Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 06 Nov 2018 15:36:47 -0800 (PST)
Message-Id: <20181106.153647.1701013551426767213.davem@davemloft.net>
To:     ast@fb.com
Cc:     songliubraving@fb.com, dsahern@gmail.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Kernel-team@fb.com, ast@kernel.org,
        daniel@iogearbox.net, peterz@infradead.org, acme@kernel.org
Subject: Re: [RFC perf,bpf 5/5] perf util: generate bpf_prog_info_event for
 short living bpf programs
From:   David Miller <davem@davemloft.net>
In-Reply-To: <27fc8327-3390-ba5a-6063-89c9e7165e7b@fb.com>
References: <b984776a-ce69-ab16-ed87-1cea89c9d79a@gmail.com>
        <6C5A9FBD-F50D-444C-9038-E9557EC850D2@fb.com>
        <27fc8327-3390-ba5a-6063-89c9e7165e7b@fb.com>
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Alexei Starovoitov <ast@fb.com>
Date: Tue, 6 Nov 2018 23:29:07 +0000

> I think concerns with perf overhead from collecting bpf events
> are unfounded.
> I would prefer for this flag to be on by default.

I will sit in userspace looping over bpf load/unload and see how the
person trying to monitor something else with perf feels about that.

Really, it is inappropriate to turn this on by default, I completely
agree with David Ahern.

It's hard enough, _AS IS_, for me to fight back all of the bloat that
is in perf right now and get it back to being able to handle simple
full workloads without dropping events..

Every new event type like this sets us back.

If people want to monitor new things, or have new functionality, fine.

But not by default, please.