From owner-freebsd-current@freebsd.org Sat Oct 31 00:41:48 2020 Return-Path: Delivered-To: freebsd-current@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id AF9CB45FFFF for ; Sat, 31 Oct 2020 00:41:48 +0000 (UTC) (envelope-from cy.schubert@cschubert.com) Received: from smtp-out-so.shaw.ca (smtp-out-so.shaw.ca [64.59.136.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "Client", Issuer "CA" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4CNL3H6JGyz4fxZ for ; Sat, 31 Oct 2020 00:41:47 +0000 (UTC) (envelope-from cy.schubert@cschubert.com) Received: from spqr.komquats.com ([70.67.229.168]) by shaw.ca with ESMTPA id YexjkfHo1RAWfYexlkdVQ2; Fri, 30 Oct 2020 18:41:46 -0600 X-Authority-Analysis: v=2.4 cv=P9aEOgMu c=1 sm=1 tr=0 ts=5f9cb2ca a=7AlCcx2GqMg+lh9P3BclKA==:117 a=7AlCcx2GqMg+lh9P3BclKA==:17 a=xqWC_Br6kY4A:10 a=kj9zAlcOel0A:10 a=afefHYAZSVUA:10 a=YxBL1-UpAAAA:8 a=KawIFhhbAAAA:8 a=6I5d2MoRAAAA:8 a=EkcXrb_YAAAA:8 a=fm1SXRAjbU24maD8A3wA:9 a=CjuIK1q_8ugA:10 a=UJ0tAi3fqDAA:10 a=OJAZQCPpPQ8A:10 a=Ia-lj3WSrqcvXOmTRaiG:22 a=sDZbbUVwIjaXAAecbMhh:22 a=IjZwj45LgO3ly-622nXo:22 a=LK5xJRSDVpKd5WXXoEvA:22 Received: from slippy.cwsent.com (slippy [IPv6:fc00:1:1:1::5b]) by spqr.komquats.com (Postfix) with ESMTPS id 22A1FE93; Fri, 30 Oct 2020 17:41:43 -0700 (PDT) Received: from slippy (localhost [127.0.0.1]) by slippy.cwsent.com (8.16.1/8.16.1) with ESMTP id 09V0ffBL035185; Fri, 30 Oct 2020 17:41:41 -0700 (PDT) (envelope-from Cy.Schubert@cschubert.com) Message-Id: <202010310041.09V0ffBL035185@slippy.cwsent.com> X-Mailer: exmh version 2.9.0 11/07/2018 with nmh-1.7.1 Reply-to: Cy Schubert From: Cy Schubert X-os: FreeBSD X-Sender: cy@cwsent.com X-URL: http://www.cschubert.com/ To: Matthew Macy cc: Cy Schubert , Slawa Olhovchenkov , qroxana , freebsd-current Subject: Re: OpenZFS: kldload zfs.ko freezes on i386 4GB memory In-reply-to: References: <202010300313.09U3D0KZ006216@slippy.cwsent.com> <20201030204622.GF2033@zxy.spb.ru> <202010302053.09UKrAXc031272@slippy.cwsent.com> <20201030220809.GG2033@zxy.spb.ru> <202010302234.09UMYA5d032018@slippy.cwsent.com> <20201030224734.GH2033@zxy.spb.ru> <202010302300.09UN0t4A032372@slippy.cwsent.com> <20201030233138.GD34923@zxy.spb.ru> <202010302350.09UNoVcM033686@slippy.cwsent.com> Comments: In-reply-to Matthew Macy message dated "Fri, 30 Oct 2020 17:30:35 -0700." Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Fri, 30 Oct 2020 17:41:41 -0700 X-CMAE-Envelope: MS4xfKvdoiNwDKFKuX+HsdekYjfHtXCol16V41vbNGa5xAq+YM+Muokbr2yFvRfoNPVSTUsTsYUrO8g8pZAD8DR6cnPVZ7uk3gHDycD+rzacnkIaBX1x1aUq NsaYM3mCtbgeJYfHlBBLsQF7taE174Dx0qNVliaBaXeutw9ejrLNdJ5Dn4LIRl5U4VLUIuVNwKuKrHiMd0sI4d3/UBjr+CKd9GyBQgADhcm2cPKRFuw1Ew0b WNBFV+7sKNRYampayaRg8Fyx67qiHfxcmW3rVCNuy1l+HxiW2mydCgxHhHf3olGz X-Rspamd-Queue-Id: 4CNL3H6JGyz4fxZ X-Spamd-Bar: + X-Spamd-Result: default: False [1.09 / 15.00]; HAS_REPLYTO(0.00)[Cy.Schubert@cschubert.