Guru3D.com
  • HOME
  • NEWS
    • Channels
    • Archive
  • DOWNLOADS
    • New Downloads
    • Categories
    • Archive
  • GAME REVIEWS
  • ARTICLES
    • Rig of the Month
    • Join ROTM
    • PC Buyers Guide
    • Guru3D VGA Charts
    • Editorials
    • Dated content
  • HARDWARE REVIEWS
    • Videocards
    • Processors
    • Audio
    • Motherboards
    • Memory and Flash
    • SSD Storage
    • Chassis
    • Media Players
    • Power Supply
    • Laptop and Mobile
    • Smartphone
    • Networking
    • Keyboard Mouse
    • Cooling
    • Search articles
    • Knowledgebase
    • More Categories
  • FORUMS
  • NEWSLETTER
  • CONTACT

New Reviews
Crucial T700 PCIe 5.0 NVMe SSD Review - 12GB/s
Sapphire Radeon RX 7600 PULSE review
Gainward GeForce RTX 4060 Ti GHOST review
Radeon RX 7600 review
ASUS GeForce RTX 4060 Ti TUF Gaming review
MSI GeForce RTX 4060 Ti Gaming X TRIO review
GeForce RTX 4060 Ti 8GB (FE) review
Corsair 2000D RGB Airflow Mini-ITX - PC chassis review
ASUS PG27AQDM Review - 240Hz 1440p OLED monitor
MSI MAG X670E Tomahawk WiFi review

New Downloads
GeForce 535.98 WHQL driver download
CPU-Z download v2.06
AMD Radeon Software Adrenalin 23.5.1 WHQL download
GeForce 532.03 WHQL driver download
AMD Chipset Drivers Download 5.05.16.529
Corsair Utility Engine Download (iCUE) Download v5.1 (5.1.1114 )
CrystalDiskInfo 9.0.0 RC3 Download
Intel ARC graphics Driver Download Version: 31.0.101.4369
Display Driver Uninstaller Download version 18.0.6.4
HWiNFO Download v7.46


New Forum Topics
Replacing the RX6600 XT NVIDIA GeForce Game Ready 535.98 WHQL Download & Discussion NVIDIA Profile Inspector 2.4.0.4 Review: Crucial T700 PCIe 5.0 NVMe 2TB SSD going for 12GB/s Various games passed/failed and benchmarks under MS-DOS on new GeForce RTX 4090 AMD Software: 23.Q2.1 iCafe edition - Driver Download and Discussion Motherboard Choice for a 13700k build NVIDIA Introduces G-SYNC Ultra Low Motion Blur 2 (ULMB 2) for Enhanced Motion Clarity in Competitive Gaming Nvidia shows signs ... CPU Virtualization on or off?




Guru3D.com » News » AMD: Windows Thread Scheduler is operating properly for Ryzen

AMD: Windows Thread Scheduler is operating properly for Ryzen

by Hilbert Hagedoorn on: 03/14/2017 08:52 AM | source: | 124 comment(s)
AMD: Windows Thread Scheduler is operating properly for Ryzen

AMD has investigated the reports of thread scheduling issues and found that "the Windows 10 thread scheduler is operating properly for "Zen," and we do not presently believe there is an issue with the scheduler adversely utilizing the logical and physical configurations of the architecture." They also talk SMT and power plans.

So there will not be an easy fix for the low 1080p game performance issues then. Hence you should not expect a Windows 10 performance patch. AMD tested Windows 10 and Windows 7 and they "do not believe there is an issue with scheduling differences between the two versions of Windows."

AMD: 

While these findings have been great to read, we are just getting started! The AMD Ryzen™ processor and AM4 Platform both have room to grow, and we wanted to take a few minutes to address some of the questions and comments being discussed across the web.

Thread Scheduling

We have investigated reports alleging incorrect thread scheduling on the AMD Ryzen™ processor. Based on our findings, AMD believes that the Windows® 10 thread scheduler is operating properly for “Zen,” and we do not presently believe there is an issue with the scheduler adversely utilizing the logical and physical configurations of the architecture.

As an extension of this investigation, we have also reviewed topology logs generated by the Sysinternals Coreinfo utility. We have determined that an outdated version of the application was responsible for originating the incorrect topology data that has been widely reported in the media. Coreinfo v3.31 (or later) will produce the correct results.

Finally, we have reviewed the limited available evidence concerning performance deltas between Windows® 7 and Windows® 10 on the AMD Ryzen™ CPU. We do not believe there is an issue with scheduling differences between the two versions of Windows.  Any differences in performance can be more likely attributed to software architecture differences between these OSes.

Going forward, our analysis highlights that there are many applications that already make good use of the cores and threads in Ryzen, and there are other applications that can better utilize the topology and capabilities of our new CPU with some targeted optimizations. These opportunities are already being actively worked via the AMD Ryzen™ dev kit program that has sampled 300+ systems worldwide.

Above all, we would like to thank the community for their efforts to understand the Ryzen processor and reporting their findings. The software/hardware relationship is a complex one, with additional layers of nuance when preexisting software is exposed to an all-new architecture. We are already finding many small changes that can improve the Ryzen performance in certain applications, and we are optimistic that these will result in beneficial optimizations for current and future applications.

