RFR: 8264412: AArch64: CPU description should refer DMI [v2]

Gerard Ziemski gziemski at openjdk.java.net
Mon Apr 5 18:23:24 UTC 2021


On Wed, 31 Mar 2021 13:23:44 GMT, Yasumasa Suenaga <ysuenaga at openjdk.org> wrote:

>> `jdk.CPUInformation` event on AArch64 has valid CPU description in [JDK-8262491](https://bugs.openjdk.java.net/browse/JDK-8262491), however it does not work on UEFI booted machine.
>> 
>> [JDK-8262491](https://bugs.openjdk.java.net/browse/JDK-8262491) refers device tree to get board name, however it does not exist on UEFI. We need to refer DMI.
>> However we need to have root privilege, so we refer /sys/devices/virtual/dmi/id to avoid it.
>> 
>> We can get board name from /sys/devices/virtual/dmi/id/board_name, but some machine set empty string to it. So we will refer /sys/devices/virtual/dmi/id/product_name as a fallback.
>> 
>> For example, we can get following CPU description on AWS A1 instance after this change:
>> 
>> jdk.CPUInformation {
>>   startTime = 05:28:24.506
>>   cpu = "AArch64"
>>   description = "AArch64 a1.2xlarge  0x41:0x0:0xd08:3, simd, crc, aes, sha1, sha256"
>>   sockets = 8
>>   cores = 8
>>   hwThreads = 8
>> }
>
> Yasumasa Suenaga has updated the pull request incrementally with one additional commit since the last revision:
> 
>   refactoring

src/hotspot/os_cpu/linux_aarch64/vm_version_linux_aarch64.cpp line 183:

> 181:     // (e.g. /sys/devices/virtual/dmi/id/board_name)
> 182:     if ((read_sz > 0) && (*buf != '\n')) {
> 183:       buf[read_sz - 1] = '\0';

Personally, I would move it after we process the characters. It logically belongs at the end of the processing code, just before we return "true".

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PR: https://git.openjdk.java.net/jdk/pull/3259


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