From owner-freebsd-mips@FreeBSD.ORG Mon Aug 20 15:54:48 2012 Return-Path: Delivered-To: mips@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id A6494106585D for ; Mon, 20 Aug 2012 15:54:48 +0000 (UTC) (envelope-from alc@rice.edu) Received: from mh10.mail.rice.edu (mh10.mail.rice.edu [128.42.201.30]) by mx1.freebsd.org (Postfix) with ESMTP id 72EBD8FC08 for ; Mon, 20 Aug 2012 15:54:47 +0000 (UTC) Received: from mh10.mail.rice.edu (localhost.localdomain [127.0.0.1]) by mh10.mail.rice.edu (Postfix) with ESMTP id 08661604CE; Mon, 20 Aug 2012 10:54:47 -0500 (CDT) Received: from mh10.mail.rice.edu (localhost.localdomain [127.0.0.1]) by mh10.mail.rice.edu (Postfix) with ESMTP id 073F9604CA; Mon, 20 Aug 2012 10:54:47 -0500 (CDT) X-Virus-Scanned: by amavis-2.7.0 at mh10.mail.rice.edu, auth channel Received: from mh10.mail.rice.edu ([127.0.0.1]) by mh10.mail.rice.edu (mh10.mail.rice.edu [127.0.0.1]) (amavis, port 10026) with ESMTP id 7mX0oMSi1cJt; Mon, 20 Aug 2012 10:54:46 -0500 (CDT) Received: from adsl-216-63-78-18.dsl.hstntx.swbell.net (adsl-216-63-78-18.dsl.hstntx.swbell.net [216.63.78.18]) (using TLSv1 with cipher RC4-MD5 (128/128 bits)) (No client certificate requested) (Authenticated sender: alc) by mh10.mail.rice.edu (Postfix) with ESMTPSA id 8274E6047D; Mon, 20 Aug 2012 10:54:46 -0500 (CDT) Message-ID: <50325DC3.3090201@rice.edu> Date: Mon, 20 Aug 2012 10:54:43 -0500 From: Alan Cox User-Agent: Mozilla/5.0 (X11; FreeBSD i386; rv:8.0) Gecko/20111113 Thunderbird/8.0 MIME-Version: 1.0 To: "Jayachandran C." References: <50228F5C.1000408@rice.edu> <50269AD4.9050804@rice.edu> <5029635A.4050209@rice.edu> <502D2271.6080105@rice.edu> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: mips@freebsd.org Subject: Re: mips pmap patch X-BeenThere: freebsd-mips@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Porting FreeBSD to MIPS List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 20 Aug 2012 15:54:48 -0000 On 08/20/2012 05:36, Jayachandran C. wrote: > On Thu, Aug 16, 2012 at 10:10 PM, Alan Cox wrote: >> On 08/15/2012 17:21, Jayachandran C. wrote: >>> On Tue, Aug 14, 2012 at 1:58 AM, Alan Cox wrote: >>>> On 08/13/2012 11:37, Jayachandran C. wrote: > [...] >>>>> I could not test for more than an hour on 32-bit due to another >>>>> problem (freelist 1 containing direct-mapped pages runs out of pages >>>>> after about an hour of compile test). This issue has been there for a >>>>> long time, I am planning to look at it when I get a chance. >>>>> >>>> What exactly happens? panic? deadlock? >>> The build slows down to a crawl and hangs when it runs out of pages in >>> the freelist. >> >> I'd like to see the output of "sysctl vm.phys_segs" and "sysctl >> vm.phys_free" from this machine. Even better would be running "sysctl >> vm.phys_free" every 60 seconds during the buildworld. Finally, I'd like to >> know whether or not either "ps" or "top" shows any threads blocked on the >> "swwrt" wait channel once things slow to a crawl. > I spent some time looking at this issue. I use a very large kernel > image with built-in root filesystem, and this takes about 120 MB out > of the direct mapped area. The remaining pages (~64 MB) are not enough > for the build process. If I increase free memory in this area either > by reducing the rootfs size of by adding a few more memory segments to > this area, the build goes through fine. I'm still curious to see what "sysctl vm.phys_segs" says. It sounds like roughly half of the direct map region is going to DRAM and half to memory-mapped I/O devices. Is that correct? > I also found that when the build slows down, most of the pages taken > from freelist 1 are allocated by the UMA subsystem, which seems to > keep quite a few pages allocated. At worst, it may be necessary to disable the use of uma_small_alloc() for this machine configuration. At best, uma_small_alloc() could be revised opportunistically use pages in the direct map region, but have the ability to fall back to pages that have to be mapped. Alan