linux/kernel/events/core.c, branch v3.4-rc2

Merge branch 'linus' into perf/urgent

2012-03-26T15:19:03Z

Merge reason: we need to fix a non-trivial merge conflict. Signed-off-by: Ingo Molnar

perf: Move mmap page data_head offset assertion out of header

2012-03-24T07:46:59Z

Having the build time assertion in header is making the perf build fail on x86 with: ../../include/linux/perf_event.h:411:32: error: variably modified \ ‘__assert_mmap_data_head_offset’ at file scope [-Werror] I'm moving the build time validation out of the header, because I think it's better than to lessen the perf build warn/error check. Signed-off-by: Jiri Olsa Cc: acme@redhat.com Cc: a.p.zijlstra@chello.nl Cc: paulus@samba.org Cc: cjashfor@linux.vnet.ibm.com Cc: fweisbec@gmail.com Link: http://lkml.kernel.org/r/1332513680-7870-1-git-send-email-jolsa@redhat.com Signed-off-by: Ingo Molnar

perf: Fix mmap_page capabilities and docs

2012-03-23T08:52:16Z

Complete the syscall-less self-profiling feature and address all complaints, namely: - capabilities, so we can detect what is actually available at runtime Add a capabilities field to perf_event_mmap_page to indicate what is actually available for use. - on x86: RDPMC weirdness due to being 40/48 bits and not sign-extending properly. - ABI documentation as to how all this stuff works. Also improve the documentation for the new features. Signed-off-by: Peter Zijlstra Cc: Stephane Eranian Cc: Vince Weaver Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Link: http://lkml.kernel.org/r/1332433596.2487.33.camel@twins Signed-off-by: Ingo Molnar

Merge branch 'for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2012-03-21T01:11:21Z

Pull cgroup changes from Tejun Heo: "Out of the 8 commits, one fixes a long-standing locking issue around tasklist walking and others are cleanups." * 'for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: Walk task list under tasklist_lock in cgroup_enable_task_cg_list cgroup: Remove wrong comment on cgroup_enable_task_cg_list() cgroup: remove cgroup_subsys argument from callbacks cgroup: remove extra calls to find_existing_css_set cgroup: replace tasklist_lock with rcu_read_lock cgroup: simplify double-check locking in cgroup_attach_proc cgroup: move struct cgroup_pidlist out from the header file cgroup: remove cgroup_attach_task_current_cg()

perf: Add callback to flush branch_stack on context switch

2012-03-05T13:55:42Z

With branch stack sampling, it is possible to filter by priv levels. In system-wide mode, that means it is possible to capture only user level branches. The builtin SW LBR filter needs to disassemble code based on LBR captured addresses. For that, it needs to know the task the addresses are associated with. Because of context switches, the content of the branch stack buffer may contain addresses from different tasks. We need a callback on context switch to either flush the branch stack or save it. This patch adds a new callback in struct pmu which is called during context switches. The callback is called only when necessary. That is when a system-wide context has, at least, one event which uses PERF_SAMPLE_BRANCH_STACK. The callback is never called for per-thread context. In this version, the Intel x86 code simply flushes (resets) the LBR on context switches (fills it with zeroes). Those zeroed branches are then filtered out by the SW filter. Signed-off-by: Stephane Eranian Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1328826068-11713-11-git-send-email-eranian@google.com Signed-off-by: Ingo Molnar

perf: Disable PERF_SAMPLE_BRANCH_* when not supported

2012-03-05T13:55:42Z

PERF_SAMPLE_BRANCH_* is disabled for: - SW events (sw counters, tracepoints) - HW breakpoints - ALL but Intel x86 architecture - AMD64 processors Signed-off-by: Stephane Eranian Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1328826068-11713-10-git-send-email-eranian@google.com Signed-off-by: Ingo Molnar

