From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43698) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cMJ9q-0004OQ-0M for qemu-devel@nongnu.org; Wed, 28 Dec 2016 13:41:03 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cMJ9m-0001Eg-Pe for qemu-devel@nongnu.org; Wed, 28 Dec 2016 13:41:02 -0500 Received: from roura.ac.upc.edu ([147.83.33.10]:48432 helo=roura.ac.upc.es) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cMJ9m-0001EB-Ct for qemu-devel@nongnu.org; Wed, 28 Dec 2016 13:40:58 -0500 From: =?utf-8?b?TGx1w61z?= Vilanova Date: Wed, 28 Dec 2016 19:40:54 +0100 Message-Id: <148295045448.19871.9819696634619157347.stgit@fimbulvetr.bsc.es> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PATCH v6 0/7] trace: [tcg] Optimize per-vCPU tracing states with separate TB caches List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Eric Blake , Eduardo Habkost , Stefan Hajnoczi Optimizes tracing of events with the 'tcg' and 'vcpu' properties (e.g., m= emory accesses), making it feasible to statically enable them by default on all= QEMU builds. Some quick'n'dirty numbers with 400.perlbench (SPECcpu2006) on the train = input (medium size - suns.pl) and the guest_mem_before event: * vanilla, statically disabled real 0m2,259s user 0m2,252s sys 0m0,004s * vanilla, statically enabled (overhead: 2.18x) real 0m4,921s user 0m4,912s sys 0m0,008s * multi-tb, statically disabled (overhead: 0.99x) [within noise range] real 0m2,228s user 0m2,216s sys 0m0,008s * multi-tb, statically enabled (overhead: 0.99x) [within noise range] real 0m2,229s user 0m2,224s sys 0m0,004s Right now, events with the 'tcg' property always generate TCG code to tra= ce that event at guest code execution time, where the event's dynamic state is ch= ecked. This series adds a performance optimization where TCG code for events wit= h the 'tcg' and 'vcpu' properties is not generated if the event is dynamically disabled. This optimization raises two issues: * An event can be dynamically disabled/enabled after the corresponding TC= G code has been generated (i.e., a new TB with the corresponding code should b= e used). * Each vCPU can have a different dynamic state for the same event (i.e., = tracing the memory accesses of only one process pinned to a vCPU). To handle both issues, this series integrates the dynamic tracing event s= tate into the TB hashing function, so that vCPUs tracing different events will= use separate TBs. Note that only events with the 'vcpu' property are used for hashing (as stored in the bitmap of CPUState->trace_dstate). This makes dynamic event state changes on vCPUs very efficient, since the= y can use TBs produced by other vCPUs while on the same event state combination= (or produced by the same vCPU, earlier). Discarded alternatives: * Emitting TCG code to check if an event needs tracing, where we should s= till move the tracing call code to either a cold path (making tracing perfor= mance worse), or leave it inlined (making non-tracing performance worse). * Eliding TCG code only when *zero* vCPUs are tracing an event, since ena= bling it on a single vCPU will impact the performance of all other vCPUs that= are not tracing that event. Signed-off-by: Llu=C3=ADs Vilanova --- Changes in v6 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D * Check hashing size error with QEMU_BUILD_BUG_ON [Richard Henderson]. Changes in v5 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D * Move define into "qemu-common.h" to allow compilation of tests. Changes in v4 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D * Incorporate trace_dstate into the TB hashing function instead of using multiple physical TB caches [suggested by Richard Henderson]. Changes in v3 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D * Rebase on 0737f32daf. * Do not use reserved symbol prefixes ("__") [Stefan Hajnoczi]. * Refactor trace_get_vcpu_event_count() to be inlinable. * Optimize cpu_tb_cache_set_requested() (hottest path). Changes in v2 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D * Fix bitmap copy in cpu_tb_cache_set_apply(). * Split generated code re-alignment into a separate patch [Daniel P. Berr= ange]. Llu=C3=ADs Vilanova (7): exec: [tcg] Refactor flush of per-CPU virtual TB cache trace: Make trace_get_vcpu_event_count() inlinable trace: [tcg] Delay changes to dynamic state when translating exec: [tcg] Use different TBs according to the vCPU's dynamic traci= ng state trace: [tcg] Do not generate TCG code to trace dinamically-disabled= events trace: [tcg,trivial] Re-align generated code trace: [trivial] Statically enable all guest events cpu-exec.c | 52 ++++++++++++++++++++++++= +++--- cputlb.c | 2 + include/exec/exec-all.h | 11 ++++++ include/exec/tb-hash-xx.h | 8 ++++- include/exec/tb-hash.h | 5 ++- include/qemu-common.h | 3 ++ include/qom/cpu.h | 7 ++++ qom/cpu.c | 4 ++ scripts/tracetool/__init__.py | 1 + scripts/tracetool/backend/dtrace.py | 2 + scripts/tracetool/backend/ftrace.py | 20 ++++++------ scripts/tracetool/backend/log.py | 17 +++++----- scripts/tracetool/backend/simple.py | 2 + scripts/tracetool/backend/syslog.py | 6 ++- scripts/tracetool/backend/ust.py | 2 + scripts/tracetool/format/h.py | 24 ++++++++++---- scripts/tracetool/format/tcg_h.py | 19 +++++++++-- scripts/tracetool/format/tcg_helper_c.py | 3 +- tests/qht-bench.c | 2 + trace-events | 6 ++- trace/control-internal.h | 5 +++ trace/control-target.c | 14 +++++++- trace/control.c | 9 +---- trace/control.h | 5 ++- translate-all.c | 30 +++++++++++++---- 25 files changed, 195 insertions(+), 64 deletions(-) To: qemu-devel@nongnu.org Cc: Stefan Hajnoczi Cc: Eduardo Habkost Cc: Eric Blake