From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 A2ED03947A6; Wed, 4 Mar 2026 09:03:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772614985; cv=none; b=fjMeOUXZ68v+bDwBJzUxajrD+mVSxrPtmto0juNdYH2G9llRN6pdyykN0dTuPvAVdcfQHJzyE1FpcuanJFSNV5ayAq26pEWO/mh1NI37vWokY+NJeJgroU19M9zScLqYC46XhqsuxI+X6+U0yinNmRAjnNyTvGpAoWYi7qXXim4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772614985; c=relaxed/simple; bh=yj+jUZNT7cASBsqhvAOM40VL/I4ioUX/XHkRcdszmSI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=BslWRyhBfjZG4Lzf9eHDFYBaew+dq31ehzLNwgQzONm41jyp5e+3fQMLczZ8wCCrrIWxKgnSr4jK9g0ttOeal2jVTqgYV+G/09cmJcKTSyNAR3b8cRYAa5CAzoaLHGYBS/F7T0QARC7HJJyLK4GFXN9LGM/UrK4UNelk5DjQgfg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=RhrRCtX4; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="RhrRCtX4" 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=yj+jUZNT7cASBsqhvAOM40VL/I4ioUX/XHkRcdszmSI=; b=RhrRCtX4O9mHG3fMN3lkWlGeF3 loSEPHAYuUf1zeRGYeYM0kzuQQ6q5vDCtESnNgeDSEVvcLalMsr0kr44vz/SraDKokPNEfS0Rm+mv ZxWUEBwQ9ZM9cJ1PY9A6xyAvDARsxMaVAEZiYGwRLAT6csYVcVINmkpWoo6RNx7Ak0UggbN7OcyUe AVAhnlL03iIPNHA/4uZ80J8QuM59A/rqsKt08jwe6AFty8zJdymuN4bB+abtOiPjQUCYvUJRRkCvB FBWGUJ0CigwMM9bFytYR4btifnrNzhrBNTrEaD2U+X3FZ1o2rHsLzooRGo9KE/0MVzxeCOiVYFaC4 O3dDqMfw==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vxi87-0000000D0xT-1dF9; Wed, 04 Mar 2026 09:02:55 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 1E358300B40; Wed, 04 Mar 2026 10:02:49 +0100 (CET) Date: Wed, 4 Mar 2026 10:02:49 +0100 From: Peter Zijlstra To: Yafang Shao Cc: mingo@redhat.com, will@kernel.org, boqun@kernel.org, longman@redhat.com, rostedt@goodmis.org, mhiramat@kernel.org, mark.rutland@arm.com, mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [RFC PATCH 1/2] locking: add mutex_lock_nospin() Message-ID: <20260304090249.GN606826@noisy.programming.kicks-ass.net> References: <20260304074650.58165-1-laoar.shao@gmail.com> <20260304074650.58165-2-laoar.shao@gmail.com> Precedence: bulk X-Mailing-List: linux-trace-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: <20260304074650.58165-2-laoar.shao@gmail.com> On Wed, Mar 04, 2026 at 03:46:49PM +0800, Yafang Shao wrote: > Introduce mutex_lock_nospin(), a helper that disables optimistic spinning > on the owner for specific heavy locks. This prevents long spinning times > that can lead to latency spikes for other tasks on the same runqueue. This makes no sense; spinning stops on need_resched().