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Subject: Re: [PATCH 03/10] perf sched timehist: Handle zero sample->tid
 properly
To: Namhyung Kim <namhyung@kernel.org>
References: <20161206034010.6499-1-namhyung@kernel.org>
 <20161206034010.6499-4-namhyung@kernel.org>
 <c6d20e6b-1558-640c-0316-3e509f2b8e93@gmail.com>
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Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
        Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>,
        Jiri Olsa <jolsa@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        Andi Kleen <andi@firstfloor.org>, Minchan Kim <minchan@kernel.org>
From: David Ahern <dsahern@gmail.com>
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Date: Mon, 5 Dec 2016 20:01:51 -0800
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On 12/5/16 7:59 PM, Namhyung Kim wrote:
> No, I didn't investigate it yet.  Looking at the original code, you
> seemed to have same issue and workaround like checking prev_pid or
> callchains, right?

most likely. As I responded on another patch, the sched timehist command has been used for years on a range of OS'es and kernel versions. Most of the oddities you see are (sometime quick) fixes to strange differences in kernel versions.