OpenZFS: kldload zfs.ko freezes on i386 4GB memory

[Cy Schubert]

In message <20201030220809.GG2033 at zxy.spb.ru>, Slawa Olhovchenkov writes:
> On Fri, Oct 30, 2020 at 01:53:10PM -0700, Cy Schubert wrote:
>
> > In message <20201030204622.GF2033 at zxy.spb.ru>, Slawa Olhovchenkov writes:
> > > On Thu, Oct 29, 2020 at 08:13:00PM -0700, Cy Schubert wrote:
> > >
> > > > In message <E1kWvLj-0000GY-Ic.qroxana-mail-ru at smtp29.i.mail.ru>, qroxan
> a 
> > > > writes
> > > > :
> > > > > 
> > > > > Hi,
> > > > >
> > > > > I have an old i386 machine running r364479. After upgrading to
> > > > > r367045, running kldload zfs.ko freezes the whole system.
> > > > >
> > > > > I also tried to replace the 4GB memory with another 2GB one
> > > > > and kldload zfs.ko works without freezing the machine.
> > > > 
> > > > ZFS ARC stresses memory. I've found a number of bad RAM chips over the 
> > > > years using ZFS.
> > > > 
> > > > The OpenZFS upgrade significantly changed how it manages ARC. It's like
> ly 
> > > > that prior to the OpenZFS upgrade your memory wasn't stressed to the po
> int 
> > > > of failure. You can try to mask the problem by reducing your RAM clock 
> rate
> > >  
> > > > or or increase one of the other latency settings in your BIOS. However,
>  
> > > > again, this only masks an already weak RAM chip.
> > >
> > > Sounds like performance drop and regression
> > 
> > How so. Please explain.
>
> More stresses memory usually refers to performance penalty.
> Usually way for better performance is reduce memory access.

The reason filesystems (UFS, ZFS, EXT4, etc.) cache is to avoid disk 
accesses. Nanoseconds vs milliseconds.


-- 
Cheers,
Cy Schubert <Cy.Schubert at cschubert.com>
FreeBSD UNIX:  <cy at FreeBSD.org>   Web:  https://FreeBSD.org
NTP:           <cy at nwtime.org>    Web:  https://nwtime.org

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