perf: Add generic taken branch sampling support

2012-03-05T13:55:39Z

This patch adds the ability to sample taken branches to the perf_event interface. The ability to capture taken branches is very useful for all sorts of analysis. For instance, basic block profiling, call counts, statistical call graph. This new capability requires hardware assist and as such may not be available on all HW platforms. On Intel x86 it is implemented on top of the Last Branch Record (LBR) facility. To enable taken branches sampling, the PERF_SAMPLE_BRANCH_STACK bit must be set in attr->sample_type. Sampled taken branches may be filtered by type and/or priv levels. The patch adds a new field, called branch_sample_type, to the perf_event_attr structure. It contains a bitmask of filters to apply to the sampled taken branches. Filters may be implemented in HW. If the HW filter does not exist or is not good enough, some arch may also implement a SW filter. The following generic filters are currently defined: - PERF_SAMPLE_USER only branches whose targets are at the user level - PERF_SAMPLE_KERNEL only branches whose targets are at the kernel level - PERF_SAMPLE_HV only branches whose targets are at the hypervisor level - PERF_SAMPLE_ANY any type of branches (subject to priv levels filters) - PERF_SAMPLE_ANY_CALL any call branches (may incl. syscall on some arch) - PERF_SAMPLE_ANY_RET any return branches (may incl. syscall returns on some arch) - PERF_SAMPLE_IND_CALL indirect call branches Obviously filter may be combined. The priv level bits are optional. If not provided, the priv level of the associated event are used. It is possible to collect branches at a priv level different from the associated event. Use of kernel, hv priv levels is subject to permissions and availability (hv). The number of taken branch records present in each sample may vary based on HW, the type of sampled branches, the executed code. Therefore each sample contains the number of taken branches it contains. Signed-off-by: Stephane Eranian Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1328826068-11713-2-git-send-email-eranian@google.com Signed-off-by: Ingo Molnar

Merge branch 'perf/urgent' into perf/core

2012-03-05T08:20:08Z

Conflicts: tools/perf/builtin-record.c tools/perf/builtin-top.c tools/perf/perf.h tools/perf/util/top.h Merge reason: resolve these cherry-picking conflicts. Signed-off-by: Ingo Molnar

static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]()

2012-02-24T09:05:59Z

So here's a boot tested patch on top of Jason's series that does all the cleanups I talked about and turns jump labels into a more intuitive to use facility. It should also address the various misconceptions and confusions that surround jump labels. Typical usage scenarios: #include struct static_key key = STATIC_KEY_INIT_TRUE; if (static_key_false(&key)) do unlikely code else do likely code Or: if (static_key_true(&key)) do likely code else do unlikely code The static key is modified via: static_key_slow_inc(&key); ... static_key_slow_dec(&key); The 'slow' prefix makes it abundantly clear that this is an expensive operation. I've updated all in-kernel code to use this everywhere. Note that I (intentionally) have not pushed through the rename blindly through to the lowest levels: the actual jump-label patching arch facility should be named like that, so we want to decouple jump labels from the static-key facility a bit. On non-jump-label enabled architectures static keys default to likely()/unlikely() branches. Signed-off-by: Ingo Molnar Acked-by: Jason Baron Acked-by: Steven Rostedt Cc: a.p.zijlstra@chello.nl Cc: mathieu.desnoyers@efficios.com Cc: davem@davemloft.net Cc: ddaney.cavm@gmail.com Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20120222085809.GA26397@elte.hu Signed-off-by: Ingo Molnar

perf: Fix double start/stop in x86_pmu_start()

2012-02-07T15:58:56Z

The following patch fixes a bug introduced by the following commit: e050e3f0a71b ("perf: Fix broken interrupt rate throttling") The patch caused the following warning to pop up depending on the sampling frequency adjustments: ------------[ cut here ]------------ WARNING: at arch/x86/kernel/cpu/perf_event.c:995 x86_pmu_start+0x79/0xd4() It was caused by the following call sequence: perf_adjust_freq_unthr_context.part() { stop() if (delta > 0) { perf_adjust_period() { if (period > 8*...) { stop() ... start() } } } start() } Which caused a double start and a double stop, thus triggering the assert in x86_pmu_start(). The patch fixes the problem by avoiding the double calls. We pass a new argument to perf_adjust_period() to indicate whether or not the event is already stopped. We can't just remove the start/stop from that function because it's called from __perf_event_overflow where the event needs to be reloaded via a stop/start back-toback call. The patch reintroduces the assertion in x86_pmu_start() which was removed by commit: 84f2b9b ("perf: Remove deprecated WARN_ON_ONCE()") In this second version, we've added calls to disable/enable PMU during unthrottling or frequency adjustment based on bug report of spurious NMI interrupts from Eric Dumazet. Reported-and-tested-by: Eric Dumazet Signed-off-by: Stephane Eranian Acked-by: Peter Zijlstra Cc: markus@trippelsdorf.de Cc: paulus@samba.org Link: http://lkml.kernel.org/r/20120207133956.GA4932@quad [ Minor edits to the changelog and to the code ] Signed-off-by: Ingo Molnar