linux-kernel - Re: [PATCH 05/11] perf intel-pt: Use itrace error flags to suppress some errors

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Message-ID: <3271e2cf-490b-5391-19e0-e1b019bfba1f@intel.com>
Date:   Thu, 9 Jul 2020 21:13:38 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Andi Kleen <ak@...ux.intel.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/11] perf intel-pt: Use itrace error flags to suppress
 some errors

On 9/07/20 8:50 pm, Andi Kleen wrote:
> On Thu, Jul 09, 2020 at 08:36:22PM +0300, Adrian Hunter wrote:
>> The itrace "e" option may be followed by a number which has the
>> following effect for Intel PT:
>> 	1	Suppress overflow events
>> 	2	Suppress trace data lost events
>> The values may be combined by bitwise OR'ing them.
>>
>> Suppressing those errors can be useful for testing and debugging
>> because they are not due to decoding.
> 
> I suspect it will be useful to more than just decoding and debugging.
> 
> But the number is not a nice user interface.
> 
> How about e[....] 
> 
> like e[ol] 

Do you mean literally square-brackets? If you were really unlucky you might
get pathname expansion with that.

> 
> Also it's a bit unusual that this disables instead of enables, but ok.
> 
> -Andi
>