Messages in this thread | | | Date | Thu, 17 Sep 2020 18:12:19 +0800 | From | Leo Yan <> | Subject | Re: [PATCHv3] perf kvm: add kvm-stat for arm64 |
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Add Marc at this time, sorry for spamming.
On Thu, Sep 17, 2020 at 06:09:50PM +0800, Leo Yan wrote: > [ + Marc ] > > On Thu, Sep 17, 2020 at 09:36:45AM +0900, Sergey Senozhatsky wrote: > > [...] > > > diff --git a/tools/perf/arch/arm64/util/kvm-stat.c b/tools/perf/arch/arm64/util/kvm-stat.c > > new file mode 100644 > > index 000000000000..32e58576f186 > > --- /dev/null > > +++ b/tools/perf/arch/arm64/util/kvm-stat.c > > @@ -0,0 +1,86 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +#include <errno.h> > > +#include <memory.h> > > +#include "../../util/evsel.h" > > +#include "../../util/kvm-stat.h" > > +#include "arm64_exception_types.h" > > +#include "debug.h" > > + > > +define_exit_reasons_table(arm64_exit_reasons, kvm_arm_exception_type); > > +define_exit_reasons_table(arm64_trap_exit_reasons, kvm_arm_exception_class); > > + > > +const char *kvm_trap_exit_reason = "esr_ec"; > > +const char *vcpu_id_str = "id"; > > On Arm64, ftrace tracepoint "kvm_entry" doesn't contain the field "id" > or field "vcpu_id", thus it always reads out the "id" is 0 and it is > recorded into Perf's structure vcpu_event_record::vcpu_id and assigned > to perf thread's private data "thread::private". > > With current code, it will not mess up different vcpus' samples because > now the samples are analyzed based on thread context, but since all > threads' "vcpu_id" is zero, thus all samples are accounted for > "vcpu_id=0" and cannot print out correct result with option "--vcpu": > > > $ perf kvm stat report --vcpu 4 > > Analyze events for all VMs, VCPU 4: > > VM-EXIT Samples Samples% Time% Min Time Max Time Avg time > > Total Samples:0, Total events handled time:0.00us. > > > This is an issue I observed, if we want to support option "--vcpu", > seems we need to change ftrace event for "kvm_entry", but this will > break ABI. > > Essentially, this issue is caused by different archs using different > format for ftrace event "kvm_entry", on x86 it contains feild > "vcpu_id" but arm64 only just records "vcpu_pc". > > @Marc, @Will, do you have any suggestion for this? Do you think it's > feasible to add a new field "vcpu_id" into the tracepoint "kvm_entry" > for Arm64's version? > > Thanks, > Leo
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