Messages in this thread | | | Date | Wed, 27 Aug 2008 03:23:16 +0300 | From | Adrian Bunk <> | Subject | Re: [Bug #11342] Linux 2.6.27-rc3: kernel BUG at mm/vmalloc.c - bisected |
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On Tue, Aug 26, 2008 at 04:51:52PM -0700, Linus Torvalds wrote: > > > On Wed, 27 Aug 2008, Adrian Bunk wrote: > > > > > > We're much better off with a 1% code-size reduction than forcing big > > > stacks on people. The 4kB stack option is also a good way of saying "if it > > > works with this, then 8kB is certainly safe". > > > > You implicitely assume both would solve the same problem. > > I'm just saying that your logic doesn't hold water. > > If we can save kernel stack usage, then a 1% increase in kernel size is > more than worth it.
From some tests the size increase seems to become bigger for smaller kernels, but I don't have any really good data.
An interesting question is why most of our architectures for embedded devices only offer bigger stacks:
The only architectures offering a 4kB stacks option are: - m68knommu - sh - 32bit x86
The following architectures that are used in embedded devices always use 8kB stacks (or bigger) in your tree: - arm - avr32 - blackfin - cris - frv - h8300 - m32r - m68k - mips - mn10300 (has an #ifdef CONFIG_4KSTACKS but no kconfig option) - powerpc - xtensa
> > While 4kB stacks are something we anyway never got 100% working > > What? Don't be silly. > > Linux _historically_ always used 4kB stacks. > > No, they are likely not usable on x86-64, but dammit, they should be more > than usable on x86-32 still.
When did we get callpaths like like nfs+xfs+md+scsi reliably working with 4kB stacks on x86-32?
>... > Linus
cu Adrian
--
"Is there not promise of rain?" Ling Tan asked suddenly out of the darkness. There had been need of rain for many days. "Only a promise," Lao Er said. Pearl S. Buck - Dragon Seed
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