From: lkcl Date: Fri, 6 May 2022 10:53:16 +0000 (+0100) Subject: (no commit message) X-Git-Tag: opf_rfc_ls005_v1~2388 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=40b911aac28cbd7b180381c8404063b31c98aa9c;p=libreriscv.git --- diff --git a/openpower/sv/SimpleV_rationale.mdwn b/openpower/sv/SimpleV_rationale.mdwn index 4eee357e4..f3de0ae62 100644 --- a/openpower/sv/SimpleV_rationale.mdwn +++ b/openpower/sv/SimpleV_rationale.mdwn @@ -448,6 +448,21 @@ make *sequential* algorithm processing faster and faster because parallelising of algorithms is simply too difficult to master and always has been. Thus whilst DRAM has to go parallel (like RAID Striping) to keep up, CPUs are now at 8-way Multi-Issue 5 ghz clock rates and -are at an astonishing four levels of cache (L1 to L4). The amount -of wiring inside such CPUs is now measured in miles. +are at an astonishing four levels of cache (L1 to L4). + +It should therefore come as no surprise that attempts are being made +to move (distribute) processing closer to the DRAM Memory, firmly +on the *opposite* side of the main CPU's L1/2/3/4 Caches. However +the alarm bells ring here at the keyword "distributed", because by +moving the processing down next to the Memory, the speed of any +of the parallel Processing Elements has dropped +by almost two orders of magnitude, +the simplicity has for pure pragmatic reasons to drop by several +orders of magnitude. Things that the average "sequential algorithm" +programmer +takes for granted such as SMP, Cache Coherency, Virtual Memory, +spinlocks (atomic locking), all of these are either outright gone +or expected that the programmer shall explicitly contend with +(even if that programmer is the Compiler Developer). +