Date: Fri, 30 Oct 2020 15:34:10 -0700 From: Cy Schubert <Cy.Schubert@cschubert.com> To: Slawa Olhovchenkov <slw@zxy.spb.ru> Cc: Cy Schubert <Cy.Schubert@cschubert.com>, qroxana <qroxana@mail.ru>, freebsd-current@freebsd.org Subject: Re: OpenZFS: kldload zfs.ko freezes on i386 4GB memory Message-ID: <202010302234.09UMYA5d032018@slippy.cwsent.com> In-Reply-To: <20201030220809.GG2033@zxy.spb.ru> References: <E1kWvLj-0000GY-Ic.qroxana-mail-ru@smtp29.i.mail.ru> <202010300313.09U3D0KZ006216@slippy.cwsent.com> <20201030204622.GF2033@zxy.spb.ru> <202010302053.09UKrAXc031272@slippy.cwsent.com> <20201030220809.GG2033@zxy.spb.ru>
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In message <20201030220809.GG2033@zxy.spb.ru>, Slawa Olhovchenkov writes: > On Fri, Oct 30, 2020 at 01:53:10PM -0700, Cy Schubert wrote: > > > In message <20201030204622.GF2033@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@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@cschubert.com> FreeBSD UNIX: <cy@FreeBSD.org> Web: https://FreeBSD.org NTP: <cy@nwtime.org> Web: https://nwtime.org The need of the many outweighs the greed of the few.
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