linux-kernel - RE: [PATCH 3/6] pstore: Add persistent function tracing

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1339797308.25903.8.camel@gandalf.stny.rr.com>
Date:	Fri, 15 Jun 2012 17:55:08 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	"Luck, Tony" <tony.luck@...el.com>
Cc:	Anton Vorontsov <anton.vorontsov@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Kees Cook <keescook@...omium.org>,
	Colin Cross <ccross@...roid.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>, Arnd Bergmann <arnd@...db.de>,
	John Stultz <john.stultz@...aro.org>,
	Shuah Khan <shuahkhan@...il.com>,
	"arve@...roid.com" <arve@...roid.com>,
	Rebecca Schultz Zavin <rebecca@...roid.com>,
	Jesper Juhl <jj@...osbits.net>,
	Randy Dunlap <rdunlap@...otime.net>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Thomas Meyer <thomas@...3r.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Marco Stornelli <marco.stornelli@...il.com>,
	WANG Cong <xiyou.wangcong@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
	"patches@...aro.org" <patches@...aro.org>,
	"kernel-team@...roid.com" <kernel-team@...roid.com>
Subject: RE: [PATCH 3/6] pstore: Add persistent function tracing

On Fri, 2012-06-15 at 21:40 +0000, Luck, Tony wrote:
> > We store the log in a binary format and then decode it at read time.
> 
> What are the advantages of this compared to creating the human
> readable text and saving a blob of text?

With function tracing the impact to performance is tremendous. Just
recording two long words is a 130% hit to performance. Now multiply that
to recording strings.

> 
> What does this "binary format" look like?  Will it ever change?
> Remember that we may reboot to a different kernel - so we have
> to be really sure that the newer (or older) version can do the decode.

Good question.

-- Steve


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/