From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 BCB5935E1DD; Fri, 15 May 2026 19:57:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778875051; cv=none; b=Ky9mm6CsFFMISgCawlDfS618VzTPKu/sfzz/s6jtuOJkNuESSUmWgtEjzkm9fJvB5BOuL+dpBoV/o27RxMAzYJXa/K6tzVRKeyyQYdmDXG8eFqREK9Mpfh1cDDGF2MMe7oojSEnULUiu3fdIoD7+pCzpvbVbOJuYyXQF9S5zOOc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778875051; c=relaxed/simple; bh=RcxWdxyOtt3pt04+C5YwWOqopc6gNCYhI8U1a+BYkJU=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=Rxw16YDZ+kUd6z5NY3ttds0HNH7qaR/indi8GOOWKMlT3LJioSV7akvd3uCFtXff00gUNMjoqvGJquROgmv3eyBNqFkNdAWibTFtgbbRKEtQ8wm5Y8JeJP1DBh0Z4hkioInHkhQTLssrBZpLrX5smCGKZp3UPWoHDv/M/9PQjRw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HfG+Xc92; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HfG+Xc92" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C91C1C2BCB0; Fri, 15 May 2026 19:57:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778875051; bh=RcxWdxyOtt3pt04+C5YwWOqopc6gNCYhI8U1a+BYkJU=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=HfG+Xc928ulaLjMPWEV/pB4ilpCrrZeiWLQSrLaHrqkXohnAfxYdXspfqczhtQ6TK lTREExRXGhC5AU8Sq6VVPyrAS4C/kmH1zK2hmeggpkVKPEdQ3BQYOhqoeAf4q5C/xi GxwLsxNz1VJWumYwH1Y+JfqkQfbWp+sVVozDsQN3WOJUGQlYBEf0TmbflP/oLI2noh y8JglzauKVTQP6m0CtPkUpgfSFbquBz8OTmRa6C+5OjSTIepE9+bi8GYWitZ9A34e9 e0XOACnNvO/9YaPpi5EzhyJML8E6Uf55nVroqW9qQ/OHhrxdrcaXwhu2ps+kM2xira yyTzQ9m7RMgPA== From: Thomas Gleixner To: John Paul Adrian Glaubitz , Tony Rodriguez Cc: Linux kernel regressions list , LKML , sparclinux@vger.kernel.org, Thorsten Leemhuis , Linus Torvalds Subject: Re: the stuttering regression in 7.0: should I have done something different In-Reply-To: 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> Date: Fri, 15 May 2026 21:57:27 +0200 Message-ID: <87se7sxx7c.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Hi! On Fri, May 15 2026 at 19:51, John Paul Adrian Glaubitz wrote: > 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 >> > original patch addressing the timer starvation issue. It was a pleasure >> > contributing to the resolution. >> >> Thank you for going through the hassle of chasing it down and providing >> the debug data to analyze it. >> >> I'm still puzzled how this went unnoticed for almost two decades: >> >> 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 assume those occasional failures did not leave conclusive hints around. > I don't know if Tony's patch fixes this long-time issue that we have observed > in the past on Debian's buildds, but I think that the chances aren't too bad. Good luck! > Thanks to both of you for hunting this down! For some stupid reasons I like such puzzles :)