Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [GIT PULL] arm64 updates for 4.4 | Date | Sat, 07 Nov 2015 20:23:24 +0100 |
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On Saturday 07 November 2015 11:56:44 Hans Ulli Kroll wrote: > On Fri, 6 Nov 2015, Arnd Bergmann wrote: > > On Friday 06 November 2015 16:04:08 Catalin Marinas wrote: > > > On Fri, Nov 06, 2015 at 10:57:58AM +0100, Arnd Bergmann wrote: > > > > On Thursday 05 November 2015 18:27:18 Catalin Marinas wrote: > > > > > On Wed, Nov 04, 2015 at 02:55:01PM -0800, Linus Torvalds wrote: > > > > > > On Wed, Nov 4, 2015 at 10:25 AM, Catalin Marinas <catalin.marinas@arm.com> wrote: > > > > > > It's good for single-process loads - if you do a lot of big fortran > > > > > > jobs, or a lot of big database loads, and nothing else, you're fine. > > > > > > > > > > These are some of the arguments from the server camp: specific > > > > > workloads. > > > > > > > > I think (a little overgeneralized), you want 4KB pages for any file > > > > based mappings, > > > > > > In general, yes, but if the main/only workload on your server is mapping > > > large db files, the memory usage cost may be amortised. > > > > This will still only do you good for a database that is read into memory > > once and not written much, and at that point you can as well use hugepages. > > > > The problems for using 64kb page cache on file mappings are > > > > - while you normally want some readahead, the larger pages also result > > in read-behind, so you have to actually transfer data from disk into > > RAM without ever accessing it. > > > > - When you write the data, you have to write the full 64K page because > > that is the granularity of your dirty bit tracking. > > > > So even if you don't care at all about memory consumption, you are > > still transferring several times more data to and from your drives. > > As mentioned that can be a win on some storage devices, but usually > > it's a loss. > > > > there is also a maybe a bigger problem. > I know this from my Zyxel NAS540, this thing is build around the Mindspeed > Comcerto 2000 SoC > > Zyxel is currently rolling back to support 4k page sizeses in upcommig > 5.10 firmware release, because Minspeed did some stupid thing : > > It's not possible to use some standard ARMv7 toolchain and build your > own/needed userspace tools. > > And this in change which causes the pain > > diff --git a/arch/arm/include/asm/elf.h b/arch/arm/include/asm/elf.h > -#define ELF_EXEC_PAGESIZE 4096 > +#define ELF_EXEC_PAGESIZE (PAGE_SIZE)
In ARM32 binutils, ELF_MAXPAGESIZE was changed last year to 64KB, so binutils-2.25 or higher should support this by default, as long as you recompile all user binaries.
> The SoC is mostly build from off the shelf IP's > SATA, NAND, SPI and so on > The only thing which is completly braindead is MAC > It's using some kind of VLAN tagging to support tree ports, > only one descriptor chain for all three interfaces.
You mean they used 64KB logical page sizes to work around a broken ethernet MAC?
Arnd
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