From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BC59CA0ECA for ; Tue, 12 Sep 2023 12:34:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235130AbjILMeJ (ORCPT ); Tue, 12 Sep 2023 08:34:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235141AbjILMeH (ORCPT ); Tue, 12 Sep 2023 08:34:07 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 42F9F9F for ; Tue, 12 Sep 2023 05:34:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=5TCd/VnMsUN2Xfg7sAjE+O/bMQ8NXxyvyk4g9OIV6gs=; b=jN91iTAqHkXMEwG5tjKOoJZgTs h7vfBm5tgEKymnY709XBHN6mXRzvLY/RlK/iuwQAGWcRCencHAXvRSky1n6i1Uv50iT5FLCvg0Fh+ uXjVCE/AfhgtLUGLP3l0T093oMiiknWbssPvbdav0lBxkpRDzjTrfkNAkJUiVQxdScB0qcyFmbKWb FsFaOhd/SNYgy6D8xM4TJ9wLrhfw8ef0uLRzXQzBiO8XuQAsQa/nHzgvYC69c3o5S3c8+M/tFrltU kqD7tmmP9zddhY5e5QeeiMaKEr7AWnFJyzVuSAJ0xAgpMLFM3NRioZznpcsyjEQoE5uZU8eNk5QBn HJFfpCTw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qg2aa-007aMi-Jz; Tue, 12 Sep 2023 12:33:56 +0000 Date: Tue, 12 Sep 2023 13:33:56 +0100 From: Matthew Wilcox To: Peter Zijlstra Cc: Ankur Arora , Linus Torvalds , linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, akpm@linux-foundation.org, luto@kernel.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, mgorman@suse.de, rostedt@goodmis.org, tglx@linutronix.de, jon.grimm@amd.com, bharata@amd.com, raghavendra.kt@amd.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, jgross@suse.com, andrew.cooper3@citrix.com Subject: Re: [PATCH v2 7/9] sched: define TIF_ALLOW_RESCHED Message-ID: References: <20230908070258.GA19320@noisy.programming.kicks-ass.net> <87zg1v3xxh.fsf@oracle.com> <87edj64rj1.fsf@oracle.com> <87zg1u1h5t.fsf@oracle.com> <20230911150410.GC9098@noisy.programming.kicks-ass.net> <87h6o01w1a.fsf@oracle.com> <20230912082606.GB35261@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230912082606.GB35261@noisy.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 12, 2023 at 10:26:06AM +0200, Peter Zijlstra wrote: > > How expensive would be always having PREEMPT_COUNT=y? > > Effectively I think that is true today. At the very least Debian and > SuSE (I can't find a RHEL .config in a hurry but I would think they too) > ship with PREEMPT_DYNAMIC=y. $ grep PREEMPT uek-rpm/ol9/config-x86_64 # CONFIG_PREEMPT_NONE is not set CONFIG_PREEMPT_VOLUNTARY=y # CONFIG_PREEMPT is not set CONFIG_HAVE_PREEMPT_DYNAMIC=y CONFIG_PREEMPT_NOTIFIERS=y CONFIG_DRM_I915_PREEMPT_TIMEOUT=640 # CONFIG_PREEMPTIRQ_DELAY_TEST is not set $ grep PREEMPT uek-rpm/ol9/config-aarch64 # CONFIG_PREEMPT_NONE is not set CONFIG_PREEMPT_VOLUNTARY=y # CONFIG_PREEMPT is not set CONFIG_PREEMPT_NOTIFIERS=y # CONFIG_PREEMPTIRQ_DELAY_TEST is not set