On 30/06/2019 05:29, David Taylor wrote:
> On 29/06/2019 20:10, Martin Gregorie wrote:
> []
>> I'll pass on this, thanks: like quite a lot of developers I do have a
>> personal support library or two and latish on a warm day like this has
>> been, I'm quite likely to omit stuff I shouldn't.
>>
>> One thing I forgot to mention is that all the times I quoted were for a
>> second or third compile.
>>
>> Unsurprisingly, repeated compile times on the T440 and dual Athlon were a
>> factor of 2-3 faster than the first compile. When I've looked in the past
>> 'top' has always made it obvious that this is due to Linux caching files
>> in RAM. I was a little surprised to see that this effect was entirely
>> absent for my Pi - obviously 500MB isn't enough memory to let file
>> caching have any significant effect on compilation speed for non-trivial
>> programs.
>
> Yes, that's one reason I bought the 4 GB model!  A pity I can't test for
> you, but my best estimate is that an RPi-4 would not disappoint.
>
remember that writing to a micro SD card is abominably slow. One should
probably regard them as EAROM. Cached writes possibly more important
than reads when compiling.

My Pi app needs fast scratch space to share between concurrently running
proceses (one writes, the other reads). It only has 512MB RAM, so I
configured a 1MB RAM drive on it.,

from /etc/fstab:

tmpfs /var/MiPiFi tmpfs nodev,nosuid,noexec,nodiratime,size=1M

That is a trick that might work if you know what tempoary filespace your
compiler uses and how big they are.


--
"In our post-modern world, climate science is not powerful because it is
true: it is true because it is powerful."

Lucas Bergkamp

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