From nobody Fri Nov 7 17:19:02 2025 X-Original-To: freebsd-current@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 4d35Q10pcqz6GF5W; Fri, 07 Nov 2025 17:19:05 +0000 (UTC) (envelope-from ronald-lists@klop.ws) Received: from smtp-relay-int-backup.realworks.nl (smtp-relay-int-backup.realworks.nl [87.255.56.188]) (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 did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4d35Q05gMnz3ty8; Fri, 07 Nov 2025 17:19:04 +0000 (UTC) (envelope-from ronald-lists@klop.ws) Authentication-Results: mx1.freebsd.org; none Received: from smtp-relay-int-backup.realworks.nl (crmpreview3.colo2.realworks.nl [10.2.52.33]) by mailrelayint2.colo2.realworks.nl (Postfix) with ESMTP id 4d35Py4w9Bz1RZ; Fri, 7 Nov 2025 18:19:02 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=klop.ws; s=rw2; t=1762535942; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to; bh=rh5IP52UgddQaaGh88sb7gYqQ3a6f5UVLKuacNPW76Y=; b=b2Uan4vRK71hGxV/1PoS7K13h41Jh8+Nv+q6jPW71VsAOqVZDBWOIHA/+68aDou5YJBvGf bfI7vCWnD+vSiGowvg356GeRL48ybKXmy0h3bTx1y9FwTAPtelOsKH8qNAj4qn3iWry9+7 xonZFTkW9FlWvD+aId8EvrTv2dJsWvC4+mbylRTEYDdFE7teHMY/1W6yZnSP/Cek6nM8/L Vc2QCw+1UwUURU7KoKr32B2IZ9M8SZtFeL0dOSDH6uo4POvNY7AhcdFi91ViGOWcB2I2cw PF0C4f8E5kks18xj1QVBY+RRxaZ0SRvr93QuM44r4HG8TLSpJifH8Gu3OzkP4Q== Received: from crmpreview3.colo2.realworks.nl (localhost [127.0.0.1]) by crmpreview3.colo2.realworks.nl (Postfix) with ESMTP id 49CF41400A1; Fri, 7 Nov 2025 18:19:02 +0100 (CET) Date: Fri, 7 Nov 2025 18:19:02 +0100 (CET) From: Ronald Klop To: bob prohaska Cc: freebsd-arm@freebsd.org, Paul Mather , freebsd-current@freebsd.org Message-ID: <1019311516.10662.1762535942098@localhost> In-Reply-To: Subject: Re: Arm v7 RPi2 -current unresponsive to debugger escape during buildworld List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@FreeBSD.org MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_10661_1959876907.1762535942094" X-Mailer: Realworks (772.17) X-Originating-Host: from (localhost [127.0.0.1]) by crmpreview3.colo2.realworks.nl [10.2.52.33] with HTTP; Fri, 07 Nov 2025 18:19:02 +0100 Importance: Normal X-Priority: 3 (Normal) X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:38930, ipnet:87.255.32.0/19, country:NL] X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Queue-Id: 4d35Q05gMnz3ty8 ------=_Part_10661_1959876907.1762535942094 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Van: bob prohaska Datum: 7 november 2025 17:48 Aan: Paul Mather CC: freebsd-current@freebsd.org, freebsd-arm@freebsd.org Onderwerp: Re: Arm v7 RPi2 -current unresponsive to debugger escape during buildworld > > > On Fri, Nov 07, 2025 at 10:42:24AM -0500, Paul Mather wrote: > > On Nov 6, 2025, at 9:22pm, bob prohaska www.zefox.net> wrote: > > > > > On Thu, Nov 06, 2025 at 10:00:19AM -0800, Mark Millard wrote: > > >> On Nov 6, 2025, at 08:38, bob prohaska www.zefox.net> wrote: > > >> > > >>> On Thu, Nov 06, 2025 at 03:45:01PM +0100, Ronald Klop wrote: > > >>>> Hi, > > >>>> > > >>>> To me it sounds like your machine is overwhelmed by swapping. > > >>>> > > >>>> Try -j1 buildworld. > > > Maybe a -j1 buildworld could be at least somewhat informative. > > > Lately none of my Pi2's has made it through buildworld > > > without hanging silently. If -j1 buildworld completes, > > > that would be a significant change. The test will take a > > > week, but the problem has been going on for a year. > > > > > > This isn't related directly to building on the RPi2, but just a general comment that on a system with 1 GB RAM like the RPi2, building with -j3 (or anything more than -j1) is probably wishful thinking at this point given it seems the RAM requirements of LLVM right now seem to be creeping ever upwards. > > In the past FreeBSD was quite vocal about running out of memory/swap. It would issue warnings > on the console that swap was low, slow to become available, or exhausted. In this case nothing > of the sort is happening. The machine does bog down when swap usage exceeds about 500MB, but > it doesn't stop or complain. The scheduler seems to figure out which theads are making progress > and gives them higher priority. Eventually the backlog is worked through, swap use drops to > 50 MB or less and CPU usage rises to 90+% per core. > > That's when the system is hanging and unresponsive to enter-tilda-control-B. If it's a > memory exhaustion issue it's happening invisibly and only later causing a stoppage. > It's the invisibility of the problem which hints at a deeper flaw. I don't think it's > possible to anticipate how much memory a program will eventually require, but it does > seem possible to recognize when a resource limit is crossed, if that's the problem. > > I think a -j1 buildworld is likely worth a try, but if it succeeds I don't have > any idea where it'll point a finger. > > Thanks for writing! > > bob prohaska > > > > > > > If it fails without swapping you know you need to look somewhere else. Regards, Ronald ------=_Part_10661_1959876907.1762535942094 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit

