tso <tytso@mit.edu> Reported-by: NJiaying Zhang <jiayingz@google.com> Cc: Zhaolei <zhaolei@cn.fujitsu.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jason Baron <jbaron@redhat.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
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- 27 2月, 2009 1 次提交
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由 Jason Baron 提交于
Impact: add new tracepoints Add them to the generic IRQ code, that way every architecture gets these new tracepoints, not just x86. Using Steve's new 'TRACE_FORMAT', I can get function graph trace as follows using the original two IRQ tracepoints: 3) | handle_IRQ_event() { 3) | /* (irq_handler_entry) irq=28 handler=eth0 */ 3) | e1000_intr_msi() { 3) 2.460 us | __napi_schedule(); 3) 9.416 us | } 3) | /* (irq_handler_exit) irq=28 handler=eth0 return=handled */ 3) + 22.935 us | } Signed-off-by: NJason Baron <jbaron@redhat.com> Signed-off-by: NSteven Rostedt <rostedt@goodmis.org> Acked-by: NPeter Zijlstra <peterz@infradead.org> Acked-by: NMasami Hiramatsu <mhiramat@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org> Cc: "Frank Ch. Eigler" <fche@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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