From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.128.51 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793452187; b=XOzepMc4yjJMfx7UF3X9OeLJZGfe1wup4cYgT2hHETkfPwPXP9iLYVuH/asnWa3VQrb9 va96aBQuLimwVFh0IBwh4jkx0aDKtiYCyseMeYx3U49UfBT7mZGmKEIY843DRk+j0JTmW WX/3TDpz0LNl5pb1SzOpzGRIlUvEqAr4YONf7pAXmyMgNOmyvRzTwkxdZ5G6KJJRhNmbr YLFUzNPqiQdF3Z/2L6jhF+G4cnUgoP1pv8ad4d1l5e3Sse0KeDDI7h5T1lnc90Z9Sc3C+ tI3rRSI51fQt7ZAtwb3Y22tVWgxMJb5vBQAUnHTqGlkZX65gYa/QYnqL+ZEpweFm6gA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793452187; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; bh=AsdiVPeKCV3aUvIOkRhblwdU+P9wwsjvQNPDztlCLtg=; b=aTlB317JXkyRZLkb+HUxRgL+WjXhmXv55+saN9KPdJReN4lNxl2RuZf8Rt3fNdozjW4i ufQ+hFUrPs69vQcWmC577aeM7Ybfr1pv0ZhhBViA9FJcnVSPVvgaxRU7KoYSo0+TGhgFm Bx69jqpl1jsxYScjKUa1z9XjMpx+nqCF+Y6ZK1kOodHbTb+rgr0ELa0X4S4HcXo7vANAp sLsplFld/E25RxoFjRXJf6omLtuTZ9BywVdGGmXxJoynLUTc7erN3GweYoZaHUDmw/He1 +F0ih/af8qLfARpihSFvbQeiH35r8FTaCgJ7FGnSjp50LjxOU/zD8JJXbQFR7Dpm+pQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=RxeMOBRz; arc=none smtp.remote-ip=209.85.128.51 Received: from mail-wm1-f51.google.com (mail-wm1-f51.google.com [209.85.128.51]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 467A3606A31C for ; Sat, 31 Oct 2026 13:09:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 467A3606A31C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=RxeMOBRz Received: by mail-wm1-f51.google.com with SMTP id 5b1f17b1804b1-4a5720b0a57so14575345e9.0 for ; Sat, 31 Oct 2026 06:09:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1793452186; x=1794056986; darn=vger.kernel.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=AsdiVPeKCV3aUvIOkRhblwdU+P9wwsjvQNPDztlCLtg=; b=RxeMOBRzQmRKcwf4nK6sXXNdsBGVz1qz1nDToSx14ab685t5VjxsmPcMXeOEQyhY07 fIIPBczc2NnPf1QzoZMXnEe52BiwR8yRD79bznx1uW6fubjvEL4T1UiJGNrw47JojUHn BYZK5Q4/QgtKXW/Iot+7yGCFWe8JaDMmIAYFRgm8sUyUEqBBZ5vQXWS+ixnS0RceIWlU BwoKXWWGeV/UpwXxnW2wi6FDfHbGHE/V0Vk8j5ukqpovlkT+gww676t3AFyoe02lrGv3 dGiX6naGF+5ooLCGy7bcOKVNEtOA7JPNpFT/qxZC+NTgA5UGPRcb3O61XfoheeW3ALmu 1CkQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793452186; x=1794056986; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=AsdiVPeKCV3aUvIOkRhblwdU+P9wwsjvQNPDztlCLtg=; b=rba1c3p4a9ASvgce2AvXu7CMy3GbR9kCbe4BYpWYe/lLlnL+vXYgrfYLVtxSiCU4gk aL+bGLWAayqmNIQmv6Gq/wzdkCV+oLavPrvbYKjA6hDgp74VhCKUtn4AGBmVQovexWeQ Tm/hvZJxxbqghHFHO9vfs+P+EkckZcUmx+QX4FXEpiMPi2iYwa1cCqCAgypzzx9lflQh ME64zUPbFSv1vrqY3F6oQd3hWCyHOC1O1UAksTfl4CzcJrz+Td5s6+nCIBhEglesDDQN Mz1RmTxxOk2NJYJK/4C/SqtF94/2EJQoJAr6K/EXPX7FIPjEWtJ4jXZNw3b24p4poLNQ 4uIw== X-Forwarded-Encrypted: i=1; AKwUvBxYMqHTaZNgsvYOLGrZ0p6E+dRNyRcTR+LuBE3b7EnWj296oH/HRqbeA0/ucBLOFGSfjY0vKr049BSV70g=@vger.kernel.org X-Gm-Message-State: AFq9FYLQjCfGGa8q3IAHJEm5jJtgcD78DojsMix52R6XXf868DZy+Wcg ITQiGGQIYto3FY6/61SocGwgIJ9+IGWuVTyFYxt15gS223JfRt1cJCpW X-Gm-Gg: AYBFou23k0j3PzG1Z182cqWGhMMK97iqS5TTEnMl6BF5owoBg2Ew5VbCsJRDtsqt3k1 