Van: bob prohaska <fbsd@www.zefox.net>
Datum: 7 november 2025 17:48
Aan: Paul Mather <paul@gromit.dlib.vt.edu>
CC: freebsd-current@freebsd.org, freebsd-arm@freebsd.org
Onderwerp: Re: Arm v7 RPi2 -current unresponsive to debugger escape during buildworld

On Fri, Nov 07, 2025 at 10:42:24AM -0500, Paul Mather wrote:
> On Nov 6, 2025, at 9:22pm, bob prohaska www.zefox.net> wrote:
>
> > On Thu, Nov 06, 2025 at 10:00:19AM -0800, Mark Millard wrote:
> >> On Nov 6, 2025, at 08:38, bob prohaska www.zefox.net> wrote:
> >>
> >>> On Thu, Nov 06, 2025 at 03:45:01PM +0100, Ronald Klop wrote:
> >>>> Hi,
> >>>>
> >>>> To me it sounds like your machine is overwhelmed by swapping.
> >>>>
> >>>> Try -j1 buildworld.
> > Maybe a -j1 buildworld could be at least somewhat informative.
> > Lately none of my Pi2's has made it through buildworld
> > without hanging silently. If -j1 buildworld completes,
> > that would be a significant change. The test will take a
> > week, but the problem has been going on for a year.
>
>
> This isn't related directly to building on the RPi2, but just a general comment that on a system with 1 GB RAM like the RPi2, building with -j3 (or anything more than -j1) is probably wishful thinking at this point given it seems the RAM requirements of LLVM right now seem to be creeping ever upwards.

In the past FreeBSD was quite vocal about running out of memory/swap. It would issue warnings
on the console that swap was low, slow to become available, or exhausted. In this case nothing
of the sort is happening. The machine does bog down when swap usage exceeds about 500MB, but
it doesn't stop or complain. The scheduler seems to figure out which theads are making progress
and gives them higher priority. Eventually the backlog is worked through, swap use drops to
50 MB or less and CPU usage rises to 90+% per core.

That's when the system is hanging and unresponsive to enter-tilda-control-B. If it's a
memory exhaustion issue it's happening invisibly and only later causing a stoppage.
It's the invisibility of the problem which hints at a deeper flaw. I don't think it's
possible to anticipate how much memory a program will eventually require, but it does
seem possible to recognize when a resource limit is crossed, if that's the problem.

I think a -j1 buildworld is likely worth a try, but if it succeeds I don't have
any idea where it'll point a finger.

Thanks for writing!

bob prohaska
 




If it fails without swapping you know you need to look somewhere else. 

Regards,
Ronald

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