[PATCH 5/6] riscv: allow kmalloc() caches aligned to the smallest value

[Catalin Marinas]

On Tue, May 30, 2023 at 11:34:06AM +0100, Conor Dooley wrote:
> On Tue, May 30, 2023 at 10:59:41AM +0100, Catalin Marinas wrote:
> > On Mon, May 29, 2023 at 12:17:46PM +0100, Conor Dooley wrote:
> > > On Sat, May 27, 2023 at 12:59:57AM +0800, Jisheng Zhang wrote:
> > > > After this patch, a simple test of booting to a small buildroot rootfs
> > > > on qemu shows:
> > > > 
> > > > kmalloc-96           5041    5041     96  ...
> > > > kmalloc-64           9606    9606     64  ...
> > > > kmalloc-32           5128    5128     32  ...
> > > > kmalloc-16           7682    7682     16  ...
> > > > kmalloc-8           10246   10246      8  ...
> > > > 
> > > > So we save about 1268KB memory. The saving will be much larger in normal
> > > > OS env on real HW platforms.
> > > > 
> > > > [1] Link: https://lore.kernel.org/linux-arm-kernel/20230524171904.3967031-1-catalin.marinas@arm.com/
> 
> While I think of it, Link: goes at the start of the line, the [1] should
> go at the end (although I don't think you actually reference the link
> anywhere in the text & it'll probably not be particularly relevant if a
> subsequent revision of that patchset is applied.

I plan to post at least one more. I'd suggest the risc-v patchset to
only go in once my series landed.

> > > > Signed-off-by: Jisheng Zhang <jszhang at kernel.org>
> > > 
> > > Fails to build chief, with loads of:
> > > linux/dma-mapping.h:546:19: error: redefinition of 'dma_get_cache_alignment'
> > > 
> > > And for 32-bit there's also a rake of:
> > > include/linux/slab.h:239:9: warning: 'ARCH_KMALLOC_MINALIGN' macro redefined [-Wmacro-redefined]
> > > 
> > > At the very least, reproducable with rv32_defconfig.
> > 
> > Have you this it on top of the KMALLOC_MINALIGN preparation series?
> > 
> > https://lore.kernel.org/r/20230524171904.3967031-1-catalin.marinas@arm.com/
> 
> Oh, no. Thanks for pointing that out.
> Our automation stuff only uses what is in riscv/{for-next,master,fixes}.
> Unless my reading comprehension is particularly bad of late it was
> non-obvious that this depended on something that had not yet been
> applied - it sounded like your series had already been merged last year.

Yeah, it was only obvious to me since it was my series ;).

-- 
Catalin