Re: Parallel Forth on a 44 core machine

On Sun, 18 Aug 2024 9:28:09 +0000, minforth wrote:

Impressive! A PCIe NVMe drive will be a boost, but don't expect
too much, when you already have so much RAM. And electric power. ;-)

I tried a RAM drive (from AMD), but it has a throughput of only 50MB/s,
10x slower than the SATA 6GBs connected Samsung SSD (500MB/s). I am a
bit puzzled why that is so devastatingly slow.

My experiments with parallel threads were a bit sobering. You
really need rather isolated subprocesses that require little
synchronisation.

Yes, that is Amdahl's law. We constantly struggled with that
for tForth. Fine-grained parallelism never gave us good results.

Otherwise the slowest process plus additional
syncing costs can eat up all the expected benefits. Nothing new.

A new (to me) thing was that processes slow down enormously from
accessing shared global variables (depending on their physical
location), even when no locks are needed/used. For iSPICE such
variables are in OS managed shared memory (aka the swap file)
and are used very infrequently.
-marcel