Messages in this thread | | | Date | Wed, 11 Mar 2009 20:32:22 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 4/4] ring-buffer: only allocate buffers for online cpus |
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On Wed, 11 Mar 2009 22:37:24 -0400 Steven Rostedt <rostedt@goodmis.org> wrote:
> From: Steven Rostedt <srostedt@redhat.com> > > Impact: save on memory > > Currently, a ring buffer was allocated for each "possible_cpus". On > some systems, this is the same as NR_CPUS. Thus, if a system defined > NR_CPUS = 64 but it only had 1 CPU, we could have possibly 63 useless > ring buffers taking up space. With a default buffer of 3 megs, this > could be quite drastic. > > This patch changes the ring buffer code to only allocate ring buffers > for online CPUs. If a CPU goes off line, we do not free the buffer. > This is because the user may still have trace data in that buffer > that they would like to look at. > > Perhaps in the future we could add code to delete a ring buffer if > the CPU is offline and the ring buffer becomes empty. > > ... > > +#ifdef CONFIG_HOTPLUG > +#ifdef CONFIG_HOTPLUG > +#ifdef CONFIG_HOTPLUG > +#ifdef CONFIG_HOTPLUG > +#ifdef CONFIG_HOTPLUG
CONFIG_HOTPLUG_CPU
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