From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e34.co.us.ibm.com (e34.co.us.ibm.com [32.97.110.152]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 6B2B61A17B4 for ; Fri, 4 Sep 2015 13:09:44 +1000 (AEST) Received: from /spool/local by e34.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 3 Sep 2015 21:09:42 -0600 Received: from b03cxnp08027.gho.boulder.ibm.com (b03cxnp08027.gho.boulder.ibm.com [9.17.130.19]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 2988219D801C for ; Thu, 3 Sep 2015 21:00:34 -0600 (MDT) Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t8439d7q40632348 for ; Thu, 3 Sep 2015 20:09:39 -0700 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t8439cIJ004940 for ; Thu, 3 Sep 2015 21:09:38 -0600 From: Sukadev Bhattiprolu To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Michael Ellerman Cc: , linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org Subject: [PATCH v6 0/10] perf: Implement group-read of events using txn interface Date: Thu, 3 Sep 2015 20:07:43 -0700 Message-Id: <1441336073-22750-1-git-send-email-sukadev@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Unlike normal hardware PMCs, the 24x7 counters in Power8 are stored in memory and accessed via a hypervisor call (HCALL). A major aspect of the HCALL is that it allows retireving _several_ counters at once (unlike regular PMCs, which are read one at a time). By reading several counters at once, we can get a more consistent snapshot of the system. This patchset extends the transaction interface to accomplish submitting several events to the PMU and have the PMU read them all at once. User is expected to submit the set of events they want to read as an "event group". In the kernel, we submit each event to the PMU using the following logic (from Peter Zijlstra). pmu->start_txn(pmu, PMU_TXN_READ); leader->read(); for_each_sibling() sibling->read(); pmu->commit_txn(); where: - the ->read()s queue events to be submitted to the hypervisor, and, - the ->commit_txn() issues the HCALL, retrieves the result and updates the event count. Architectures/PMUs that don't need/implement PMU_TXN_READ type of transactions, simply ignore the ->start_txn() and ->commit_txn() and continue to read the counters one at a time in the ->read() call. Compile/touch tested on x86. Need help testing on s390 and Sparc. Thanks to Peter Zijlstra for his input/code. Changelog[v6] - [Peter Zijlstra] Use the new ->txn_flags to determine if we are in a transaction and to skip the schedulability tests. This results in PERF_EVENT_TXN flag being unused and can be dropped. Once PERF_EVENT_TXN is not used, several architectures no longer need the cpuhw->group_flag so drop that as well. - [Peter Zijlstra] Change the type of txn_flags from 'int' to 'unsigned int'. - [Peter Zijlstra] Add a WARN_ON_ONCE() if the state of txn_flags is not what we expect. - Rebase to 4.2.0. Changelog[v5] - Invert the sibling-child loop nesting in perf-read-group (re-org code and drop the patch that defined perf_event_aggregate()). Changelog[v4] - Ensure all the transactions operations happen on the same CPU so PMUs can use per-CPU buffers for the transaction. - Add lockdep assert and fix a locking issue in perf_read_group(). Changelog [v3] - Simple changes/reorg of patchset to split/rename functions - [Peter Zijlstra] Save the transaction flags in ->start_txn() and drop the flags parameter from ->commit_txn() and ->cancel_txn(). - [Peter Zijlstra] The nop txn interfaces don't need to disable/enable PMU for PERF_PMU_TXN_READ transactions. Changelog [v2] - Use the transaction interface unconditionally to avoid special-case code. Architectures/PMUs that don't need the READ transaction types simply ignore the ->start_txn() and ->commit_txn() calls. Peter Zijlstra (2): perf: Add group reads to perf_event_read() perf: Invert perf_read_group() loops Peter Zijlstra (Intel) (1): perf: Rename perf_event_read_{one,group}, perf_read_hw Sukadev Bhattiprolu (7): perf/sparc: Remove unnecessary assignment perf: Add a flags parameter to pmu txn interfaces perf: Split perf_event_read() and perf_event_count() perf: Add return value for perf_event_read(). Define PERF_PMU_TXN_READ interface powerpc/perf/hv-24x7: Use PMU_TXN_READ interface perf: Drop PERF_EVENT_TXN arch/powerpc/perf/core-book3s.c | 36 +++++-- arch/powerpc/perf/hv-24x7.c | 166 +++++++++++++++++++++++++++++- arch/s390/kernel/perf_cpum_cf.c | 35 ++++++- arch/sparc/kernel/perf_event.c | 32 ++++-- arch/x86/kernel/cpu/perf_event.c | 39 +++++-- arch/x86/kernel/cpu/perf_event.h | 2 +- include/linux/perf_event.h | 15 ++- kernel/events/core.c | 210 +++++++++++++++++++++++++++++--------- 8 files changed, 456 insertions(+), 79 deletions(-) -- 1.7.9.5