From nobody Fri Dec 20 19:54:10 2024 X-Original-To: freebsd-arm@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4YFJ5D2kg5z5YxH0 for ; Fri, 20 Dec 2024 19:53:52 +0000 (UTC) (envelope-from fbsd@www.zefox.net) Received: from www.zefox.net (www.zefox.net [50.1.20.27]) (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 (2048 bits) client-digest SHA256) (Client CN "generic", Issuer "generic" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4YFJ5C6tJfz4QCt for ; Fri, 20 Dec 2024 19:53:51 +0000 (UTC) (envelope-from fbsd@www.zefox.net) Authentication-Results: mx1.freebsd.org; none Received: from www.zefox.net (localhost [127.0.0.1]) by www.zefox.net (8.18.1/8.18.1) with ESMTPS id 4BKJsAEC093368 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Fri, 20 Dec 2024 11:54:11 -0800 (PST) (envelope-from fbsd@www.zefox.net) Received: (from fbsd@localhost) by www.zefox.net (8.18.1/8.18.1/Submit) id 4BKJsAEY093367; Fri, 20 Dec 2024 11:54:10 -0800 (PST) (envelope-from fbsd) Date: Fri, 20 Dec 2024 11:54:10 -0800 From: bob prohaska To: Mark Millard Cc: freebsd-arm@freebsd.org Subject: Re: armv7, silent hang, low swap, high priorities Message-ID: References: <633E900F-9C67-4956-A628-3A1549A40AF8@yahoo.com> List-Id: Porting FreeBSD to ARM processors List-Archive: https://lists.freebsd.org/archives/freebsd-arm List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-arm@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <633E900F-9C67-4956-A628-3A1549A40AF8@yahoo.com> X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:7065, ipnet:50.1.16.0/20, country:US] X-Rspamd-Queue-Id: 4YFJ5C6tJfz4QCt X-Spamd-Bar: ---- On Fri, Dec 20, 2024 at 09:24:10AM -0800, Mark Millard wrote: > On Dec 20, 2024, at 09:10, bob prohaska wrote: > > > An old (v 1.1) Pi2 running armv7 -current often hangs during buildworld. > > > > It doesn't respond to enter-tilda-control-B and has to be powercycled. > > Once rebooted, buildworld can be restarted and makes further progress, > > sometimes to completion. Swap was configured in two partitions, one > > on microSD and one on mechanical hard disk, thus both over-provisioned > > and wildly unequal in speed. Root is on the mechanical disk. > > > > An orphan top window surprised me by reporting very high priorities > > in the 130 range but swap usage was relatively low, less than 100MB. > > That seemed an odd combination. Usually priorities that high are > > associated with severe memory pressure. Could the mismatched swap > > speeds have confused the scheduler? There were no console warnings. > > > > The machine was fully loaded with a -j4 buildworld, so the fact of > > the hang isn't hugely surprising. The top display, at > > http://www.zefox.net/~fbsd/rpi2/crashes/20241219/top_display > > seemed internally inconsitent. Does it surprise anybody else? > > > > I've since removed the microSD swap, leaving only the mechanical disk > > swap, to see if that changes the hang behavior. > > > QUOTE > . . . > The nice utility runs utility at an altered scheduling priority, by in- > crementing its "nice" value by the specified increment, or a default > value of 10. The lower the nice value of a process, the higher its > scheduling priority. > END QUOTE > > Renice, setpriority(), etc. agree. > > Those 120+ figures are LOWER priority than the under 100 figures, > not higher. It never occurred to me that "PRI" might be in units of niceness. Thank you! bob prohaska