Messages in this thread | | | Date | Mon, 17 Nov 2008 13:31:37 -0800 | From | Andrew Morton <> | Subject | Re: Large stack usage in fs code (especially for PPC64) |
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On Mon, 17 Nov 2008 13:23:23 -0800 (PST) Linus Torvalds <torvalds@linux-foundation.org> wrote:
> > > On Mon, 17 Nov 2008, Andrew Morton wrote: > > > > Far be it from me to apportion blame, but THIS IS ALL LINUS'S FAULT!!!!! :) > > > > I fixed this six years ago. See http://lkml.org/lkml/2002/6/17/68 > > Btw, in that thread I also said: > > "If we have 64kB pages, such architectures will have to have a bigger > kernel stack. Which they will have, simply by virtue of having the very > same bigger page. So that problem kind of solves itself." > > and that may still be the "right" solution - if somebody is so insane that > they want 64kB pages, then they might as well have a 64kB kernel stack as > well.
I'd have thought so, but I'm sure we're about to hear how important an optimisation the smaller stacks are ;)
> Trust me, the kernel stack isn't where you blow your memory with a 64kB > page. You blow all your memory on the memory fragmentation of your page > cache. I did the stats for the kernel source tree a long time ago, and I > think you wasted something like 4GB of RAM with a 64kB page size. >
Yup. That being said, the younger me did assert that "this is a neater implementation anyway". If we can implement those loops without needing those on-stack temporary arrays then things probably are better overall.
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