From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by mx.groups.io with SMTP id smtpd.web12.32315.1612178217856773341 for ; Mon, 01 Feb 2021 03:16:58 -0800 Authentication-Results: mx.groups.io; dkim=missing; spf=pass (domain: huawei.com, ip: 185.176.79.56, mailfrom: jonathan.cameron@huawei.com) Received: from fraeml743-chm.china.huawei.com (unknown [172.18.147.200]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4DTlc62gtKz67jjZ; Mon, 1 Feb 2021 19:10:46 +0800 (CST) Received: from lhreml710-chm.china.huawei.com (10.201.108.61) by fraeml743-chm.china.huawei.com (10.206.15.224) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Mon, 1 Feb 2021 12:16:52 +0100 Received: from localhost (10.47.76.76) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2106.2; Mon, 1 Feb 2021 11:16:51 +0000 Date: Mon, 1 Feb 2021 11:16:07 +0000 From: "Jonathan Cameron" To: Vijayenthiran Subramanian CC: , Jonathan Cameron via groups.io , , , Sami Mujawar , "Thomas Abraham" Subject: Re: [edk2-devel] [edk2-platforms] [PATCH v1 2/3] Platform/ARM/SgiPkg: Add HMAT ACPI table for RdN1EdgeX2 Message-ID: <20210201111607.00007019@Huawei.com> In-Reply-To: References: <1611841351-5039-1-git-send-email-vijayenthiran.subramaniam@arm.com> <1611841351-5039-3-git-send-email-vijayenthiran.subramaniam@arm.com> <165E70A6BEEFF3E5.24597@groups.io> <20210129094940.00004799@Huawei.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; i686-w64-mingw32) MIME-Version: 1.0 X-Originating-IP: [10.47.76.76] X-ClientProxiedBy: lhreml703-chm.china.huawei.com (10.201.108.52) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit On Fri, 29 Jan 2021 17:11:03 +0000 Vijayenthiran Subramanian wrote: Hi Vijayenthiran, .... > > > > + // Memory Proximity Domain > > > > + { > > > > + EFI_ACPI_6_3_HMAT_STRUCTURE_MEMORY_PROXIMITY_DOMAIN_ATTRIBUTES_INIT ( > > > > + 1, 0x0, 0x0), > > > > + EFI_ACPI_6_3_HMAT_STRUCTURE_MEMORY_PROXIMITY_DOMAIN_ATTRIBUTES_INIT ( > > > > + 1, 0x1, 0x1), > > > > + }, > > > > + > > > > + // Latency Info > > > > + EFI_ACPI_6_3_HMAT_STRUCTURE_SYSTEM_LOCALITY_LATENCY_AND_BANDWIDTH_INFO_INIT ( > > > > + 0, 0, INITATOR_PROXIMITY_DOMAIN_CNT, TARGET_PROXIMITY_DOMIAIN_CNT, 100), > > > > + { > > > > + {0, 1}, {0, 1}, > > > > + { > > > > + 10, 20, > > > > + 20, 10, > > > > + } > > > > + }, > > > > Hi, > > > > Now either you have a very odd machine in which latencies are round numbers that happen > > to look like the values in SLIT or ... ? > > > > HMAT has very carefully defined real world units to overcome the fact that there > > was no standard scaling etc for SLIT. It is not a good idea to put tables out > > there which don't do this right as someone may copy this for a real system > > and we end up with HMAT being roughly as useless for performance prediction as > > SLIT is. That is not something I would want to see. > > > > Jonathan > > This patch is for a platform that is modelled and not for an actual board. So > the latencies are hypothetical but ensure that the typical latency between two > chips is represented. These tables are not expected to be copied for another > platform without understanding what these values mean. Such a copy, without > understanding what is being copied, would be an error in judgement on the part > of the person doing it. The commit message of this patch (in v2) can be updated > to exercise caution on reusing these values. > > [1]: https://developer.arm.com/products/system-design/fixed-virtual-platforms No one reads commit messages. So if you want to avoid people copying them put a comment in the actual file. Or just make up some more plausible numbers :) All we really need here is to avoid giving the impression that copying numbers from SLIT is valid. Jonathan > > Best Regards, > Vijayenthiran > > > > > > > + > > > > + // Memory Side Cache > > > > + EFI_ACPI_6_3_HMAT_STRUCTURE_MEMORY_SIDE_CACHE_INFO_INIT ( > > > > + 0x0, SIZE_8MB, > > > > + HMAT_STRUCTURE_MEMORY_SIDE_CACHE_INFO_CACHE_ATTRIBUTES_INIT ( > > > > + 1, > > > > + 1, > > > > + 2, > > > > + 2, > > > > + 64 // 64 bytes cache line length > > > > + ), > > > > + 0), > > > > + > > > > + EFI_ACPI_6_3_HMAT_STRUCTURE_MEMORY_SIDE_CACHE_INFO_INIT ( > > > > + 0x1, SIZE_8MB, > > > > + HMAT_STRUCTURE_MEMORY_SIDE_CACHE_INFO_CACHE_ATTRIBUTES_INIT ( > > > > + 1, > > > > + 1, > > > > + 2, > > > > + 2, > > > > + 64 // 64 bytes cache line length > > > > + ), > > > > + 0), > > > > +}; > > > > + > > > > +VOID* CONST ReferenceAcpiTable = &Hmat; > > > > > > > > > > > > > > > > > >