On Thu, 26 Jun 2014 16:32:15 -0700 "Luis R. Rodriguez" <mcg...@suse.com> wrote:
> On Thu, Jun 26, 2014 at 4:20 PM, Andrew Morton > <a...@linux-foundation.org> wrote: > > On Fri, 27 Jun 2014 01:16:30 +0200 "Luis R. Rodriguez" <mcg...@suse.com> > > wrote: > > > >> > > Another note -- since this option depends on SMP and !BASE_SMALL > >> > > technically > >> > > num_possible_cpus() won't ever return something smaller than or equal > >> > > to 1 > >> > > but because of the default values chosen the -1 on the compuation does > >> > > affect > >> > > whether or not this will trigger on > 64 CPUs or >= 64 CPUs, keeping > >> > > the > >> > > -1 means we require > 64 CPUs. > >> > > >> > hm, that sounds like more complexity. > >> > > >> > > This all can be changed however we like but the language and explained > >> > > logic > >> > > would just need to be changed. > >> > > >> > Let's start out simple. What's wrong with doing > >> > > >> > log buf len = max(__LOG_BUF_LEN, nr_possible_cpus * per-cpu log buf > >> > len) > >> > >> Sure, you already took in the patch series though so how would you like to > >> handle a respin, you just drop the last patch and we respin it? > > > > A fresh patch would suit. That's if you think it is a reasonable > > approach - you've thought about this stuff more than I have! > > The way its implemented now makes more technical sense, in short it > assumes the first boot (and CPU) gets the full default kernel ring > buffer size, the extra size is for the gibberish that each extra CPU > is expected to spew out in the worst case. What you propose makes the > explanation simpler and easier to understand but sends the wrong > message about exactly how the growth of the kernel ring buffer is > expected scale with the addition of more CPUs. OK, it's finally starting to sink in. The model for the kernel-wide printk output is "a great pile of CPU-independent stuff plus a certain amount of per-cpu stuff". And the code at present attempts to follow that model. Yes? I'm rather internet-challenged at present - please let me take another look at the patch on Monday. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
