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 19195566A; Thu, 14 Nov 2024 14:43:22 +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=1731595403; cv=none; b=Jmy7fCTWHMcbW87ep5OrN9MfqXuoJXvKXMB8fJoRZKQvtPrsPDvn9mgs5SmvjT1a1K0+JNCI2C9qnp5UJHnB86cyP+fi3aSiMHOUSVVgsL3eOSRuOutMyNCAfEm6AwGvlIizjfVpamz+AWUOWACNhx96a6k35SBJo/OHhmJkpuQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731595403; c=relaxed/simple; bh=b6kWf9cYtlJIUgG9DFXxGeUKCKiMGwyX3lpYWJ0d3dw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QcY5FMciG1sEqTgok6xxM6/ArCd9p4i/QIXybvXpP8z65PJau8PEkIBJXx61JMzOWE7sy4JnGETzl/JenqYwb+PrCBwf6dpPl8L3G6A5xih2UkpEO5L2PJVTBOlL1rc8jin+4h0OjR4fvkImwr2H9NmlDrCOXZIeBZLR8b37Z6I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lrysDd0U; 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="lrysDd0U" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8FD97C4CECD; Thu, 14 Nov 2024 14:43:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1731595402; bh=b6kWf9cYtlJIUgG9DFXxGeUKCKiMGwyX3lpYWJ0d3dw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=lrysDd0Utmp638DNgzcrS2JTtGIUmvFc9tIbO26XYFS+P+lzG2pzjXrO9LVRi6H0V etprv2mezDAURqsh2ytixH/2vjBVaGYeEgl4kb+J1ta25tozwAhfYpSootgKlvr565 H3zW6CsZ2/6oj0f7H++asIk0CDDwgMybtkGppStu2GNzlkWF/6QIyIjHuYuZ/P1iF4 JumGSevHEEoI/U4ZTK4/vnjG/cCNv6qS3F76IpB2yftuhly0jIni1d31aBBTKDcGdw YCIapasA0wGJCxeVRZCtV40jN1vP0uxIdhQS45CThCCeUuf+F6DYzyJHUAPPBIjp71 +vPJnv0ud9G6Q== Date: Thu, 14 Nov 2024 08:43:21 -0600 From: Clark Williams To: Sebastian Andrzej Siewior Cc: Huacai Chen , Huacai Chen , Xuerui Wang , loongarch@lists.linux.dev, Steven Rostedt , linux-rt-devel@lists.linux.dev, Guo Ren , Jiaxun Yang , linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/3] LoongArch: Allow to enable PREEMPT_RT Message-ID: References: <20241108091545.4182229-1-chenhuacai@loongson.cn> <20241108091545.4182229-4-chenhuacai@loongson.cn> <20241114103111.5W5ZY0D4@linutronix.de> <20241114111409.LWKp5YEg@linutronix.de> <20241114113018.Ilo9ZsQo@linutronix.de> <20241114132956.wafcHvaB@linutronix.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241114132956.wafcHvaB@linutronix.de> On Thu, Nov 14, 2024 at 02:29:56PM +0100, Sebastian Andrzej Siewior wrote: > > Ach okay. So the pure read on the slow bus causes a delay because the > CPU is stalled. That is not limited to chrony but should also have an > affect if the user uses hwclock to read/ write the time. > > Sebastian > We see similar problems with chronyd accessing the RTC on aarch64 systems that use UEFI. Accessing anything via the EFI Runtime is very slow. Probably going to turn off 'rtcsync' in chronyd when running low-latency workloads. Clark -- The United States Coast Guard Ruining Natural Selection since 1790