netdev - Re: [RFC PATCH] perf, bpf: Retain kernel executable code in memory to aid Intel PT tracing

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Message-ID: <20190211081840.j3vhyp3cffftb6m2@ast-mbp>
Date:   Mon, 11 Feb 2019 00:18:42 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>, Song Liu <songliubraving@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [RFC PATCH] perf, bpf: Retain kernel executable code in memory
 to aid Intel PT tracing

On Mon, Feb 11, 2019 at 09:54:01AM +0200, Adrian Hunter wrote:
> 
> Which is not really a real use-case.
..
> > perf analysis with PT becomes inaccurate and main goal
> > of retaining accurate instruction info is not achieved.
> 
> For the majority of real use-cases, yes it is.

In our fleet not a single server is using Intel PT, yet you're
proposing to penalize all of them with shrinker-based JIT freeing?
There is no negotiation here.
NACK