Le ven. 5 juin 2020 à 09:41, Linux User #330250
<linuxuser330...@gmx.net> a écrit :
> Because: why not use btrfs on a 64-Bit PowerPC, right?

Well, ZFS works fine on PPC64 (and PPC!) and 'someone' even
contributed AltiVec acceleration for the RAID-Z algorithms :-) [in all
fairness, I haven't tried ZFS Root on PPC64, only on x68-64 &
SPARC64].

On the subject of page size - 64 KiB makes a lot more sense than 4 KiB
when you have gigabytes of memory. The fact that x86-64 is stuck with
the page size of a 80386 with 4 MiB of RAM doesn't mean everyone
should be... And 64 KiB should gain traction on modern hardware, as
it's the default in e.g. RedHat for Arm64 (why RISC-V thinks 4 KiB is
OK for everyone I'll never understand, it's fine for small embedded
but not larger systems).

The PowerPC 970 only has 1024 entries in it's TLB IIRC, it's probably
quite useful to be able to map 64 MiB instead of 4 MiB without TLB
reloads... Broken software that can't work with non-4 KiB page size
should be fixed rather than forcing everyone to stay on the 80's idea
of memory usage. Most G5 owners probably maxed-out memory as it's dirt
cheap nowadays (I know I have the full 16 GiB), and those CPUs need
all the help they can get.

That being said - I'm not the one doing the work and it's probably
time-consuming to fix support for old hardware (which may or may not
be even capable to deal with it in the first place), so if the only
way to get proper support for old GPUs is to go back to 4 KiB page
size, so be it. I'd appreciate it if we kept both variant rather than
a full revert, though (if only for testing support isn't broken as it
was for a while last year).

Cordially,

-- 
Romain Dolbeau

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