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From: Steven Rostedt <rostedt@goodmis.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
	Juergen Gross <jgross@suse.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
	Joel Fernandes <joel@joelfernandes.org>,
	He Zhe <zhe.he@windriver.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Clark Williams <williams@redhat.com>
Subject: Re: [RFC][PATCH] tracing/x86: Save CR2 before tracing irqsoff on error_entry
Date: Thu, 21 Mar 2019 15:50:06 -0400	[thread overview]
Message-ID: <20190321155006.5288345f@gandalf.local.home> (raw)
In-Reply-To: <20190321193152.GB2490@worktop.programming.kicks-ass.net>

On Thu, 21 Mar 2019 20:31:52 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> > 
> > No I didn't. Some users only care about performance, but find memory
> > cheap.  
> 
> Because cache-misses are free?

If I ever did implement this, I would try to get all the data out of
line as much as possible, where only a nop would be inserted:

	jmp lockdep_code
	raw_locking
1:

[..]

lockdep_code:
	do all that lockdep needs
	raw_locking
	jmp 1b

and have that converted to:


	nop // jmp lockdep_code
	raw_locking
1:

when disabled. So the only extra pressure on the icache is the nop.

-- Steve

	

  reply	other threads:[~2019-03-21 19:50 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-21  2:15 [RFC][PATCH] tracing/x86: Save CR2 before tracing irqsoff on error_entry Steven Rostedt
2019-03-21  8:33 ` Peter Zijlstra
2019-03-21  9:02   ` Peter Zijlstra
2019-03-21 10:45     ` Peter Zijlstra
2019-03-21 13:32       ` Steven Rostedt
2019-03-21 13:55         ` Steven Rostedt
2019-03-21 17:23           ` Linus Torvalds
2019-03-21 17:22         ` Peter Zijlstra
2019-03-21 18:05           ` Andy Lutomirski
2019-03-21 18:10             ` Steven Rostedt
2019-03-21 18:27               ` Andy Lutomirski
2019-03-21 20:50                 ` Peter Zijlstra
2019-03-22  2:52                   ` Andy Lutomirski
2019-03-21 18:28               ` Peter Zijlstra
2019-03-21 18:55                 ` Steven Rostedt
2019-03-21 19:31                   ` Peter Zijlstra
2019-03-21 19:50                     ` Steven Rostedt [this message]
2019-03-21 20:03                       ` Peter Zijlstra
2019-03-21 20:11                         ` Steven Rostedt
2019-03-21 18:18             ` Linus Torvalds
2019-03-21 18:20               ` Andy Lutomirski
2019-03-21 18:25                 ` Linus Torvalds
2019-03-21 18:37                   ` Peter Zijlstra
2019-03-21 18:39                     ` Andy Lutomirski
2019-03-21 20:00                       ` Andrew Cooper
2019-03-21 20:35                         ` Steven Rostedt
2019-03-21 18:38                   ` Andy Lutomirski
2019-03-21 18:42                     ` Peter Zijlstra
2019-03-21 18:22               ` hpa
2019-03-22  5:54               ` Juergen Gross
2019-03-21 18:27             ` Peter Zijlstra
2019-03-21 18:28               ` Andy Lutomirski
2019-03-21 18:33                 ` Peter Zijlstra
2019-03-21 13:04   ` Steven Rostedt
2019-04-17  1:52 ` He Zhe

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