On Sunday, 29 December 2013 at 20:36:27 UTC, Walter Bright wrote:
I'll reiterate that the GC will NEVER EVER pause your program
unless you are actually calling the GC to allocate memory. A
loop that does not GC allocate WILL NEVER PAUSE.
That's fine, except when you have real-time threads.
So unless you use non-temporal load/save in your GC traversal
(e.g. on x86 you have SSE instructions that bypass the cache),
your GC might trash the cache for other cores that run real-time
threads which are initiated as call-backs from the OS.
These callbacks might happen 120+ times per seconds and your
runtime cannot control those, they have the highest user-level
priority.
Granted, the latest CPUs have a fair amount of level 3 cache, and
the most expensive ones might have a big level 4 cache, but I
still think it is a concern. Level 1 and 2 caches are small:
64KB/128KB.
