After update to r357104 build of poudriere jail fails with 'out of swap space'

[Cy Schubert]

In message <202001261745.00QHjkuW044006 at gndrsh.dnsmgr.net>, "Rodney W. 
Grimes"
writes:
> > In message <20200125233116.GA49916 at troutmask.apl.washington.edu>, Steve 
> > Kargl w
> > rites:
> > > On Sat, Jan 25, 2020 at 02:09:29PM -0800, Cy Schubert wrote:
> > > > On January 25, 2020 1:52:03 PM PST, Steve Kargl <sgk at troutmask.apl.wash
> ingt
> > > on.edu> wrote:
> > > > >On Sat, Jan 25, 2020 at 01:41:16PM -0800, Cy Schubert wrote:
> > > > >> 
> > > > >> It's not just poudeiere. Standard port builds of chromium, rust
> > > > >> and thunderbird also fail on my machines with less than 8 GB.
> > > > >>
> > > > >
> > > > >Interesting.  I routinely build chromium, rust, firefox,
> > > > >llvm and few other resource-hunger ports on a i386-freebsd
> > > > >laptop with 3.4 GB available memory.  This is done with
> > > > >chrome running with a few tabs swallowing a 1-1.5 GB of
> > > > >memory.  No issues.  
> > > > 
> > > > Number of threads makes a difference too. How many core/threads does yo
> ur l
> > > aptop have?
> > >
> > > 2 cores.
> > 
> > This is why.
> > 
> > >
> > > > Reducing number of concurrent threads allowed my builds to complete
> > > > on the 5 GB machine. My build machines have 4 cores, 1 thread per
> > > > core. Reducing concurrent threads circumvented the issue. 
> > >
> > > I use portmaster, and AFIACT, it uses 'make -j 2' for the build.
> > > Laptop isn't doing too much, but an update and browsing.  It does
> > > take a long time especially if building llvm is required.
> > 
> > I use portmaster as well (for quick incidental builds). It uses 
> > MAKE_JOBS_NUMBER=4 (which is equivalent to make -j 4). I suppose machines 
> > with not enough memory to support their cores with certain builds might 
> > have a better chance of having this problem.
> > 
> > MAKE_JOBS_NUMBER_LIMIT to limit a 4 core machine with less than 2 GB per 
> > core might be an option. Looking at it this way, instead of an extra 3 GB, 
> > the extra 60% more memory in the other machine makes a big difference. A 
> > rule of thumb would probably be, have ~ 2 GB RAM for every core or thread 
> > when doing large parallel builds.
>
> Perhaps we need to redo some boot time calculations, for one the
> ZFS arch cache, IMHO, is just silly at a fixed percent of total
> memory.  A high percentage at that.
>
> One idea based on what you just said might be:
>
> percore_memory_reserve = 2G (Your number, I personally would use 1G here)
> arc_max = MAX(memory size - (Cores * percore_memory_reserve), 512mb)
>
> I think that simple change would go a long ways to cutting down the
> number of OOM reports we see.  ALSO IMHO there should be a way for
> sub systems to easily tell zfs they are memory pigs too and need to
> share the space.  Ie, bhyve is horrible if you do not tune zfs arc
> based on how much memory your using up for VM's.
>
> Another formulation might be
> percore_memory_reserve = alpha * memory_zire / cores
>
> Alpha most likely falling in the 0.25 to 0.5 range, I think this one
> would have better scalability, would need to run some numbers.
> Probably needs to become non linear above some core count.

Setting a lower arc_max at boot is unlikely to help. Rust was building on 
the 8 GB and 5 GB 4 core machines last night. It completed successfully on 
the 8 GB machine, while using 12 MB of swap. ARC was at 1307 MB.

On the 5 GB 4 core machine the rust build died of OOM. 328 KB swap was 
used. ARC was reported at 941 MB. arc_min on this machine is 489.2 MB.


-- 
Cheers,
Cy Schubert <Cy.Schubert at cschubert.com>
FreeBSD UNIX:  <cy at FreeBSD.org>   Web:  http://www.FreeBSD.org

	The need of the many outweighs the greed of the few.