Re: Memory upgrade

On 10/14/24 15:49, Stuart Henderson wrote:
> On 2024-10-14, Christian Schulte <cs@schulte.it> wrote:
>> On 10/14/24 10:33, Stuart Henderson wrote:
>>> On 2024-10-12, Christian Schulte <cs@schulte.it> wrote:
>>>> Take i386. Compile it with something -march=i686 or pentiumpro by
>>>> default. That's it. Add support for the various PAE MMU options.
>>>
>>> "That's it". "Add support for". Do you really think it's a thing simple
>>> enough to sum up in a few words?
>>
>> That "add support for the various PAE MMU options" is not just a few
>> words, of course. Waste of time? Maybe. If 4GB is not enough upgrade the
>> hardware and run amd64.
>>
>>>
>>> Last time steps in this direction were attempted, i386 was subtly broken
>>> on AMD CPUs for months.
>>>
>>>> My current daily is a Lenovo x240 with 8GB of RAM running amd64
>>>> and this thing is swapping like mad. Throw a 32 bit OS at it supporting
>>>> those 8GB of RAM and go for it. Why would anyone throw away such a
>>>> machine, just because a 64 bit OS hits its boundaries, when a 32 bit OS
>>>> would not?
>>>
>>> And then ASLR would be seriously limited, because of the low amount of
>>> address space per process. And it's hard to predict how usable it would
>>> actually be, especially on an OS that uses PIE widely, due to the lower
>>> number of registers.
>>>
>>
>> Running i386 on a CPU supporting amd64 makes no sense, I admit.
>
> i386 snapshot packages would take a _lot_ longer to build if I had to do
> that on hardware which does not support amd64...
>
>> Last
>> time running i386 is more than a decade ago. Step one for me currently is:
>>
>> 1. Am I the only one experiencing this 8GB of RAM is not enough for an
>> amd64 laptop just because Firefox with a few open tabs and Thunderbird
>> running in parallel will make it swap? The answer seems to be yes. Quite
>> confused right now. I upgraded RAM from 4GB to
>>
>> spdmem0 at iic0 addr 0x50: 8GB DDR3 SDRAM PC3-12800 SO-DIMM
>>
>> two weeks ago. That's why the subject caught my attention. Still swaps
>> but cannot add more than 8GB to that machine. What now? Have some fun
>> with KiCAD? No - buy a new laptop. How on earth can 8GB physical RAM not
>> be enough for browsing the web and doing email? I must be doing
>> something seriously wrong.
>
> Running Firefox and Thunderbird simultaneously is probably asking
> a lot from 8GB.
>
> I wouldn't consider less than 16GB for a laptop now. For that,
> Thinkpad-wise you'll need at least X250 (if you can find one where
> the machine hasn't been destroyed with extreme prejudice due to the
> absolutely terrible clunkpad) or more likely X260, if not one of the
> newer ones - X240 is single slot and I don't think Intel released a
> MRC for the generation of CPUs used in X240 that supports 16GB DIMMs.
> (https://en.wikipedia.org/wiki/Memory_Reference_Code)
>

I'd first like to find out why this system is swapping at all. I managed
to issue top(1) this time, when the system was locked up due to
swapping. Here are the readings I could capture - issuing top(1) took
nearly a minute to come up:

load averages: 0.04, 0.35, 0.54

x500.schulte.it 09:44:01
70 processes: 68 idle, 2 on processor

up 4 days 01:17:15
CPU0 states: 9.0% user, 0.0% nice, 3.2% sys, 0.2% spin, 1.0% intr,
86.6% idle
CPU2 states: 6.9% user, 0.0% nice, 3.5% sys, 0.2% spin, 0.0% intr,
89.4% idle
Memory: Real: 2867M/4129M act/tot Free: 3483M Cache: 277M Swap: 718M/4230M

That's more than half a GB of swapped out memory, although there are
nearly 4GB of memory reported as free. So why does it start swapping,
locking up the whole system from time to time, although there is nearly
4GB of free unwired RAM available?

--
Christian