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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 85869CA0EC3 for ; Tue, 12 Sep 2023 12:34:07 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 07CB76B00E0; Tue, 12 Sep 2023 08:34:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 02B6B6B00E1; Tue, 12 Sep 2023 08:34:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E5D836B00E2; Tue, 12 Sep 2023 08:34:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id D8F9C6B00E0 for ; Tue, 12 Sep 2023 08:34:06 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id AD33F160235 for ; Tue, 12 Sep 2023 12:34:06 +0000 (UTC) X-FDA: 81227887692.25.5E0FDE4 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf25.hostedemail.com (Postfix) with ESMTP id 024E6A0022 for ; Tue, 12 Sep 2023 12:34:04 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=jN91iTAq; spf=none (imf25.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1694522045; h=from:from:sender: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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=5TCd/VnMsUN2Xfg7sAjE+O/bMQ8NXxyvyk4g9OIV6gs=; b=yykEuMKjixapEAEg0SkCzXHI5YczUH8MnrfmhZtRd9q1o0p9MRdyuMsu2bgt9UOGNUBuk6 KLmu6T1PvqvquRWNXyA9O17xfkfploxoSs8ESwKgpxhVlfiwjX8pipjrivEXxlCCK4cJaX w8V5q4i+itkptZBLwHuT4ebM6NRxzpM= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1694522045; a=rsa-sha256; cv=none; b=wglsomjIPNNH0o3D5mtVGYam4cJXon+azLnwT86qk/zIIj/HNjE3JYPqWN9XY/vCwJNpjn 66PxTLpOYWqEqSgkQKXeXUUIXACEzD+2cGv7f8zCZeyK8JOwtLK+BIyeZ9kr30PYe5+MvN EIEoIpHBz8JuFIYrMMxfOn3NHYGKy+Y= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=jN91iTAq; spf=none (imf25.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none 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> X-Rspamd-Queue-Id: 024E6A0022 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: qo5xx7be6t31a6on6e6oz4jnhsjw4ecf X-HE-Tag: 1694522044-928133 X-HE-Meta: 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 kkeO91f6 tHDgH5eRBLWE9905AyK+LWfw8nmciYRP2oWAeagdimHh7TJd6wx6UKZAG587WzSK53h/yYezQ0NlZL9fzo1YUg4L/8b3nPWP2dDMXr2wWbRE+yCmC4s72AZvEL24OQXy0ueKBZJzG9wSoGY7PnqqH6KHJrJamLjGmewEYbnuHji7n1bPRzx/FaiiD3Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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