tSEhoJ9Euchd5Dl+ZT5CVlJMBYowhyVbtJnfvJIZU8Gn1AibQEM/Zr2n2xvtEzixa/xllDr2z2U ktZPiikD2x52W0En9W8OXCsj4q6ceyzoEiRAeoPjjkoI3KUAduthlF8kxSoG5twBc3ospi4kj24 ailsL6D8lSQIqTayeAQyRx3GavqWlf4phBOv92huuCDPhNjnlTZofgWtRAeFz1Trwpuhc+L2gWV 8xvYVRCAYLTIIRdSBHcPGH8VrBzhVczovNE2QXUsK5FI9L71NLy0UYvf9BnTjeUbHBKNpzAzbbz H4yOKw52/IPDXMZZyzfExD4EEJfWB0kOLl1Vng+wLF/bN6QJhOeG5NqgM+Lx14mlKvnSKR1JhR+ vfgYGQzpBNuA65PayLJ4enN5m5M48TlA3njAiW9Z3G2odirnaCDM0yhkKlkUkcQDG/gQua6lD5K WnLfypRwZb5O7kWU4Adwrlz8d65lgMjw/dWY0ogj0kVXZ5SwO3t9Yz7eE3+lHY8mDOOgDoD8NSZ UhKPxptWGf7j+EJRNbXcvTd+YJE2PhaaNxZU/r4W5jIZp/B+u7w1B/pL8i2D25QmTM+soTkcMGM HFymKW/ac8nlZhxWmNtiEC0ha7y/OzMvRMOLrlgto4mxlr9NH+Rx2pJkmB4XIxPo6uw4cIyemEZ TldVDLcBEL2uSPFYHPDA57kWzwikEceIeLMbWrlNSjzzxA/aWZLw== X-Received: by 2002:a05:600c:8b01:b0:49f:c5aa:9ef4 with SMTP id 5b1f17b1804b1-4ac16fa4f73mr122793835e9.8.1793452185480; Sat, 31 Oct 2026 06:09:45 -0700 (PDT) Received: from unknown748F3CBA5068 (dynamic-2a02-3100-a81d-e001-9c9b-db33-f166-0fda.310.pool.telefonica.de. [2a02:3100:a81d:e001:9c9b:db33:f166:fda]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4aa7f322c46sm196891285e9.2.2026.10.31.06.09.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 31 Oct 2026 06:09:44 -0700 (PDT) Date: Sat, 31 Oct 2026 14:09:42 +0100 From: Karl Mehltretter To: Andrew Morton Cc: Andrey Konovalov , Alexander Potapenko , Dmitry Vyukov , Marco Elver , Bradley Morgan , Anna-Maria Behnsen , Frederic Weisbecker , Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Sebastian Andrzej Siewior , Clark Williams , linux-rt-devel@lists.linux.dev, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 4/6] sched/core: Pause KCOV in __schedule() Message-ID: References: <20261005185803.39170-1-kmehltretter@gmail.com> <20261005185803.39170-5-kmehltretter@gmail.com> <20261030142354.bbc5e7f26fbfb6a8eee21290@linux-foundation.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261030142354.bbc5e7f26fbfb6a8eee21290@linux-foundation.org> On Fri, Oct 30, 2026 at 02:23:54PM +0100, Andrew Morton wrote: > __attribute__((no_instrument_function)) > __attribute__((__always_inline__)) > class_kcov_pause_t class_kcov_pause_constructor(void) > { > class_kcov_pause_t _t = { .lock = (void*)1 }, > *_T __attribute__((__unused__)) = &_t; > _T->paused = __kcov_pause(); > return _t; > } > > Adding all this goop to core scheduler functions on non-KCOV kernels > won't be terribly popular! > > A bit of macro magic can trivially make all this go away for non-KCOV > kernels. The overhead is probably acceptable with CONFIG_KCOV=y > kernels - seems it's only enabled for debug/research/fuzzing kernels. > > Ditto the hrtimer change. Aim to make these patches produce no change > in generated code with CONFIG_KCOV=n. > Good point. Leaving the guard outside #ifdef CONFIG_KCOV was an oversight in v2. I will fix this and the hrtimer wrapper in v5. Thanks, Karl