Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756486AbdCGXpY (ORCPT ); Tue, 7 Mar 2017 18:45:24 -0500 Received: from mx0a-00010702.pphosted.com ([148.163.156.75]:38545 "EHLO mx0b-00010702.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756585AbdCGXpW (ORCPT ); Tue, 7 Mar 2017 18:45:22 -0500 X-Greylist: delayed 4120 seconds by postgrey-1.27 at vger.kernel.org; Tue, 07 Mar 2017 18:42:46 EST From: Julia Cartwright To: , CC: Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur , Paul Gortmaker , Steven Rostedt , , John Ogness Subject: [PATCH RT 4/9] x86/mm/cpa: avoid wbinvd() for PREEMPT Date: Tue, 7 Mar 2017 16:32:54 -0600 Message-ID: <20dc04833e45cf6a3b5fcee0f357e4e829a78b8a.1488919535.git.julia@ni.com> X-Mailer: git-send-email 2.11.1 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-03-07_18:,, signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1702020001 definitions=main-1703070176 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-03-07_18:,, signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=30 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=30 reason=mlx scancount=1 engine=8.0.1-1702020001 definitions=main-1703070176 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1602 Lines: 46 4.1.38-rt46-rc1 stable review patch. If you have any objection to the inclusion of this patch, let me know. --- 8< --- 8< --- 8< --- From: John Ogness Although wbinvd() is faster than flushing many individual pages, it blocks the memory bus for "long" periods of time (>100us), thus directly causing unusually large latencies on all CPUs, regardless of any CPU isolation features that may be active. For 1024 pages, flushing those pages individually can take up to 2200us, but the task remains fully preemptible during that time. Cc: stable-rt@vger.kernel.org Acked-by: Peter Zijlstra (Intel) Signed-off-by: John Ogness Signed-off-by: Sebastian Andrzej Siewior (cherry picked from commit 9e539d7327b265c639c859ab1fb7d3699ba0cb19) Signed-off-by: Julia Cartwright --- arch/x86/mm/pageattr.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 2dd9b3ad3bb5..4314b9103ff0 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -209,7 +209,15 @@ static void cpa_flush_array(unsigned long *start, int numpages, int cache, int in_flags, struct page **pages) { unsigned int i, level; +#ifdef CONFIG_PREEMPT + /* + * Avoid wbinvd() because it causes latencies on all CPUs, + * regardless of any CPU isolation that may be in effect. + */ + unsigned long do_wbinvd = 0; +#else unsigned long do_wbinvd = cache && numpages >= 1024; /* 4M threshold */ +#endif BUG_ON(irqs_disabled()); -- 2.11.1