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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id A50AFC433EF for ; Fri, 15 Jun 2018 05:07:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 63097208D7 for ; Fri, 15 Jun 2018 05:07:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 63097208D7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755674AbeFOFHM (ORCPT ); Fri, 15 Jun 2018 01:07:12 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:47318 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755643AbeFOFHG (ORCPT ); Fri, 15 Jun 2018 01:07:06 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A650C818BAFD; Fri, 15 Jun 2018 05:07:05 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-116-61.ams2.redhat.com [10.36.116.61]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 13C3863A4B; Fri, 15 Jun 2018 05:07:01 +0000 (UTC) Subject: Re: Restartable Sequences system call merged into Linux To: Pavel Machek , Mathieu Desnoyers Cc: carlos , Peter Zijlstra , "Paul E. McKenney" , Boqun Feng , Thomas Gleixner , linux-kernel , libc-alpha References: <1084280721.10859.1528746558696.JavaMail.zimbra@efficios.com> <31fc101a-295b-067b-1a82-7e9e509fc92f@redhat.com> <305409897.10888.1528747473727.JavaMail.zimbra@efficios.com> <091061df-3482-8762-30e4-feaf3417be11@redhat.com> <417742741.11550.1528821084084.JavaMail.zimbra@efficios.com> <20180614122759.GB8798@amd> From: Florian Weimer Message-ID: <608bdd59-9ddb-bf68-0127-a0c54002b582@redhat.com> Date: Fri, 15 Jun 2018 07:07:01 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180614122759.GB8798@amd> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Fri, 15 Jun 2018 05:07:05 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Fri, 15 Jun 2018 05:07:05 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'fweimer@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/14/2018 02:27 PM, Pavel Machek wrote: >>> Should we treat it the same way? Always allocate it for each new thread >>> and register it with the kernel? >> >> That would be an efficient way to do it, indeed. There is very little >> performance overhead to have rseq registered for all threads, whether or >> not they intend to run rseq critical sections. > > People with slow / low memory machines would prefer not to see > overhead they don't need... I can try to get rid of the >500 byte per-thread area for the stub resolver. That should compensate for the overhead introduced. Thanks, Florian