From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Paris Subject: Re: [PATCH v3] audit: Turn off TIF_SYSCALL_AUDIT when there are no rules Date: Tue, 18 Feb 2014 15:17:45 -0500 Message-ID: <1392754665.2165.33.camel@flatline.rdu.redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-audit-bounces@redhat.com Errors-To: linux-audit-bounces@redhat.com To: Andy Lutomirski Cc: linux-audit@redhat.com, Andi Kleen , linux-kernel@vger.kernel.org, Oleg Nesterov List-Id: linux-audit@redhat.com On Sat, 2014-02-08 at 13:06 -0800, Andy Lutomirski wrote: > This toggles TIF_SYSCALL_AUDIT as needed when rules change instead > of leaving it set whenever rules might be set in the future. This > reduces syscall latency from >60ns to closer to 40ns on my laptop. Al also politely reminded me it might be wise to get some perf data about where exactly we are spending out time. I don't know squat about perf, but Linus always tells me to do: perf record -g -e cycles:pp -F 25000 $YOURTEST perf report -s symbol (the "-s symbol" is so that you don't get separate data for the different processes that are part of the kernel build - you'll just want "general kernel data"), and on one of the kernel symbols just select it and do "Zoom into kernel DSO". You should see something like this: