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Wed, 18 Nov 2020 19:35:51 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 0AIJZk9b020150; Wed, 18 Nov 2020 19:35:50 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userp3020.oracle.com with ESMTP id 34ts0sqqwr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 18 Nov 2020 19:35:50 +0000 Received: from abhmp0003.oracle.com (abhmp0003.oracle.com [141.146.116.9]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 0AIJZbql027868; Wed, 18 Nov 2020 19:35:37 GMT Received: from linux.home (/92.157.91.83) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 18 Nov 2020 11:35:37 -0800 Subject: Re: [RFC][PATCH v2 00/21] x86/pti: Defer CR3 switch to C code To: Borislav Petkov Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, linux-kernel@vger.kernel.org, thomas.lendacky@amd.com, jroedel@suse.de, konrad.wilk@oracle.com, jan.setjeeilers@oracle.com, junaids@google.com, oweisse@google.com, rppt@linux.vnet.ibm.com, graf@amazon.de, mgross@linux.intel.com, kuzuno@gmail.com, Mel Gorman References: <20201116144757.1920077-1-alexandre.chartre@oracle.com> <20201116201711.GE1131@zn.tnic> <44a88648-738a-4a4b-9c25-6b70000e037c@oracle.com> <20201117165539.GG5719@zn.tnic> <890f6b7e-a268-2257-edcb-5eacc7db3d8e@oracle.com> <20201117212608.GS5719@zn.tnic> <20201118112952.GB7472@zn.tnic> From: Alexandre Chartre Message-ID: <408004fa-b143-7e12-150a-0dfab12d34ee@oracle.com> Date: Wed, 18 Nov 2020 20:37:57 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201118112952.GB7472@zn.tnic> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9809 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 adultscore=0 bulkscore=0 suspectscore=0 spamscore=0 malwarescore=0 phishscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011180135 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9809 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 phishscore=0 adultscore=0 priorityscore=1501 bulkscore=0 clxscore=1015 mlxlogscore=999 malwarescore=0 mlxscore=0 spamscore=0 lowpriorityscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011180135 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/18/20 12:29 PM, Borislav Petkov wrote: > On Wed, Nov 18, 2020 at 08:41:42AM +0100, Alexandre Chartre wrote: >> Well, it looks like I wrongfully assume that KPTI was a well known performance >> overhead since it was introduced (because it adds extra page-table switches), >> but you are right I should be presenting my own numbers. > > Here's one recipe, courtesy of Mel: > > https://github.com/gormanm/mmtests > Thanks for the detailed information, I have run the test and I see the same difference as with the tools/perf and libMICRO I already sent: there's a 150% difference for getpid() with and without pti. alex. ----- # ../../compare-kernels.sh --baseline test-nopti --compare test-pti poundsyscall test test nopti pti Min 2 1.99 ( 0.00%) 5.08 (-155.28%) Min 4 