Power Plans

Users may have heard that AMD recommends the High Performance power plan within Windows® 10 for the best performance on Ryzen, and indeed we do. We recommend this plan for two key reasons: 

  1. Core Parking OFF: Idle CPU cores are instantaneously available for thread scheduling. In contrast, the Balanced plan aggressively places idle CPU cores into low power states. This can cause additional latency when un-parking cores to accommodate varying loads.
  2. Fast frequency change: The AMD Ryzen™ processor can alter its voltage and frequency states in the 1ms intervals natively supported by the “Zen” architecture. In contrast, the Balanced plan may take longer for voltage and frequency (V/f) changes due to software participation in power state changes.

In the near term, we recommend that games and other high-performance applications are complemented by the High Performance plan. By the first week of April, AMD intends to provide an update for AMD Ryzen™ processors that optimizes the power policy parameters of the Balanced plan to favor performance more consistent with the typical usage models of a desktop PC.

Simultaneous Multi-threading (SMT)

Finally, we have investigated reports of instances where SMT is producing reduced performance in a handful of games. Based on our characterization of game workloads, it is our expectation that gaming applications should generally see a neutral/positive benefit from SMT. We see this neutral/positive behavior in a wide range of titles, including: Arma® 3, Battlefield™ 1, Mafia™ III, Watch Dogs™ 2, Sid Meier’s Civilization® VI, For Honor™, Hitman™, Mirror’s Edge™ Catalyst and The Division™. Independent 3rd-party analyses have corroborated these findings.

For the remaining outliers, AMD again sees multiple opportunities within the codebases of specific applications to improve how this software addresses the “Zen” architecture. We have already identified some simple changes that can improve a game’s understanding of the "Zen" core/cache topology, and we intend to provide a status update to the community when they are ready.







« Analyst Predicts Weak Market for Samsung S8 Due to iPhone 8 · AMD: Windows Thread Scheduler is operating properly for Ryzen · AMD Ryzen 7 have a Temperature 20 Degree C Reporting Offset »

25 pages « < 22 23 24 25


sykozis



Posts: 22470
Joined: 2008-07-14

#5407564 Posted on: 03/16/2017 06:23 AM
Ok, I am not a computer engineer but how can one physical core contain one physical thread and one logical? To my understanding it is one physical core with two logical threads.


lol..... Your understanding is correct, sort of. Maybe you're just stating it incorrectly.

The OS only "sees" logical cores, not physical. In the case of Intel processors, Windows can't differentiate between physical cores and HTT-enabled logical cores.

With Intel's HyperThreading, it's 2 logical cores for every 1 physical core.

Chillin
Senior Member



Posts: 6814
Joined: 2006-01-18

#5407571 Posted on: 03/16/2017 06:35 AM
Here's what Anandtech had to say:

The silicon design consists of two core complexes (CCX) of four cores apiece, and each with 8MB of L3 cache that is an exclusive victim cache. One of the suggestions regarding Ryzen 7’s performance was about thread migration and scheduling on the core design, especially as core-to-core latency varies depending on where the cores are located (and there’s a jump between CCXes). Despite the use of AMD’s new Infinity Fabric, which is ultimately a superset of HyperTransport, there is still a slightly longer delay jumping over that CCX boundary, although the default Windows scheduler knows how to manage that boundary as demonstrated by Allyn at PCPerspective earlier this week.



schmidtbag
Senior Member



Posts: 7428
Joined: 2012-11-10

#5407769 Posted on: 03/16/2017 03:24 PM
Ok, I am not a computer engineer but how can one physical core contain one physical thread and one logical? To my understanding it is one physical core with two logical threads.

The terminology is a bit confusing and I probably didn't really phrase my sentence correctly. Technically, a single HT/SMT-enabled core has 2 logical threads with only one physical. The issue is there's not really a quick and easy way to distinguish the additional thread(s) created by HT or SMT. In the eyes of the OS, a logical thread can be either a dedicated physical core, or, it can be a created by HT or SMT. For example:
http://i.imgur.com/xV5iOfv.png?1
But in conversation, not all logical threads are directly associated to physical cores (even though they are still processed on a physical core...)
That being said, when referring to threads, it's easier to just say "physical cores" when referring to any thread not produced by HT/SMT thread, and say "logical thread" when implying the inverse.

So yeah, it's technically wrong, but people tend to get the gist of what was implied. I have yet to encounter anyone who could phrase it more clearly. Generally, it doesn't really matter enough. Personally I think the easier way to phrase it is "primary threads" and "secondary threads", since the HT/SMT generated threads are run separately from the "physical theads". But, good luck convincing everyone to jump on board with that.

PrMinisterGR
Senior Member



Posts: 8103
Joined: 2014-09-27

#5407800 Posted on: 03/16/2017 04:09 PM
Meh, the LLVM-related patches show me that it's most likely compiler issues because applications load the Bulldozer profile for it. Even with compiler optimizations, it will never be as fast as a 5GHz Kaby in single-threaded, but with them it will probably make the gap small enough for most people not to care at all.

25 pages « < 22 23 24 25


Post New Comment
Click here to post a comment for this news story on the message forum.


Guru3D.com © 2023