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From: Steven Rostedt <rostedt@goodmis.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Jiri Olsa <jolsa@kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	linux-trace-users@vger.kernel.org
Subject: Re: [RFC][PATCH 2/4] tracing: Use pid bitmap instead of a pid array for set_event_pid
Date: Tue, 19 Apr 2016 15:41:13 -0400	[thread overview]
Message-ID: <20160419154113.64f146dc@grimm.local.home> (raw)
In-Reply-To: <4ACF15B6-D344-4647-9CF8-CEDE5BF5EF70@zytor.com>

On Tue, 19 Apr 2016 11:57:32 -0700
"H. Peter Anvin" <hpa@zytor.com> wrote:

> Also, I understand there is one of these bitmaps per ring buffer, and
> the ring buffer is in the tens of megabytes.

Right, there's only one bitmap per tracing instance, which in most
cases is just one (I know of people who make more). And by default, the
tracing buffer is 1.4 megs per CPU.

If you have a pid_max of the max size, I highly doubt you will be doing
that on a single CPU machine. If you have 48 CPUs, the ring buffer will
be 1.4 * 48 megs, making the 1/2 meg bitmap a nit.

I will say, there may be two bitmaps soon, because I plan on adding
this same code to the function tracer logic.

-- Steve

  parent reply	other threads:[~2016-04-19 19:41 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-19 14:34 [RFC][PATCH 0/4] tracing: Add event-fork to trace tasks children Steven Rostedt
2016-04-19 14:34 ` [RFC][PATCH 1/4] tracing: Rename check_ignore_pid() to ignore_this_task() Steven Rostedt
2016-04-19 14:34 ` [RFC][PATCH 2/4] tracing: Use pid bitmap instead of a pid array for set_event_pid Steven Rostedt
     [not found]   ` <1694657549.62933.1461084928341.JavaMail.zimbra@efficios.com>
2016-04-19 17:19     ` Steven Rostedt
     [not found]       ` <4ACF15B6-D344-4647-9CF8-CEDE5BF5EF70@zytor.com>
2016-04-19 19:41         ` Steven Rostedt [this message]
     [not found]           ` <2093660141.63332.1461097049611.JavaMail.zimbra@efficios.com>
2016-04-19 20:50             ` Steven Rostedt
     [not found]               ` <568915868.63547.1461100941927.JavaMail.zimbra@efficios.com>
2016-04-19 22:49                 ` Steven Rostedt
     [not found]                   ` <2099338042.63665.1461106754326.JavaMail.zimbra@efficios.com>
2016-04-19 23:06                     ` Steven Rostedt
     [not found]   ` <20160422024530.GA1790@sejong>
2016-04-22 15:30     ` Steven Rostedt
2016-04-19 14:34 ` [RFC][PATCH 3/4] tracing: Add infrastructure to allow set_event_pid to follow children Steven Rostedt
     [not found]   ` <1887707510.62932.1461084911586.JavaMail.zimbra@efficios.com>
2016-04-19 17:13     ` Steven Rostedt
2016-04-19 14:34 ` [RFC][PATCH 4/4] tracing: Update the documentation to describe "event-fork" option Steven Rostedt
     [not found] ` <5716E3E8.7000609@redhat.com>
2016-04-20  2:30   ` [RFC][PATCH 0/4] tracing: Add event-fork to trace tasks children Steven Rostedt

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