From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 AFB18191499 for ; Wed, 29 Jan 2025 19:55:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738180547; cv=none; b=Zj7iTTCubgkYD9AzQQDwxBXKlKc6tUVp/syLVk1tUKH5pqya9cJy7DRHAI+M+macrf21TM3D7PkipUpRos97u2kjgCNG5/G60hTp6hl7eR9qTMqQSDNOFrtGVJxqFA/iP3QefEfMQ/B4HJb6ajjS6hJYncR/qXrOjHqgSdMemnc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738180547; c=relaxed/simple; bh=ydKCCCUGfR8+WTIWPYNbOduqt5jqLRjHt843D1prIdY=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=lwlZ4cUkFn1oIxLb+qfKbe389ga5Pq5O6c30Kta1Rklkm0RituqE+uQU+NQM1T6i9kVRzFQq41PGzOmNOjY3xt/rLZIb0u1V8D9KWSgOnNCHE7RYYPrEULoC8pFyUmI51Z3arWRN7VjnjFx2taxcG3Ry6r/2s4eNW6KIzw9rTJY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=2aEjgdA2; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=QT+dCDzv; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="2aEjgdA2"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="QT+dCDzv" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1738180543; 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:references:references; bh=706M8veWflnkfxft5otKyZK4NQrhItaWbGp/S0j9cNo=; b=2aEjgdA20XQGovHHmWJNdPKZch3womxjtwp7Cbg0wbRWkQcwX4sa+UOHvLVArbtSAZjNmy WJKH6iGfWl4eEnihWF9Ula1NGJ3b2XeHTEyrmifrgOFU7mMkhm0/DyZruCqu5GEkhMhbYW 6Qg2EBKmPkqkuQ4l1uz7lUnZHdKfg9b2MvlBgAQwd0SLel+yCIcMq5dWm1IINPRKTJZmUK 9osoL/Dtq4Cmhb0Gm50tQMsj8i6TkBtmpDj2zshCsUJhNw6YI2wAqJtryOd2f6Iw9hkvmq hlHuENuWJsLBZ59uOHI0wueQxsY+AQEEcrtxwGgFijOUOQu+C+FndHNmOgbPHQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1738180543; 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:references:references; bh=706M8veWflnkfxft5otKyZK4NQrhItaWbGp/S0j9cNo=; b=QT+dCDzvYKkGx0UzW2AuzJpIZoZRMqldbBLSRjXX1zuWLiZf64ihPxlXfFuLntELKJNNjV +OithyJVXMOkqnDA== To: Waiman Long , Sebastian Andrzej Siewior Cc: John Stultz , Stephen Boyd , Feng Tang , "Paul E. McKenney" , Clark Williams , Steven Rostedt , linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev Subject: Re: [PATCH v2 2/2] clocksource: Use get_random_bytes() in clocksource_verify_choose_cpus() In-Reply-To: <5abcb42b-91be-4043-a138-5d97cbcb5378@redhat.com> References: <20250125015442.3740588-1-longman@redhat.com> <20250125015442.3740588-2-longman@redhat.com> <20250129163442.vczSGi63@linutronix.de> <5abcb42b-91be-4043-a138-5d97cbcb5378@redhat.com> Date: Wed, 29 Jan 2025 20:55:42 +0100 Message-ID: <877c6d75tt.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 On Wed, Jan 29 2025 at 12:03, Waiman Long wrote: > On 1/29/25 11:34 AM, Sebastian Andrzej Siewior wrote: >> But all this would avoid having to run with disabled preemption within >> clocksource_verify_choose_cpus() while having the guarantees you need. > > I guess we will have to break clocksource_verify_choose_cpus() into 2 > separate parts, one without preemption disabled and other one with > preemption disabled. I don't think it is a good idea to just use > migrate_disable() as we may get too much latency that can affect the > test result. > > I will send out a v3 patch to fix that. I zap the topmost commit in timers/urgent then.