From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-1445413-1522347112-2-11781785070704019586 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.249, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='US-ASCII' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: linux-api-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=fm2; t= 1522347111; b=vDymQcPT2hSVLALmr2SWK+GhrQa9tXliJ+7epseInjyq8BOjH5 HpjbEquDHqCmJOAgm/orSu32L+hoBM8jruVyuyqHftScYs6zyrkmq0k5rDUOyOwc GVM81G6M1JbxB4d7j4FWvR9vDjys0qkNGVOUKQwqb5EBWdO7HZaz8W/irBsGIKVc ZG/FnwgoaRhPiVmdung7WGPkztmrtKi/uKLBQFPpFAnqbQiC9MFebvU+AmPh9DA7 3NJK5FnxmU7iUTNrNMhZCvK76ZTshIsYuTq7jUyKAFRvSuH9fGYOEGObXKiOcc8D XlK1JtzxbxoO0STSalJnZLMUmr06EW7Z6aKw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=date:from:to:cc:subject:message-id :in-reply-to:references:mime-version:content-type :content-transfer-encoding:sender:list-id; s=fm2; t=1522347111; bh=yGa5TwbPusMju0ym5Cis8toPqGJSSDMhLacqWJtdQjo=; b=vix7M4xielZo 0eyUAXy1cN37JMZSb7TvB9YhT7HbrtjLxCg/8WO042PkgU/LAwUzo7TI3byG2826 JdQ2sHvgYHBPqW5xukk9JdiELi2I4usP6fvZZUuvf/maj1amJ60AQWtuGLoa8t0w pPqfgjRw6Fxz6TjHrX3RWPMuOQuo4SYAYWstyMbO1zgEKxSkW5nltdAA0BXOSXZO coSajTIcXEN70NOR+/VDJvgeMBOkNaFhcq4rBKlfYmy1T1tV1oiPdbB1LKcvDyqr XHRd7jxsfeWwXkuFZwuNSqm1yKxmuu8oSTi7NlTTguZ45OdL4S0KHBW55KecsIQp nHIb8Tkz2w== ARC-Authentication-Results: i=1; mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=goodmis.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-cm=none score=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=goodmis.org header.result=pass header_is_org_domain=yes; x-vs=clean score=-100 state=0 Authentication-Results: mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=goodmis.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-cm=none score=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=goodmis.org header.result=pass header_is_org_domain=yes; x-vs=clean score=-100 state=0 X-ME-VSCategory: clean X-CM-Envelope: MS4wfH9SpQKmV3WskjrfNabfRd4srZm4RKMpEkcu+dnxmHX4qF6+jwfQTe/acGEqdqMI0gF5lmdhswqQUepUZg0DnnMC0TNC/JXZ2LCiLCzZ1GJn8Hxs+J5N X/7A34rTKAzAkYxmC8h6WetU5yzA+88DZsujnYs79qhADAzXYzrJW0cD8oV8LMrDR/7pZnugjQFzuxhhx6N9oDVIqjrH+hTi2tIBWuPTfs55TH7j1yJVHYHs X-CM-Analysis: v=2.3 cv=WaUilXpX c=1 sm=1 tr=0 a=UK1r566ZdBxH71SXbqIOeA==:117 a=UK1r566ZdBxH71SXbqIOeA==:17 a=kj9zAlcOel0A:10 a=v2DPQv5-lfwA:10 a=7d_E57ReAAAA:8 a=VwQbUJbxAAAA:8 a=svTxBbp9I1HFmBz0-fIA:9 a=CjuIK1q_8ugA:10 a=x8gzFH9gYPwA:10 a=jhqOcbufqs7Y1TYCrUUU:22 a=AjGcO6oz07-iQ99wixmX:22 X-ME-CMScore: 0 X-ME-CMCategory: none Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754175AbeC2SH7 (ORCPT ); Thu, 29 Mar 2018 14:07:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:40836 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754158AbeC2SH4 (ORCPT ); Thu, 29 Mar 2018 14:07:56 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BDAFE21777 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=rostedt@goodmis.org Date: Thu, 29 Mar 2018 14:07:52 -0400 From: Steven Rostedt To: Mathieu Desnoyers Cc: Peter Zijlstra , Thomas Gleixner , "Paul E. McKenney" , Boqun Feng , Andy Lutomirski , Dave Watson , linux-kernel , linux-api , Paul Turner , Andrew Morton , Russell King , Ingo Molnar , "H. Peter Anvin" , Andrew Hunter , Andi Kleen , Chris Lameter , Ben Maurer , Josh Triplett , Linus Torvalds , Catalin Marinas , Will Deacon , Michael Kerrisk , Alexander Viro Subject: Re: [RFC PATCH for 4.17 02/21] rseq: Introduce restartable sequences system call (v12) Message-ID: <20180329140752.12661138@gandalf.local.home> In-Reply-To: <21903915.856.1522346553810.JavaMail.zimbra@efficios.com> References: <20180327160542.28457-1-mathieu.desnoyers@efficios.com> <20180328174935.GK4082@hirez.programming.kicks-ass.net> <181076499.279.1522268382303.JavaMail.zimbra@efficios.com> <87410797.545.1522331641598.JavaMail.zimbra@efficios.com> <20180329142338.GD4043@hirez.programming.kicks-ass.net> <544124089.623.1522337940950.JavaMail.zimbra@efficios.com> <20180329122439.4a909c72@gandalf.local.home> <21903915.856.1522346553810.JavaMail.zimbra@efficios.com> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-api-owner@vger.kernel.org X-Mailing-List: linux-api@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Thu, 29 Mar 2018 14:02:33 -0400 (EDT) Mathieu Desnoyers wrote: > Currently, anyone using ptrace on a process has pretty much given up all > hopes of performance. Processes will use rseq to gain performance, not the > opposite, so this deterioration will be unwelcome. The ptrace path has nothing to do with ptrace anymore, and probably be hard to notice the performance hit. You simply set a TIF flag, and on exit of the syscall it jumps to a path that checks special cases (tracing system calls being one of them). It's called the ptrace path because ptrace was the first one to use it (I'm guessing, I haven't actually looked at the history). This is used to add any system call checks that are not done during normal operation. And this certainly falls under that category. -- Steve