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From: Steven Rostedt <rostedt@goodmis.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Nicolas Boichat <drinkcat@chromium.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>, Jason Gunthorpe <jgg@ziepe.ca>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	Peter Zijlstra <peterz@infradead.org>,
	Vinod Koul <vkoul@kernel.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Tiezhu Yang <yangtiezhu@loongson.cn>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Guilherme G . Piccoli" <gpiccoli@canonical.com>,
	Will Deacon <will@kernel.org>,
	Douglas Anderson <dianders@chromium.org>,
	Guenter Roeck <groeck@chromium.org>,
	bpf@vger.kernel.org
Subject: Re: [PATCH] kernel/trace: Add TRACING_ALLOW_PRINTK config option
Date: Sun, 28 Jun 2020 15:00:15 -0400	[thread overview]
Message-ID: <20200628150015.363009dd@oasis.local.home> (raw)
In-Reply-To: <20200628144616.52f09152@oasis.local.home>

On Sun, 28 Jun 2020 14:46:16 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> > We added a bunch of code to libbcc in the past to support instances,
> > but eventually removed it all due to memory overhead per instance.
> > If I recall it was ~8Mbyte per instance. That was couple years ago.  
> 
> I'd like to see where that 8 MB per instance came from. You can control
> the size of the instance buffers. If size is still an issue, I'll be
> happy to work with you to fix it.

Looks to be the duplication of the event directory tree. There's a lot
of duplicate data there. Instead of just punting and saying "instances
are too large" perhaps you could get someone to look at a way to
consolidate that data? I'm sure there's a lot of ways to help here.

Or you can just create a new event called bpf_printk() that passes in
and records a string and enable that automatically when a bpf module
has it. That could work as well.

In either case, your use of trace_printk() is an abuse of its purpose.

-- Steve

  reply	other threads:[~2020-06-28 19:00 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-24  8:45 [PATCH] kernel/trace: Add TRACING_ALLOW_PRINTK config option Nicolas Boichat
2020-06-24 13:57 ` Jason Gunthorpe
2020-06-25  1:13   ` Nicolas Boichat
2020-06-24 16:04 ` Steven Rostedt
2020-06-24 17:25   ` Alexei Starovoitov
2020-06-25  2:00     ` Nicolas Boichat
2020-06-25  3:59       ` Alexei Starovoitov
2020-06-26 22:14         ` Steven Rostedt
2020-06-28 17:27           ` Alexei Starovoitov
2020-06-28 18:46             ` Steven Rostedt
2020-06-28 19:00               ` Steven Rostedt [this message]
2020-06-28 19:21               ` Alexei Starovoitov
2020-06-28 19:43                 ` Steven Rostedt
2020-06-28 22:02                   ` Alexei Starovoitov
2020-06-28 22:28                     ` Steven Rostedt
2020-06-28 23:43                       ` Steven Rostedt
2020-06-30  5:16                         ` Alexei Starovoitov
2020-06-30 12:39                           ` Steven Rostedt
2020-06-25  1:32   ` Nicolas Boichat
2020-06-24 17:37 ` kernel test robot
2020-06-24 19:07 ` kernel test robot

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