> On May 13, 2019, at 11:26 AM, Eric Friedrich -X (efriedri - TRITON UK BIDCO
> LIMITED c/o Alter Domus (UK) Limited -OBO at Cisco) <[email protected]>
> wrote:
>
> Hi All-
> Looking for guidance on the best way to set the ram_cache.size parameter as
> TS seems to take it as only general suggestion.
>
> Should we assume a fixed ratio (like setting the size to 1/3rd the desired
> size)?
That seems pessimistic. It really depends on your use cases, in our setup, the
RAM cache stays pretty much static once it reaches “peak” (after 12h or so from
restart).
>
> Are there any options for getting allocated, yet not in-use buffers either
> free()’d or coalesced/split in place of new allocations?
>
If it’s a serious problem, like your usage pattern makes the RAM cache swing
dramatically on iobuffer sizes, you can turn off the ATS freelist. I would
definitely compile and/or run with jemalloc if you do this, and keep a close
eye on it. Under pressure, jemalloc likely perforce worse than the freelist
(still TBD), and there’s been at least some cases where it failed miserably
(mine :), but that still also needs more analysis / work.
— Leif
