[RFC] perf: EBNF for event syntax
From: Lin Ming
Date: Tue Mar 22 2011 - 23:37:32 EST
Hi, all
On Thu, Mar 17, 2011 at 2:02 AM, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
> How about we start writing proper EBNF syntax rules for this stuff, its
> getting seriously out of hand.
http://marc.info/?l=linux-kernel&m=130029871318866&w=2
As Peter suggested, I wrote a simple EBNF for event syntax, as below.
My first plan is to pass in extra config value for some events,
for example, offcore response and load latency.
perf record -e r100b(0004):p
As above, the extra config value 0004 is passed in the parentheses.
The EBNF
========
EventList := Event [',' EventList]
Event := HardwareEvent |
RawEvent |
SoftwareEvent |
TracepointEvent |
HardwareBreakpointEvent
HardwareEvent := HardwareEventName [ExtraConfig] [Modifer]
HardwareEventName := 'cpu-cycles' | 'cycles' | 'instructions' /* and so on ...*/
ExtraConfig := '(' ConfigValue [',' ConfigValue] ')'
ConfigValue := HexNumber
RawEvent := RawSeperator RawCode [ExtraConfig] [Modifer]
RawSeperator := 'r'
RawCode := HexNumber
SoftwareEvent := SoftwareEventName
SoftwareEventName := 'cpu-clock' | 'task-clock' | 'faults' /* and so on ...*/
TracepointEvent := SubsystemName ':' TracepointName
SubsystemName := /* All AsciiString except the pre-defined hardware/software/cache events name and BreakpointSeparator */
TracepointName := '*' | AsciiString
HardwareBreakpointEvent := BreakpointSeparator BreakpointAddress [':' AccessType]
BreakpointSeparator := 'mem:'
BreakpointAddress := HexNumber
AccessType := 'r' | 'w' | 'x'
Modifier := ModifierSperator ModifierList
ModifierSperator := ':'
ModifierList := ModifierItem ModifierList
ModifierItem := {PreciseModifer} | kernelModifer | UserModifer | HypervisorModifer
PreciseModifer := 'p' /* Can be multiple PreciseModifers */
kernelModifer := 'k'
UserModifer := 'u'
HypervisorModifer := 'h'
Some valid examples
===================
Hardware events with modifiers,
cycles:pk,instructions:u
Raw event with extra config values and/or modifiers,
r0110(40A0):pu
r0110(40A0,40A1):k
Software event,
cpu-clock,faults
Hardware breakpoint events:
mem:400346
mem:800A03:w
Some invalid examples
=====================
r0110(40A0,40A1,40A2), invalid, only 2 extra config values are allowed
cpu-clock:p, invalid, software event does not have precise modifier
Any comments?
Thanks,
Lin Ming
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