From owner-svn-src-head@FreeBSD.ORG Tue Sep 2 16:36:50 2014 Return-Path: Delivered-To: svn-src-head@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 110B9340; Tue, 2 Sep 2014 16:36:50 +0000 (UTC) Received: from citadel.icyb.net.ua (citadel.icyb.net.ua [212.40.38.140]) by mx1.freebsd.org (Postfix) with ESMTP id 8FC531195; Tue, 2 Sep 2014 16:36:48 +0000 (UTC) Received: from porto.starpoint.kiev.ua (porto-e.starpoint.kiev.ua [212.40.38.100]) by citadel.icyb.net.ua (8.8.8p3/ICyb-2.3exp) with ESMTP id TAA29497; Tue, 02 Sep 2014 19:36:40 +0300 (EEST) (envelope-from avg@FreeBSD.org) Received: from localhost ([127.0.0.1]) by porto.starpoint.kiev.ua with esmtp (Exim 4.34 (FreeBSD)) id 1XOr4S-000CKM-J1; Tue, 02 Sep 2014 19:36:40 +0300 Message-ID: <5405F1F3.1@FreeBSD.org> Date: Tue, 02 Sep 2014 19:36:03 +0300 From: Andriy Gapon User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: John Baldwin , Peter Wemm , Steven Hartland Subject: Re: svn commit: r270759 - in head/sys: cddl/compat/opensolaris/kern cddl/compat/opensolaris/sys cddl/contrib/opensolaris/uts/common/fs/zfs vm References: <201408281950.s7SJo90I047213@svn.freebsd.org> <39211177.i8nn9sHiCx@overcee.wemm.org> <201409021201.15967.jhb@freebsd.org> In-Reply-To: <201409021201.15967.jhb@freebsd.org> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: src-committers@FreeBSD.org, Alan Cox , svn-src-all@FreeBSD.org, Dmitry Morozovsky , "Matthew D. Fuller" , svn-src-head@FreeBSD.org X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 02 Sep 2014 16:36:50 -0000 on 02/09/2014 19:01 John Baldwin said the following: > I know Steven has since committed a fix, but if there are still concerns, I > think it would be best to not just revert this entirely but to spend some time > fixing the remaining issues. Clearly this issue affects a lot of users and > the earlier fixes to pagedaemon were not sufficient to fix their issues alone. I am not sure that that is the case. I could have very well missed an evidence of that, but then I'd appreciate a pointer or two to such reports. I am certainly sure that a large number of reports about "ZFS vs swapping" issue appeared after the pagedaemon problem was introduced. I have also missed any "theoretical" justification for the patch. That is, an explanation of how the patch interacts with the pagedaemon and improves things. The empirical evidence could be insufficient, because it's easy to tilt the balance such that the ARC gives in too easily. But people who were affected by the opposite problem could be different from people who would be affected by the new problem, because of differences in system characteristics such as amount of RAM, workload patterns, working set sizes, etc. Having said that, I do not ask for the changes to be reverted, but I'll probably get back after I have sufficient time to look at the patch and also to test its effect on my systems. This might not be very soon though. P.S. I think that there was no technical reason to initialize the newly introduced parameters via SYSINIT mechanism. I think that the initialization could be just done in arc_init. And the newly added kmem_foo() functions probably do not belong in cddl/compat/opensolaris as Solaris / illumos does not have those functions. I think that in this case e.g. vm_cnt.v_free_target can just be used directly by the FreeBSD-specific ARC code. -- Andriy Gapon