From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Serge E. Hallyn" Subject: Re: [PATCH 1/1] fix compile with CONFIG_CHECKPOINT_DEBUG=n Date: Fri, 23 Oct 2009 14:46:41 -0500 Message-ID: <20091023194641.GA29761@us.ibm.com> References: <20091022143238.GA31778@us.ibm.com> <4AE1FB87.4050305@librato.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <4AE1FB87.4050305-RdfvBDnrOixBDgjK7y7TUQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Oren Laadan Cc: Linux Containers List-Id: containers.vger.kernel.org Quoting Oren Laadan (orenl-RdfvBDnrOixBDgjK7y7TUQ@public.gmane.org): > > > Serge E. Hallyn wrote: > > On the one hand, compiling without checkpoing debug saves a > > lot of kernel size: > > > > with debug: > > -rwxrwxr-x 1 hallyn hallyn 62391508 Oct 21 22:08 vmlinux > > without debug: > > -rwxrwxr-x 1 hallyn hallyn 62298077 Oct 21 22:33 vmlinux > > > > OTOH the need for this patch just proves my point that we don't > > want any more config options than we need (especially no > > CONFIG_CHECKPOINT_LOGGING in addition to _DEBUG). > > > > So that begs the question - is there something we can do to > > avoid having to recompile the kernel to turn on debugging, > > but not take up 100k of space in vmlinux? Maybe get rid of > > the ckpt_debugs altogether and instead provide pre-written > > kprobe sets to turn on debugging at specific places? > > What is the reason for the increase - the strings ? the extra > inlined code ? the passing of variables to printed ? Half and half :) Pulling out the 'current->pid' and task_pid_nr arguments in _ckpt_debug to printk, but keeping the __func__ and __LINE__, halves the overhead of CONFIG_CHECKPOINT_DEBUG from 78190 to 39809 bytes. -serge