From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from outpost1.zedat.fu-berlin.de (outpost1.zedat.fu-berlin.de [130.133.4.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 992BD2F7EE6; Fri, 15 May 2026 17:51:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=130.133.4.66 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778867500; cv=none; b=SJh4JrzhbP4Ld0aY0r5vLlK+F1YLT+2uR59JLEL51wpfMTmwUNZfJksYYttTob/PcA+hA98UnlNQ2kjH60khTKIbV9mWHaBlFI00TmgY5xNseA3MxXJITWSknCTo2BBwNpfG/BEWkahGKxks5OWWxOmwGB18wCUS4jyRFHd7j8E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778867500; c=relaxed/simple; bh=gsQASe5VLtTK1CsE8cqevHSBFe/A5STk4AhJ2klQIWM=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=UjEv3loxMWJKWezZt17kx/dgMq4y0REYqlVFxXYa0+tjyNjHrc/zLuP3nAphn+ZYXUBsVh+MNEbZ9bIz7Gqb6C9/I8iAIZMM99zB0CRRlGHEAFXOpFQf7/XJaiFiXsKfcGKNfmXkK7/alvBGNl7t7hJwVtKunRhb82aBVPWoVhU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=physik.fu-berlin.de; spf=pass smtp.mailfrom=zedat.fu-berlin.de; dkim=pass (2048-bit key) header.d=fu-berlin.de header.i=@fu-berlin.de header.b=dwPIg/f7; arc=none smtp.client-ip=130.133.4.66 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=physik.fu-berlin.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zedat.fu-berlin.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=fu-berlin.de header.i=@fu-berlin.de header.b="dwPIg/f7" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=fu-berlin.de; s=fub01; h=MIME-Version:Content-Transfer-Encoding: Content-Type:References:In-Reply-To:Date:Cc:To:From:Subject:Message-ID:From: Reply-To:Subject:Date:Message-ID:To:Cc:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:In-Reply-To: References; bh=HDc8Rbn6gSc83YkMlQR58q1uD3nHw5WFwhRyJ1E+IXA=; t=1778867496; x=1779472296; b=dwPIg/f7kWv2ASd6w8Ond9dTst4U5tVZTXABk4TTpbjKoe5LaAXwx2X40sqr9 R+4kBWLz37Vy3c2YCvGxtepXVgIJ35c4jNgYW7jkLxLwV2vbKlPJlNvS/0nIOsptCfZuDufLXG4ic B8TzFq/eTJz16ZAg5mlwuqilNZm++a2o2ecPlNPqAsSHInUqEOPGUpCdEedqeoJMHuu4i/mpxL4J8 HrRxiUMfcuM+3W2sM0hw1Wbpb2Lcfm+1UMQy5Wu4o9Gl08YEAVw1v11GVrvuPxhrFBVlqdFfoRU0h wT/Xrtp+y1Rephx9d91t+TTmk/unBBjG4m+C1geGVIhnfOYrPw==; Received: from inpost2.zedat.fu-berlin.de ([130.133.4.69]) by outpost.zedat.fu-berlin.de (Exim 4.99) with esmtps (TLS1.3) tls TLS_AES_256_GCM_SHA384 (envelope-from ) id 1wNwh5-00000001x7R-3CyX; Fri, 15 May 2026 19:51:27 +0200 Received: from p5b13a134.dip0.t-ipconnect.de ([91.19.161.52] helo=[192.168.178.61]) by inpost2.zedat.fu-berlin.de (Exim 4.99) with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (envelope-from ) id 1wNwh5-00000001Za4-1mX9; Fri, 15 May 2026 19:51:27 +0200 Message-ID: Subject: Re: the stuttering regression in 7.0: should I have done something different From: John Paul Adrian Glaubitz To: Thomas Gleixner , Tony Rodriguez Cc: Linux kernel regressions list , LKML , sparclinux@vger.kernel.org, Thorsten Leemhuis , Linus Torvalds Date: Fri, 15 May 2026 19:51:26 +0200 In-Reply-To: <871pfcznw0.ffs@tglx> References: <1c165caf-36b4-4673-97fd-ed86bef17b88@leemhuis.info> <3332123b-9e11-4895-9ab3-1707fba5815c@gmail.com> <871pfj9cmj.ffs@tglx> <088e6cfa-0167-4748-af6c-458ade2f303a@gmail.com> <878q9p82je.ffs@tglx> <64f465ca-6117-4375-9c4b-af771b8205fd@gmail.com> <87tssb6olo.ffs@tglx> <87qznez3tf.ffs@tglx> <0669f754-a313-4aa3-9923-0c374d49feb3@gmail.com> <871pfcznw0.ffs@tglx> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Original-Sender: glaubitz@physik.fu-berlin.de X-ZEDAT-Hint: PO Hi Thomas, On Fri, 2026-05-15 at 17:35 +0200, Thomas Gleixner wrote: > > Thank you again for the debugging guidance and for the feedback on my= =20 > > original patch addressing the timer starvation issue. It was a pleasure= =20 > > contributing to the resolution. >=20 > Thank you for going through the hassle of chasing it down and providing > the debug data to analyze it. >=20 > I'm still puzzled how this went unnoticed for almost two decades: >=20 > 112f48716d9f ("[SPARC64]: Add clocksource/clockevents support.") My suspicion is that it was previously visible only in certain edge cases, in particular on machines with many cores and high load. Case in point: In the past, SPARC LDOMs with lots of virtual CPUs could crash in rares cases when building packages such as GCC or LLVM and running their testsuites. I don't know if Tony's patch fixes this long-time issue that we have observ= ed in the past on Debian's buildds, but I think that the chances aren't too ba= d. Tony, please clean up your patch and add an elaborate explanation in the co= mmit message! Hope to see this fix landed as soon as possible! Thanks to both of you for hunting this down! Adrian --=20 .''`. John Paul Adrian Glaubitz : :' : Debian Developer `. `' Physicist `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913