From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from krieglstein.org (krieglstein.org [178.254.28.87]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9FBF52F29 for ; Tue, 28 Jan 2025 12:38:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.254.28.87 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738067922; cv=none; b=mXBJ+Yt0TDa2TIezNqG2hmFsVAtrR7+BeSfCd51/GAp4+IOe17Yb5Pe3KbIjURmS93BK9UkUaBsC3ZQPtO9h+pl3c+TDQafwq+abYezLGB1yxreEySQ8nvcrTUGedQXmeYtPBUBiikpgj9qQYDsTUvTwIcH2RbI8erBmfIqwH0U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738067922; c=relaxed/simple; bh=scPL2EVrE3+kNWt5w0xhALz5frCNCyacUc75MjiiHjs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=czNTD3oDbjofh3Jen8SLG3qqfIMKlW0ksO2x8OIM6FLTAAi/56wXUZc0Ka2AAvR/VnkoxSgA6hEfDGQ6vahaGTr469ytr/ITKX0HDsmZfFBFPraOKcKctoTRgcPA027QIZo/DJIY1S8OWU7l0KjSUodzM4YHn2nP0+HFbr3ys+U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=krieglstein.org; spf=pass smtp.mailfrom=krieglstein.org; dkim=pass (1024-bit key) header.d=krieglstein.org header.i=@krieglstein.org header.b=hhaiUO6m; arc=none smtp.client-ip=178.254.28.87 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=krieglstein.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=krieglstein.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=krieglstein.org header.i=@krieglstein.org header.b="hhaiUO6m" From: Tim Sander DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=krieglstein.org; s=selector1; t=1738067459; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=SZACzEivFOg5h1PCEyS06h7JNf0SOUhpBY4qE91dQSY=; b=hhaiUO6mqy9lPDH+Gg/sFUD9hv49Xlxc26nuGErK5uvU7N2TJrREn+l8V7C3pYxKJ9sp9J SjUG8bAy0ZxM9W4HsaxlYg5F5+dKscK4dTmDaOd1xVo78rRuz/3UvR+vZ1H2H6vIY4swFA +/uJ3wq+eomYboBE9wLGzOD+pJwmjVY= To: Sebastian Andrzej Siewior , Florian Paul Schmidt Cc: linux-rt-users@vger.kernel.org Subject: Re: Raspberry Pi 5 and PREEMPT_RT (6.13.0-rc3) Date: Tue, 28 Jan 2025 13:30:59 +0100 Message-ID: <4625492.LvFx2qVVIh@ripper> Organization: Sander and Lightning In-Reply-To: <6b290601-7112-410b-9a85-bde02f62d7c3@gmx.net> References: <20250107143937.d_ho7CXb@linutronix.de> <6b290601-7112-410b-9a85-bde02f62d7c3@gmx.net> Precedence: bulk X-Mailing-List: linux-rt-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Authentication-Results: ORIGINATING; auth=pass smtp.auth=tstone@krieglstein.org smtp.mailfrom=tim@krieglstein.org Hi Just my 2 ct. Am Mittwoch, 8. Januar 2025, 10:48:56 CET schrieb Florian Paul Schmidt: > Hi! > > On 1/7/2025 3:39 PM, Sebastian Andrzej Siewior wrote: > > On 2024-12-20 14:18:43 [+0100], Florian Paul Schmidt wrote: > [...] > > > The backtrace appears long but everything up to folios_put_refs() > > appears preemtible. Then there is the interrupt handler. This looks > > okay. > > That was my impression as well. Nothing really surprising (at least for > my limited knowledge in these matters.) > > > Based on this trace, I don't see a section which disables preemption/ > > interrupts and be the reason for the interrupt happening. > > > > One thing that could delay your doing are small caches. > > Then there is looking within the system: An inaccurate/ low resolution > > clocksource and/ or timer device. It could also be the TLB infrastructure. I found that these events can also be very time consuming, probably combined with memory contention? I think this might be traced with performance counters but i never looked into this further than musing about the possibility. Best regards Tim