Re: [PATCH 0/5] Rewrite Motorola MMU page-table layout

Michael Schmitz
2020-01-30T07:31:21Z

Peter,

Am 30.01.2020 um 08:31 schrieb Peter Zijlstra:
> On Thu, Jan 30, 2020 at 07:52:11AM +1300, Michael Schmitz wrote:
>> Peter,
>>
>> On Thu, Jan 30, 2020 at 12:54 AM Peter Zijlstra <peterz@infradead.org> wrote:
>>>
>>> On Wed, Jan 29, 2020 at 11:49:13AM +0100, John Paul Adrian Glaubitz wrote:
>>>
>>>>> [1] https://wiki.debian.org/M68k/QemuSystemM68k
>>>
>>> Now, if only debian would actually ship that :/
>>>
>>> AFAICT that emulates a q800 which is another 68040 and should thus not
>>> differ from ARAnyM.
>>>
>>> I'm fairly confident in the 040 bits, it's the 020/030 things that need
>>> coverage.
>>
>> I'll take a look - unless this eats up way more kernel memory for page
>> tables, it should still boot on my Falcon.
>
> It should actually be better in most cases I think, since we no longer
> require all 16 pte-tables to map consecutive (virtual) memory.

Not much difference:

total used free shared buffers cached
Mem: 10712 10120 592 0 1860 2276
-/+ buffers/cache: 5984 4728
Swap: 2097144 1552 2095592

vs. vanilla 5.5rc5:
total used free shared buffers cached
Mem: 10716 10104 612 0 1588 2544
-/+ buffers/cache: 5972 4744
Swap: 2097144 1296 2095848

By sheer coincidence, the boot with your patch series happened to run a
full filesystem check on the root filesystem, so I'd say it got a good
workout re: paging and swapping (even though it's just a paltry 4 GB).

Haven't tried any VM stress testing yet (not sure what to do for that;
it's been years since I tried that sort of stuff).

Cheers,

Michael