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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0E4ACC433E0 for ; Mon, 10 Aug 2020 21:11:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D6CDC20716 for ; Mon, 10 Aug 2020 21:11:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="vdD96yTT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726773AbgHJVLI (ORCPT ); Mon, 10 Aug 2020 17:11:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60556 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726624AbgHJVLH (ORCPT ); Mon, 10 Aug 2020 17:11:07 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E6E5C061756; Mon, 10 Aug 2020 14:11:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=pSCP9TWK9zwqSv6XuJVuV4uuC8sBqC777asNLKOSMWk=; b=vdD96yTTpkkmNQKWST0BtkFYDy /VWcqt5y2MRXq0O+8T/brnMJMlktZwgwTYPZ6XEWLYFHdlv+P2iZuHPK5oJHlpqeTfv/+KtslhZK7 Z9+UkiGLdD504V/HUWehrU1Fn1V/FU9s3ZIJNV19hYTUxVLrubzpoED469Y8IzyD5JwHetW78z0P4 xUsoeHFGTH41HHMkWOmutf+knrMHDmoJu44+z9ouP0ZBeMOSPVsopHJVWX76/vY/Z77nJXbL10fOk OKQnttJfQDze8P49UBea1dZHAUqkWkH5KEhlHwlN5ThzDCCFxGeWvubvStgy7Os/rNJSdv2Q4Sex9 2ijD4RbA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1k5F4P-0003Na-Px; Mon, 10 Aug 2020 21:11:02 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id F20BA980D39; Mon, 10 Aug 2020 23:10:57 +0200 (CEST) Date: Mon, 10 Aug 2020 23:10:57 +0200 From: Peter Zijlstra To: Jens Axboe Cc: Jann Horn , io-uring , stable , Josef , Oleg Nesterov Subject: Re: [PATCH 2/2] io_uring: use TWA_SIGNAL for task_work if the task isn't running Message-ID: <20200810211057.GG3982@worktop.programming.kicks-ass.net> References: <20200808183439.342243-1-axboe@kernel.dk> <20200808183439.342243-3-axboe@kernel.dk> <20200810114256.GS2674@hirez.programming.kicks-ass.net> <07df8ab4-16a8-8537-b4fe-5438bd8110cf@kernel.dk> <20200810201213.GB3982@worktop.programming.kicks-ass.net> <4a8fa719-330f-d380-522f-15d79c74ca9a@kernel.dk> <03c0e282-5317-ea45-8760-2c3f56eec0c0@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <03c0e282-5317-ea45-8760-2c3f56eec0c0@kernel.dk> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Mon, Aug 10, 2020 at 03:06:49PM -0600, Jens Axboe wrote: > should work as far as I can tell, but I don't even know if there's a > reliable way to do task_in_kernel(). Only on NOHZ_FULL, and tracking that is one of the things that makes it so horribly expensive.