On 20/06/2018 02:59, Jeremy Chadwick wrote: > In short (and nebulous as hell; sorry, I cannot be more specific given > the nature of the problem): there have been changes about ZFS's memory > allocation/releasing decision-making scheme compared to ZFS on "older" > FreeBSD (i.e. earlier 11.x, and definitely 10.x and 9.x).
I would say the issues started with 10.x, I never had memory issues using 9.x with ZFS. I first had all ram marked wired when testing 10.1. > Recommendations like "limit your ARC" are nothing new in FreeBSD, but > are still ridiculous kludges: tech-lists' system clearly has 105GB MRU > (MRU = most recently used) in ARC, meaning there is memory that can be > released back to the rest of the OS for general use (re: memory > contention/pressure situation), but the OS is choosing to use swap > instead, eventually exhausting it. That logic sounds broken, IMO. (And > yes I did notice the size of bhyve process) This review is aiming to fix this - https://reviews.freebsd.org/D7538 I have been running the patch on stable/11 and after eight days uptime I still have zero swap in use, I can't recall a time in the last few years that I have had no swap usage past the first hour or two uptime. As I have commented in that review, the issue I am seeing is that arc_max is not counted when testing max_wired, the two together can add up to more than the physical ram and wiring all physical ram can push ram used by processes out to swap. I know with 8G physical ram having over 7G wired is not recoverable. max_wired seems to default to 30% ram (5G with 16G ram) I have never seen this mentioned in any zfs tuning, it should be subtracted from physical ram when calculating arc_max. arc_max should never be greater than (kmem_size - max_wired - padding) -- FreeBSD - the place to B...Storing Data Shane Ambler _______________________________________________ freebsd-stable@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
