From owner-freebsd-current@freebsd.org Sat Oct 31 00:32:21 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 6118A45F654 for ; Sat, 31 Oct 2020 00:32:21 +0000 (UTC) (envelope-from mmacy@freebsd.org) Received: from smtp.freebsd.org (smtp.freebsd.org [IPv6:2610:1c1:1:606c::24b:4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4CNKrP1yQCz4fCk for ; Sat, 31 Oct 2020 00:32:21 +0000 (UTC) (envelope-from mmacy@freebsd.org) Received: from mail-lj1-f170.google.com (mail-lj1-f170.google.com [209.85.208.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) (Authenticated sender: mmacy) by smtp.freebsd.org (Postfix) with ESMTPSA id 2260D1361C for ; Sat, 31 Oct 2020 00:32:21 +0000 (UTC) (envelope-from mmacy@freebsd.org) Received: by mail-lj1-f170.google.com with SMTP id v19so3781982lji.5 for ; Fri, 30 Oct 2020 17:32:21 -0700 (PDT) X-Gm-Message-State: AOAM530clz7nLGi+Fc/u46ERTTAPptRmo4MeVePk8dx7MnbjuJ5cANhJ X4AfT7aA1CvSwTeuhrvpHg3IuznMtVldQKinG0c= X-Google-Smtp-Source: ABdhPJyNLvas9ClEB7RlynbqpZ7hmdG8Yj87IukcRvLi0cjSh/MBRIErvjcTc14/xD4kEP+atqCcEkJldA650SKtQoI= X-Received: by 2002:a2e:86c8:: with SMTP id n8mr2065289ljj.321.1604104339715; Fri, 30 Oct 2020 17:32:19 -0700 (PDT) MIME-Version: 1.0 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> In-Reply-To: From: Matthew Macy Date: Fri, 30 Oct 2020 17:32:08 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: OpenZFS: kldload zfs.ko freezes on i386 4GB memory To: freebsd-current Content-Type: text/plain; charset="UTF-8" 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 00:32:21 -0000 > > 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. Cheers. -M