On 4/21/22, Alexander Leidinger <alexan...@leidinger.net> wrote:I tried nocache on a system with a lot of jails which use nullfs, which showed very slow behavior in the daily periodic runs (12h runs in the night after boot, 24h or more in subsequent nights). Now the first nightly run after boot was finished after 4h.What is the benefit of not disabling the cache in nullfs? I would expect zfs (or ufs) to cache the (meta)data anyway.does the poor performance show up with https://people.freebsd.org/~mjg/vnlru_free_pick.diff ?
I would like to have all the 22 jails run the periodic scripts a second night in a row before trying this.
if the long runs are still there, can you get some profiling from it? sysctl -a before and after would be a start. My guess is that you are the vnode limit and bumping into the 1 second sleep.
That would explain the behavior I see since I added the last jail which seems to have crossed a threshold which triggers the slow behavior.
Current status (with the 112 nullfs mounts with nocache): kern.maxvnodes: 10485760 kern.numvnodes: 3791064 kern.freevnodes: 3613694 kern.cache.stats.heldvnodes: 151707 kern.vnodes_created: 260288639The maxvnodes value is already increased by 10 times compared to the default value on this system.
Bye, Alexander. -- http://www.Leidinger.net alexan...@leidinger.net: PGP 0x8F31830F9F2772BF http://www.FreeBSD.org netch...@freebsd.org : PGP 0x8F31830F9F2772BF
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