Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935254AbaKNNoL (ORCPT ); Fri, 14 Nov 2014 08:44:11 -0500 Received: from mga03.intel.com ([134.134.136.65]:10568 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933815AbaKNNoI (ORCPT ); Fri, 14 Nov 2014 08:44:08 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,386,1413270000"; d="scan'208";a="607841356" From: Alexander Shishkin To: Peter Zijlstra Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Robert Richter , Frederic Weisbecker , Mike Galbraith , Paul Mackerras , Stephane Eranian , Andi Kleen , kan.liang@intel.com, adrian.hunter@intel.com, markus.t.metzger@intel.com, mathieu.poirier@linaro.org, acme@infradead.org, Alexander Shishkin Subject: [PATCH v8 00/14] perf: Add infrastructure and support for Intel PT Date: Fri, 14 Nov 2014 15:43:33 +0200 Message-Id: <1415972627-37514-1-git-send-email-alexander.shishkin@linux.intel.com> X-Mailer: git-send-email 2.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter and all, Since there weren't too many review comments on the two previous versions, here's another one with a couple more fixes. [full description below the changelog] Changes since v7: * fixed a bug in aux allocation logic that caused more than requested pages to be allocated, * fixed pt_event_add() for snapshot mode, which would return an error in case of successful completion. Changes since v6: * replaced kref with atomic in aux refcounting this time for real, * added a small comment on capabilities/"caps" attribute group in PT pmu. Changes since v5: * dropped "bypass mask", bits that a privileged user could set in RTIT_CTL, * merged configuring and enabling RTIT_CTL writes, * fixed kernel-doc comments * if LBR/BTS events are present in the system, PT event creation is disallowed and vice versa, * fixed a bug with high order allocation under pressure, * fixed undoing vm_locked accounting in case of AUX allocation failure, * left out kernel counters for a separate series to keep this one concise. This patchset adds support for Intel Processor Trace (PT) extension [1] of Intel Architecture that allows the capture of information about software execution flow, to the perf kernel infrastructure. The single most notable thing is that while PT outputs trace data in a compressed binary format, it will still generate hundreds of megabytes of trace data per second per core. Decoding this binary stream takes 2-3 orders of magnitude the cpu time that it takes to generate it. These considerations make it impossible to carry out decoding in kernel space. Therefore, the trace data is exported to userspace as a zero-copy mapping that userspace can collect and store for later decoding. To address this, this patchset extends perf ring buffer with an "AUX space", which is allocated for hardware blocks such as PT to export their trace data with minimal overhead. This space can be configured via buffer's user page and mmapped from the same file descriptor with a given offset. Data can then be collected from it by reading the aux_head (write) pointer from the user page and updating aux_tail (read) pointer similarly to data_{head,tail} of the traditional perf buffer. There is an api between perf core and pmu drivers that wish to make use of this AUX space to export their data. For tracing blocks that don't support hardware scatter-gather tables, we provide high-order physically contiguous allocations to minimize the overhead needed for software double buffering and PMI pressure. This way we get a normal perf data stream that provides sideband information that is required to decode the trace data, such as MMAPs, COMMs etc, plus the actual trace in its own logical space. If the trace buffer is mapped writable, the driver will stop tracing when it fills up (aux_head approaches aux_tail), till data is read, aux_tail pointer is moved forward and an ioctl() is issued to re-enable tracing. If the trace buffer is mapped read only, the tracing will continue, overwriting older data, so that the buffer always contains the most recent data. Tracing can be stopped with an ioctl() and restarted once the data is collected. This patchset consists of necessary changes to the perf kernel infrastructure, and PT and BTS pmu drivers. The tooling support is not included in this series, however, it can be found in my github tree [2]. [1] chapter 36 of http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-manual-325462.pdf [2] http://github.com/virtuoso/linux-perf/tree/intel_pt Alexander Shishkin (13): perf: Add data_{offset,size} to user_page perf: Support high-order allocations for AUX space perf: Add a capability for AUX_NO_SG pmus to do software double buffering perf: Add a pmu capability for "exclusive" events perf: Add AUX record perf: Add api for pmus to write to AUX area perf: Support overwrite mode for AUX area perf: Add wakeup watermark control to AUX area x86: Add Intel Processor Trace (INTEL_PT) cpu feature detection x86: perf: Intel PT and LBR/BTS are mutually exclusive x86: perf: intel_pt: Intel PT PMU driver x86: perf: intel_bts: Add BTS PMU driver perf: add ITRACE_START record to indicate that tracing has started Peter Zijlstra (1): perf: Add AUX area to ring buffer for raw data streams arch/x86/include/asm/cpufeature.h | 1 + arch/x86/include/uapi/asm/msr-index.h | 18 + arch/x86/kernel/cpu/Makefile | 1 + arch/x86/kernel/cpu/intel_pt.h | 131 ++++ arch/x86/kernel/cpu/perf_event.c | 43 ++ arch/x86/kernel/cpu/perf_event.h | 49 ++ arch/x86/kernel/cpu/perf_event_intel.c | 40 +- arch/x86/kernel/cpu/perf_event_intel_bts.c | 525 ++++++++++++++ arch/x86/kernel/cpu/perf_event_intel_ds.c | 3 +- arch/x86/kernel/cpu/perf_event_intel_pt.c | 1082 ++++++++++++++++++++++++++++ arch/x86/kernel/cpu/scattered.c | 1 + include/linux/perf_event.h | 47 +- include/uapi/linux/perf_event.h | 59 +- kernel/events/core.c | 268 ++++++- kernel/events/internal.h | 33 + kernel/events/ring_buffer.c | 327 ++++++++- 16 files changed, 2577 insertions(+), 51 deletions(-) create mode 100644 arch/x86/kernel/cpu/intel_pt.h create mode 100644 arch/x86/kernel/cpu/perf_event_intel_bts.c create mode 100644 arch/x86/kernel/cpu/perf_event_intel_pt.c -- 2.1.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/