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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 42254C4167B for ; Wed, 6 Dec 2023 09:15:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232273AbjLFJPn (ORCPT ); Wed, 6 Dec 2023 04:15:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45818 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229459AbjLFJPm (ORCPT ); Wed, 6 Dec 2023 04:15:42 -0500 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7620F10FE; Wed, 6 Dec 2023 01:15:48 -0800 (PST) Received: from pps.filterd (m0360083.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 3B696Bhg029858; Wed, 6 Dec 2023 09:15:48 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=date : from : to : subject : message-id : references : mime-version : content-type : in-reply-to; s=pp1; bh=SWtYvFRREdIALVKLyDoSVDr17RVjA3EfSR1TRvntPyA=; b=lL3rjPyKF+yzmi8hT15gFLdzY4IRDvlLDLfUy08zMc+10toOblwHlL61hxrF4FbLlgNm sKrshiU1ZoD+J/q7JCrmT4SezfU7SmZQi3qxOhk/xkOE8zM5iwRnAQYNFwRwEbRhGJx7 dqLNPur/JQ2X74sFwi5MfwrbPUQ30fDaSbyuluC1Oz7LtbiARDqW0X/NaGfo54F3D+ii 97hWoqU3K72AcY7PaYaaMfZq+6Q5FCxi9Zyj2Rgb/Q8iIV1dcDeKR++NZ6SqAeTqVE9/ VPSss/Amn9SsUKM9FUVwPAi4dzZwK8uyMKceetIIa5oV9Tx93MmSgLQe6m4oqSa1KzzF ZA== Received: from ppma21.wdc07v.mail.ibm.com (5b.69.3da9.ip4.static.sl-reverse.com [169.61.105.91]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3utnw5rf4w-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 06 Dec 2023 09:15:47 +0000 Received: from pps.filterd (ppma21.wdc07v.mail.ibm.com [127.0.0.1]) by ppma21.wdc07v.mail.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 3B68iISK012978; Wed, 6 Dec 2023 09:15:46 GMT Received: from smtprelay02.fra02v.mail.ibm.com ([9.218.2.226]) by ppma21.wdc07v.mail.ibm.com (PPS) with ESMTPS id 3utavjkceu-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 06 Dec 2023 09:15:46 +0000 Received: from smtpav01.fra02v.mail.ibm.com (smtpav01.fra02v.mail.ibm.com [10.20.54.100]) by smtprelay02.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 3B69FhYe27853392 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 6 Dec 2023 09:15:43 GMT Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 414CF20074; Wed, 6 Dec 2023 09:15:43 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 094B520063; Wed, 6 Dec 2023 09:15:43 +0000 (GMT) Received: from osiris (unknown [9.152.212.60]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTPS; Wed, 6 Dec 2023 09:15:42 +0000 (GMT) Date: Wed, 6 Dec 2023 10:15:41 +0100 From: Heiko Carstens To: Alexander Gordeev , Claudio Imbrenda , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, nrb@linux.ibm.com, nsg@linux.ibm.com, svens@linux.ibm.com, gor@linux.ibm.com, gerald.schaefer@linux.ibm.com Subject: Re: [PATCH v1 1/1] s390: mm: convert pgste locking functions to C Message-ID: <20231206091541.6897-A-hca@linux.ibm.com> References: <20231205173252.62305-1-imbrenda@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-GUID: _8WngSJqXJ2xVMxhWcdvX0MIuhbApuBu X-Proofpoint-ORIG-GUID: _8WngSJqXJ2xVMxhWcdvX0MIuhbApuBu X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-12-06_06,2023-12-05_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 bulkscore=0 spamscore=0 adultscore=0 suspectscore=0 clxscore=1015 impostorscore=0 malwarescore=0 priorityscore=1501 mlxscore=0 mlxlogscore=389 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2312060074 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 06, 2023 at 10:01:18AM +0100, Alexander Gordeev wrote: > On Tue, Dec 05, 2023 at 06:32:52PM +0100, Claudio Imbrenda wrote: > ... > > + do { > > + value = __atomic64_or_barrier(PGSTE_PCL_BIT, ptr); > > Would it make sense to cpu_relax() here, e.g with a follow-up patch? No, because cpu_relax() is a no-op on our architecture (besides that it translates to barrier(); but __atomic64_or_barrier() obviously comes also with barrier() semantics). We used to do diag 0x44 with cpu_relax() but that caused many performance problems, therefore we removed diag 0x44 completely from the kernel quite some time ago. See also commit 1b68ac8678a8 ("s390: remove last diag 0x44 caller").