Residency profiles

Sebastian Graf sgraf1337 at
Thu Dec 6 16:21:17 UTC 2018


thanks, all! Measuring with `-A1M -F1` delivers much more reliable
residency numbers.
`-F` doesn't seem to be documented. From reading `rts/RtsFlags.c` and
`rts/sm/GC.c` I gather that it's the factor by which to multiply the number
of live bytes by to get the new old gen size?
So effectively, the old gen will 'overflow' on every minor GC, neat!


Am Do., 6. Dez. 2018 um 12:52 Uhr schrieb Simon Peyton Jones via ghc-devs <
ghc-devs at>:

> |  Right. A parameter for fixing the nursery size would be easy to
> implement,
> |  I think. Just a new flag, then in GC.c:resize_nursery() use the flag as
> the
> |  nursery size.
> Super!  That would be v useful.
> |  "Max. residency" is really hard to measure (need to do very frequent
> GCs),
> |  perhaps a better question to ask is "residency when the program is in
> state
> |  S".
> Actually, Sebastian simply wants to see an accurate, reproducible
> residency profile, and doing frequent GCs might well be an acceptable
> cost.
> Simon
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