1.02 ( 0.00%) 2.60 (-154.90%) Min 6 0.94 ( 0.00%) 2.07 (-120.21%) Min 8 0.81 ( 0.00%) 1.60 ( -97.53%) Min 12 0.85 ( 0.00%) 1.65 ( -94.12%) Min 18 0.82 ( 0.00%) 1.61 ( -96.34%) Min 24 0.81 ( 0.00%) 1.60 ( -97.53%) Min 30 0.81 ( 0.00%) 1.60 ( -97.53%) Min 32 0.81 ( 0.00%) 1.60 ( -97.53%) Amean 2 2.02 ( 0.00%) 5.10 *-151.83%* Amean 4 1.03 ( 0.00%) 2.61 *-151.98%* Amean 6 0.96 ( 0.00%) 2.07 *-116.74%* Amean 8 0.82 ( 0.00%) 1.60 * -96.56%* Amean 12 0.87 ( 0.00%) 1.67 * -91.73%* Amean 18 0.82 ( 0.00%) 1.63 * -97.94%* Amean 24 0.81 ( 0.00%) 1.60 * -97.41%* Amean 30 0.82 ( 0.00%) 1.60 * -96.93%* Amean 32 0.82 ( 0.00%) 1.60 * -96.56%* Stddev 2 0.02 ( 0.00%) 0.02 ( 33.78%) Stddev 4 0.01 ( 0.00%) 0.01 ( 7.18%) Stddev 6 0.01 ( 0.00%) 0.00 ( 68.77%) Stddev 8 0.01 ( 0.00%) 0.01 ( 10.56%) Stddev 12 0.01 ( 0.00%) 0.02 ( -12.69%) Stddev 18 0.01 ( 0.00%) 0.01 (-107.25%) Stddev 24 0.00 ( 0.00%) 0.00 ( -14.56%) Stddev 30 0.01 ( 0.00%) 0.01 ( 0.00%) Stddev 32 0.01 ( 0.00%) 0.00 ( 20.00%) CoeffVar 2 1.17 ( 0.00%) 0.31 ( 73.70%) CoeffVar 4 0.82 ( 0.00%) 0.30 ( 63.16%) CoeffVar 6 1.41 ( 0.00%) 0.20 ( 85.59%) CoeffVar 8 0.87 ( 0.00%) 0.39 ( 54.50%) CoeffVar 12 1.66 ( 0.00%) 0.98 ( 41.23%) CoeffVar 18 0.85 ( 0.00%) 0.89 ( -4.71%) CoeffVar 24 0.52 ( 0.00%) 0.30 ( 41.97%) CoeffVar 30 0.65 ( 0.00%) 0.33 ( 49.22%) CoeffVar 32 0.65 ( 0.00%) 0.26 ( 59.30%) Max 2 2.04 ( 0.00%) 5.13 (-151.47%) Max 4 1.04 ( 0.00%) 2.62 (-151.92%) Max 6 0.98 ( 0.00%) 2.08 (-112.24%) Max 8 0.83 ( 0.00%) 1.62 ( -95.18%) Max 12 0.89 ( 0.00%) 1.70 ( -91.01%) Max 18 0.84 ( 0.00%) 1.66 ( -97.62%) Max 24 0.82 ( 0.00%) 1.61 ( -96.34%) Max 30 0.82 ( 0.00%) 1.61 ( -96.34%) Max 32 0.82 ( 0.00%) 1.61 ( -96.34%) BAmean-50 2 2.01 ( 0.00%) 5.09 (-153.39%) BAmean-50 4 1.03 ( 0.00%) 2.60 (-152.62%) BAmean-50 6 0.95 ( 0.00%) 2.07 (-118.82%) BAmean-50 8 0.81 ( 0.00%) 1.60 ( -97.53%) BAmean-50 12 0.86 ( 0.00%) 1.66 ( -92.79%) BAmean-50 18 0.82 ( 0.00%) 1.62 ( -97.56%) BAmean-50 24 0.81 ( 0.00%) 1.60 ( -97.53%) BAmean-50 30 0.81 ( 0.00%) 1.60 ( -97.53%) BAmean-50 32 0.81 ( 0.00%) 1.60 ( -97.53%) BAmean-95 2 2.02 ( 0.00%) 5.09 (-151.87%) BAmean-95 4 1.03 ( 0.00%) 2.61 (-151.99%) BAmean-95 6 0.95 ( 0.00%) 2.07 (-117.25%) BAmean-95 8 0.81 ( 0.00%) 1.60 ( -96.72%) BAmean-95 12 0.87 ( 0.00%) 1.67 ( -91.82%) BAmean-95 18 0.82 ( 0.00%) 1.63 ( -97.97%) BAmean-95 24 0.81 ( 0.00%) 1.60 ( -97.53%) BAmean-95 30 0.81 ( 0.00%) 1.60 ( -97.00%) BAmean-95 32 0.81 ( 0.00%) 1.60 ( -96.59%) BAmean-99 2 2.02 ( 0.00%) 5.09 (-151.87%) BAmean-99 4 1.03 ( 0.00%) 2.61 (-151.99%) BAmean-99 6 0.95 ( 0.00%) 2.07 (-117.25%) BAmean-99 8 0.81 ( 0.00%) 1.60 ( -96.72%) BAmean-99 12 0.87 ( 0.00%) 1.67 ( -91.82%) BAmean-99 18 0.82 ( 0.00%) 1.63 ( -97.97%) BAmean-99 24 0.81 ( 0.00%) 1.60 ( -97.53%) BAmean-99 30 0.81 ( 0.00%) 1.60 ( -97.00%) BAmean-99 32 0.81 ( 0.00%) 1.60 ( -96.59%) test test nopti pti Duration User 150.13 432.03 Duration System 372.10 657.69 Duration Elapsed 94.17 199.27