Re: How to explain high memory consumption of a jail after all large processed in it have finished?

Am 2024-09-12 20:45, schrieb Yuri:
> I noticed that when the port lang/rust is building in the poudriere 
> jail the memory consumption of the host system remains high all the way 
> into the packaging phase when the pkg-static process is the only active 
> process and it consumes a very little memory.
> 
> 
> During build a lot of memory is consumed, which is understandable. The 
> system remains at ~500MB of free memory through the build process, 
> according to top(1).
> 
> 
> But once the build is finished, poudriere goes into the "packaging" 
> phase which only runs a small pkg-static process that compresses the 
> built files. pkg-static is the only active process in the poudriere 
> jail.
> 
> 
> What looks strange to me is that the host system's memory consumption 
> remains high through the "packaging" phase which itself is low in 
> memory, and only goes down when the jail is destroyed.
> 
> 
> How to explain the high memory consumption of a jail after all large 
> presses have finished?

That's not enough information to answer it, but my crystal ball hints at 
an interaction between nullfs/zfs. Most probably it's not the 
jail-teardown itself which frees the mem, but the unmounting of some 
nullfs mounts.

Depending on the version of FreeBSD you are using, you could try if 
"sysctl vfs.nullfs.cache_vnodes=0" changes this behavior (I'm not saying 
that this is a "solution" to the "issue" you see, I simply say this may 
change the behavior).

Bye,
Alexander.

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