Residency profiles

[Simon Marlow]

It is documented!
https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/runtime_control.html#rts-flag--F%20%E2%9F%A8factor%E2%9F%A9

On Thu, 6 Dec 2018 at 16:21, Sebastian Graf <sgraf1337 at gmail.com> wrote:

> Hey,
>
> 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!
>
> Greetings
> Sebastian
>
> Am Do., 6. Dez. 2018 um 12:52 Uhr schrieb Simon Peyton Jones via ghc-devs <
> ghc-devs at haskell.org>:
>
>> |  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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>>
>
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