From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-002e3701.pphosted.com (mx0b-002e3701.pphosted.com [148.163.143.35]) by mx.groups.io with SMTP id smtpd.web11.57253.1584981523993597200 for ; Mon, 23 Mar 2020 09:38:44 -0700 Authentication-Results: mx.groups.io; dkim=missing; spf=pass (domain: hpe.com, ip: 148.163.143.35, mailfrom: prvs=03516d818c=brian.johnson@hpe.com) Received: from pps.filterd (m0134424.ppops.net [127.0.0.1]) by mx0b-002e3701.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 02NGVMER014622; Mon, 23 Mar 2020 16:38:43 GMT Received: from g4t3426.houston.hpe.com (g4t3426.houston.hpe.com [15.241.140.75]) by mx0b-002e3701.pphosted.com with ESMTP id 2ywcn3ytn7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 23 Mar 2020 16:38:43 +0000 Received: from g4t3433.houston.hpecorp.net (g4t3433.houston.hpecorp.net [16.208.49.245]) by g4t3426.houston.hpe.com (Postfix) with ESMTP id 8E75A65; Mon, 23 Mar 2020 16:38:42 +0000 (UTC) Received: from [16.214.193.48] (unknown [16.214.193.48]) by g4t3433.houston.hpecorp.net (Postfix) with ESMTP id 67A0D47; Mon, 23 Mar 2020 16:38:41 +0000 (UTC) Subject: Re: [edk2-devel] [RFC][PATCH v1] UefiCpuPkg/MpInitLib DXE: Reduce AP status check interval To: devel@edk2.groups.io, ray.ni@intel.com, Laszlo Ersek , "Wu, Hao A" , "rfc@edk2.groups.io" Cc: "Dong, Eric" , "Kinney, Michael D" , "Zeng, Star" References: <20200313132229.7628-1-hao.a.wu@intel.com> <6bf39348-1fcb-fd14-bc16-dd026ed200ad@redhat.com> <734D49CCEBEEF84792F5B80ED585239D5C49B8BF@SHSMSX104.ccr.corp.intel.com> <734D49CCEBEEF84792F5B80ED585239D5C4A88A9@SHSMSX104.ccr.corp.intel.com> From: "Brian J. Johnson" Message-ID: <6ebcd2e2-22bb-ce6d-ac94-cd6cf26c0462@hpe.com> Date: Mon, 23 Mar 2020 11:38:40 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <734D49CCEBEEF84792F5B80ED585239D5C4A88A9@SHSMSX104.ccr.corp.intel.com> X-HPE-SCL: -1 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.645 definitions=2020-03-23_06:2020-03-23,2020-03-23 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 mlxlogscore=999 impostorscore=0 mlxscore=0 spamscore=0 malwarescore=0 suspectscore=0 phishscore=0 priorityscore=1501 clxscore=1011 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003230089 Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit On 3/23/20 9:37 AM, Ni, Ray wrote: >>> Laszlo, >>> Adding a PCD means platform integrators need to consider which value to set. >>> Most of the time, they may just use the default PCD value. >>> Then, why not we add the PCD later when a real case is met? >> >> The patch changes existent behavior; it is not for a newly introduced >> feature. >> >> Because most platforms are not in the edk2 tree, we don't know what >> platforms could be regressed by increasing the polling frequency >> tenfold. (And remember that the polling action has O(n) cost, where "n" >> is the logical processor count.) >> >> Under your suggestion, the expression "real case is met" amounts to >> "someone reports a regression" (possibly after the next stable tag, >> even). I don't think that's a good idea. >> In particular, the patch is motivated by RegisterCpuFeaturesLib -- the >> CpuFeaturesInitialize() function -- on some platform(s) that Hao uses. >> But there are platforms that don't use RegisterCpuFeaturesLib, and still >> use MpInitLib. > > OK. I agree with your suggestion. Thank you. I agree with Laszlo: MP initialization is tricky to scale, and platform dependent. My group builds real machines with thousands of APs, and we have had to do various tweaks to the MP init. code. Having a PCD to adjust this timeout will be very useful. Thanks, -- Brian J. Johnson Enterprise X86 Lab Hewlett Packard Enterprise brian.johnson@hpe.com