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Date:   Tue, 30 May 2023 14:08:10 +0100
From:   Catalin Marinas <catalin.marinas@arm.com>
To:     Conor Dooley <conor.dooley@microchip.com>
Cc:     Jisheng Zhang <jszhang@kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/6] riscv: allow kmalloc() caches aligned to the
 smallest value
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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@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