On Thursday, 15 January 2015 at 15:31:17 UTC, Peter Alexander
wrote:
On Thursday, 15 January 2015 at 15:24:55 UTC, Ola Fosheim
Grøstad wrote:
That would be nice, because then a precise garbage collector
could choose between local collection scans and global
collection scans.
I think something like this is part of the plan, but shared
semantics are still up in the air.
That sounds like a very important aspect of a plan to get fast GC
without completely changing the language and non-gc performance.
I've looked at bit at how to do a fast stop-the-thread GC.
Estimates on what the hardware supports (bandwidth and cache
performance) suggests that it is possible to get acceptable rates
for not-densely-linked heaps with some tweaks to semantics:
- shared-awareness in new-expressions to support local collection
- removing class-destructors
- locating traceable pointers to the same cachelines in class
instances (negative offsets is the easy solution)
Then you cn use a ache-optimized collector using batched
non-caching queues with prefetching to get bitmaps that fits in
1st level cache without wrecking the cache for other threads and
having collection dominated by cache misses.
