Re: [Xen-devel] [PATCH v1] xen: make tracebuffer configurable

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.06.19 at 12:49, <George.Dunlap@xxxxxxxxxx> wrote:
>> On Jun 4, 2019, at 1:44 AM, Baodong Chen <chenbaodong@xxxxxxxxxx> wrote:
>> --- a/xen/common/Kconfig
>> +++ b/xen/common/Kconfig
>> @@ -368,4 +368,16 @@ config DOM0_MEM
>> 
>>        Leave empty if you are not sure what to specify.
>> 
>> +config TRACEBUFFER
>> +    bool "Enable trace event logs"  if EXPERT = "y"
>> +    ---help---
>> +      Xen internal running status(trace event) will be saved to trace memory
>> +      when enabled. trace event data and config params can be read/changed
>> +      by system control hypercall at run time.
>> +
>> +      This is used to record xen internal running status.
>> +      with a litte performance overhead.
>> +      Can be set to 'N' if you dont want this function.
>> +      When not configured, 'XEN_STSCTL_tbuf_op' command will result 
>> 'ENOSYS’.
> 
> I think this would look better something like this:
> 
> “Enable tracing infrastructure”
> 
> “Enable in tracing infrastructure and pre-defined tracepoints within Xen.  
> This will allow live information about Xen’s execution and performance to be 
> collected at run time for debugging or performance analysis.  Memory and 
> execution overhead when not active is minimal."
> 
> Also, I’m not 100% familiar with the kconfig syntax — I think we want 
> tracing enabled by default unless actively disabled; is that what will happen 
> here?  Or will it only be enabled if EXPERT == ‘y’?

Oh, indeed - there's a "default y" missing.

Jan


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