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; MV_CASE(0.50)[]; RCVD_TLS_LAST(0.00)[]; RCPT_COUNT_FIVE(0.00)[5]; RCVD_COUNT_THREE(0.00)[4]; TO_DN_ALL(0.00)[]; FREEMAIL_TO(0.00)[gmail.com]; RECEIVED_SPAMHAUS_PBL(0.00)[70.67.229.168:received]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; RCVD_IN_DNSWL_LOW(-0.10)[64.59.136.137:from]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:6327, ipnet:64.59.128.0/20, country:CA]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-0.90)[-0.899]; REPLYTO_EQ_FROM(0.00)[]; FROM_HAS_DN(0.00)[]; NEURAL_SPAM_SHORT(0.25)[0.249]; NEURAL_HAM_LONG(-1.06)[-1.064]; TAGGED_RCPT(0.00)[]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[cschubert.com: no valid DMARC record]; AUTH_NA(1.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; R_SPF_NA(0.00)[no SPF record]; FREEMAIL_CC(0.00)[cschubert.com,zxy.spb.ru,mail.ru,freebsd.org]; SUSPICIOUS_RECIPS(1.50)[]; MAILMAN_DEST(0.00)[freebsd-current] X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 31 Oct 2020 00:41:48 -0000 In message , Matthew Macy writes: > On Fri, Oct 30, 2020 at 4:50 PM Cy Schubert wrote > : > > > > In message <20201030233138.GD34923@zxy.spb.ru>, Slawa Olhovchenkov writes: > > > On Fri, Oct 30, 2020 at 04:00:55PM -0700, Cy Schubert wrote: > > > > > > > > > > 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 dis > k > > > > > > accesses. Nanoseconds vs milliseconds. > > > > > > > > > > I mean compared ZoL ZFS ARC vs old (BSD/Opensolaris/Illumos) ZFS ARC. > > > > > Any reaason to rise ARC hit rate in ZoL case? > > > > > > > > That's what hit rate is. It's a memory access instead of a disk access. > > > > That's what you want. > > > > > > Is ZoL ARC hit rate rise from FreeBSD ARC hit rate? > > > > We don't know that. You should be able to find out by running some tests > > that would populate your ARC and run the test again. I see that my > > -DNO_CLEAN buildworlds run faster, when I run them a second or third time > > after making a minor edit, than they did before. Thus I assume it uses > > memory more efficiently. By default it stores more metadata in ARC, 75% > > instead of IIRC 25% by default. > > > > Getting back to your original question. A more efficient ARC would exercise > > your memory more intensely because you are replacing disk reads with memory > > reads. And as I said before the old ZFS "found" weak RAM on three separate > > occasions in three different machines over the last ten years. You're > > advised to replace the marginal memory. > > Ryan has been able to reproduce this in a VM with 4GB, similarly a VM > with 2GB loads just fine. It would seem that 4GB triggers a bug in > limit handling. We're hoping that we can simply lower one of the > default limits on i386 and make the problem go away. > > Please don't shoot the messenger when I observe that, generally > speaking, i386 is considered a self supported platform due to ZFS > general inability to perform well with limited memory or KVA. Long > mode has been available on virtually all processors shipped since > 2006. Yes, I was able to use ZFS on a 2 GB Pentium-M (i386) laptop for many years. ZFS worked well with a little tuning on such a small machine. Last time I booted it was late last year or early this year. It's in a drawer right now. I'll try to pull it out this coming week to test it out. Serendipitous that I was thinking about pulling out that old laptop to test out the new ZFS just last week. -- Cheers, Cy Schubert FreeBSD UNIX: Web: https://FreeBSD.org NTP: Web: https://nwtime.org The need of the many outweighs the greed of the few.