user/sven/linux.git/kernel/trace/trace_hwlat.c, branch v5.4.68

tracing/hwlat: Honor the tracing_cpumask

2020-08-21T11:05:27Z

commit 96b4833b6827a62c295b149213c68b559514c929 upstream. In calculation of the cpu mask for the hwlat kernel thread, the wrong cpu mask is used instead of the tracing_cpumask, this causes the tracing/tracing_cpumask useless for hwlat tracer. Fixes it. Link: https://lkml.kernel.org/r/20200730082318.42584-2-haokexin@gmail.com Cc: Ingo Molnar Cc: stable@vger.kernel.org Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs") Signed-off-by: Kevin Hao Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman

tracing/hwlat: Don't ignore outer-loop duration when calculating max_latency

2019-10-13T00:49:33Z

max_latency is intended to record the maximum ever observed hardware latency, which may occur in either part of the loop (inner/outer). So we need to also consider the outer-loop sample when updating max_latency. Link: http://lkml.kernel.org/r/157073345463.17189.18124025522664682811.stgit@srivatsa-ubuntu Fixes: e7c15cd8a113 ("tracing: Added hardware latency tracer") Cc: stable@vger.kernel.org Signed-off-by: Srivatsa S. Bhat (VMware) Signed-off-by: Steven Rostedt (VMware)

tracing/hwlat: Report total time spent in all NMIs during the sample

2019-10-13T00:49:33Z

nmi_total_ts is supposed to record the total time spent in *all* NMIs that occur on the given CPU during the (active portion of the) sampling window. However, the code seems to be overwriting this variable for each NMI, thereby only recording the time spent in the most recent NMI. Fix it by accumulating the duration instead. Link: http://lkml.kernel.org/r/157073343544.17189.13911783866738671133.stgit@srivatsa-ubuntu Fixes: 7b2c86250122 ("tracing: Add NMI tracing in hwlat detector") Cc: stable@vger.kernel.org Signed-off-by: Srivatsa S. Bhat (VMware) Signed-off-by: Steven Rostedt (VMware)

sched/core: Provide a pointer to the valid CPU mask

2019-06-03T09:49:37Z

In commit: 4b53a3412d66 ("sched/core: Remove the tsk_nr_cpus_allowed() wrapper") the tsk_nr_cpus_allowed() wrapper was removed. There was not much difference in !RT but in RT we used this to implement migrate_disable(). Within a migrate_disable() section the CPU mask is restricted to single CPU while the "normal" CPU mask remains untouched. As an alternative implementation Ingo suggested to use: struct task_struct { const cpumask_t *cpus_ptr; cpumask_t cpus_mask; }; with t->cpus_ptr = &t->cpus_mask; In -RT we then can switch the cpus_ptr to: t->cpus_ptr = &cpumask_of(task_cpu(p)); in a migration disabled region. The rules are simple: - Code that 'uses' ->cpus_allowed would use the pointer. - Code that 'modifies' ->cpus_allowed would use the direct mask. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Thomas Gleixner Cc: Linus Torvalds Cc: Peter Zijlstra Link: https://lkml.kernel.org/r/20190423142636.14347-1-bigeasy@linutronix.de Signed-off-by: Ingo Molnar

tracing: Add SPDX License format tags to tracing files

2018-08-16T23:08:06Z

Add the SPDX License header to ease license compliance management. Signed-off-by: Steven Rostedt (VMware)

tracing: Do a WARN_ON() if start_thread() in hwlat is called when thread exists

2018-08-01T20:06:02Z

The start function of the hwlat tracer should never be called when the hwlat thread already exists. If it is called, do a WARN_ON(). Signed-off-by: Steven Rostedt (VMware)

ftrace: Add missing check for existing hwlat thread

2018-08-01T20:04:24Z

The hwlat tracer uses a kernel thread to measure latencies. The function that creates this kernel thread, start_kthread(), can be called when the tracer is initialized and when the tracer is explicitly enabled. start_kthread() does not check if there is an existing hwlat kernel thread and will create a new one each time it is called. This causes the reference to the previous thread to be lost. Without the thread reference, the old kernel thread becomes unstoppable and continues to use CPU time even after the hwlat tracer has been disabled. This problem can be observed when a system is booted with tracing enabled and the hwlat tracer is configured like this: echo hwlat > current_tracer; echo 1 > tracing_on Add the missing check for an existing kernel thread in start_kthread() to prevent this problem. This function and the rest of the hwlat kernel thread setup and teardown are already serialized because they are called through the tracer core code with trace_type_lock held. [ Note, this only fixes the symptom. The real fix was not to call this function when tracing_on was already one. But this still makes the code more robust, so we'll add it. ] Link: http://lkml.kernel.org/r/1533120354-22923-1-git-send-email-erica.bugden@linutronix.de Signed-off-by: Erica Bugden Signed-off-by: Steven Rostedt (VMware)

trace: make trace_hwlat timestamp y2038 safe

2017-05-09T00:15:15Z

struct timespec is not y2038 safe on 32 bit machines and needs to be replaced by struct timespec64 in order to represent times beyond year 2038 on such machines. Fix all the timestamp representation in struct trace_hwlat and all the corresponding implementations. Link: http://lkml.kernel.org/r/1491613030-11599-3-git-send-email-deepa.kernel@gmail.com Signed-off-by: Deepa Dinamani Acked-by: Steven Rostedt (VMware) Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:27Z

We are going to split out of , which will have to be picked up from other headers and .c files. Create a trivial placeholder file that just maps to to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

Merge tag 'trace-v4.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2017-02-27T21:36:19Z

Pull another tracing update from Steven Rostedt: "Commit 79c6f448c8b79c ("tracing: Fix hwlat kthread migration") fixed a bug that was caused by a race condition in initializing the hwlat thread. When fixing this code, I realized that it should have been done differently. Instead of doing the rewrite and sending that to stable, I just sent the above commit to fix the bug that should be back ported. This commit is on top of the quick fix commit to rewrite the code the way it should have been written in the first place" * tag 'trace-v4.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Clean up the hwlat binding code