MSI offers Re-Size BAR function ( SAM ) that works cross platform Nvidia / AMD 5000 chipset

[varkanoid]

The question is if the new games will be able to take advantage of this feature or it is something that gives you extra FPS sometimes if the game wants that.
I also noticed it improves the min FPS in some games so that is even better.

It will work on any game. The results however are another question.

Its not reliant on a game taking advantage its the way the CPU interacts with the GPU's VRAM. Nothing really to do with a game. It basically removes a limitation in the hardware interaction.

 

[Hotwired]

One of the AMD engineers (aka not a reddit pleb) has been doing some replies lately.

https://old.reddit.com/r/Amd/comments/kr52mf/phoronix_radeon_linux_drivers_now_only_officially/

https://old.reddit.com/r/Amd/comments/kr6z9h/smart_access_memory_on_my_3600_5700_xt/

Of particular note is this:

the short answer, Zen3 has architectural improvements that make the resizable BAR feature work better and provide FPS gains.

Other CPUs may use PCIE standard (Resizable BAR) feature, but it may not give any significant perf lift. Other unsupported CPU/GPU/platform combinations may experience issues with the large allocation. Some platforms behave poorly with Above 4G enabled due to many factors.

So as has been suspected, getting Resizable BAR enabled without proper support (such as AMDs SAM) can be done, however it doesn't guarantee any benefits at all.

Reminder that Nvidia rushed out a "me too" note to the tech channels the moment they heard of this and and are yet to prove they can support Resizable Bar in a useful way.

The benefits are small and this is an AMD engineer saying Zen3 actually matters to get them.

 

[Chuk_Chuk]

One of the AMD engineers (aka not a reddit pleb) has been doing some replies lately.

https://old.reddit.com/r/Amd/comments/kr52mf/phoronix_radeon_linux_drivers_now_only_officially/

https://old.reddit.com/r/Amd/comments/kr6z9h/smart_access_memory_on_my_3600_5700_xt/

Of particular note is this:



So as has been suspected, getting Resizable BAR enabled without proper support (such as AMDs SAM) can be done, however it doesn't guarantee any benefits at all.

Reminder that Nvidia rushed out a "me too" note to the tech channels the moment they heard of this and and are yet to prove they can support Resizable Bar in a useful way.

The benefits are small and this is an AMD engineer saying Zen3 actually matters to get them.

I knew there was a difference somewhere.

It would be interested to do a comparison between Zen 2 and 3 to see how big of a difference this is. Someone (maybe AMD) mentioned that games needed to be coded to take full advantage of this so i wonder if any gap will widen in such situation. If AMD is smart they will be getting developers on board with this ASAP.

 

[Grim5]

One of the AMD engineers (aka not a reddit pleb) has been doing some replies lately.

https://old.reddit.com/r/Amd/comments/kr52mf/phoronix_radeon_linux_drivers_now_only_officially/

https://old.reddit.com/r/Amd/comments/kr6z9h/smart_access_memory_on_my_3600_5700_xt/

Of particular note is this:



So as has been suspected, getting Resizable BAR enabled without proper support (such as AMDs SAM) can be done, however it doesn't guarantee any benefits at all.

Reminder that Nvidia rushed out a "me too" note to the tech channels the moment they heard of this and and are yet to prove they can support Resizable Bar in a useful way.

The benefits are small and this is an AMD engineer saying Zen3 actually matters to get them.

Reminder that Nvidia is working on a specific implementation of it rather than the me too that Intel did which showed almost no difference except for a couple games where for some reason Intel bar showed bigger gains than amd Sam

 

[EastCoastHandle]

Reminder that Nvidia is working on a specific implementation of it rather than the me too that Intel did which showed almost no difference except for a couple games where for some reason Intel bar showed bigger gains than amd Sam

Nvidia did do a "Me too" when they tried to downplay SAM as nothing more then resizable bar. And said they had it working as well. But never showcased anything from it. Not even a sneak peak.

From NVIDIA, re:SAM: “The capability for resizable BAR is part of the PCI Express spec. NVIDIA hardware supports this functionality and will enable it on Ampere GPUs through future software updates. We have it working internally and are seeing similar performance results."

https://twitter.com/GamersNexus/status/1327006795253084161?ref_src=twsrc^tfw|twcamp^tweetembed|twterm^1327006795253084161|twgr^|twcon^s1_&ref_url=https://wccftech.com/nvidia-confirms-ampere-geforce-rtx-30-gpus-to-get-its-own-smart-access-memory-sam-tech/

 

[Mesai]

Nvidia did do a "Me too" when they tried to downplay SAM as nothing more then resizable bar. And said they had it working as well. But never showcased anything from it. Not even a sneak peak.

Nvidia are working on RTX IO so wouldn’t surprise me if they did look at resizable BAR and put it aside to instead focus on RTX IO as a more valuable technology.

 

[EastCoastHandle]

Nvidia are working on RTX IO so wouldn’t surprise me if they did look at resizable BAR and put it aside to instead focus on RTX IO as a more valuable technology.

When it comes from that company don't hold your breath.

 

[Chuk_Chuk]

Nvidia are working on RTX IO so wouldn’t surprise me if they did look at resizable BAR and put it aside to instead focus on RTX IO as a more valuable technology.

RTX IO is based off of MS direct storage and isn't released till later this year. I doubt it took that much work/resources.

 

[BS Dave]

https://overclock3d.net/reviews/gpu..._on_zen_2_cpus_-_the_power_of_resizable_bar/1

seems to work just fine without Zen 3

 

[Roguey000]

I guess resizable bar wont work with older gpus such as the 20/10 series?

 

[Mesai]

RTX IO is based off of MS direct storage and isn't released till later this year. I doubt it took that much work/resources.

Same could be said about SAM; just because the base tech exists, doesn't mean AMD or Nvidia flip a switch and it works. I think you underestimate the complexity of implementing a broadly used technology i.e. something that isn't implemented per game.

Yes, it's based on MS direct storage but it's a fundamental change to how game assets are loaded to the GPU, and would require extensive testing across multiple applications to ensure that it doesn't negatively impact performance. Resizable BAR would have the same requirements.

 

[BS Dave]

I guess resizable bar wont work with older gpus such as the 20/10 series?

who knows? People are saying they are seeing uplift on 5700 series, and AMD didn't make a big song and dance about SAM when they were released.

If AMD release support back to VEGA then maybe Nvidia will feel pressured to do the same?

 

[Chuk_Chuk]

Same could be said about SAM; just because the base tech exists, doesn't mean AMD or Nvidia flip a switch and it works. I think you underestimate the complexity of implementing a broadly used technology i.e. something that isn't implemented per game.

Yes, it's based on MS direct storage but it's a fundamental change to how game assets are loaded to the GPU, and would require extensive testing across multiple applications to ensure that it doesn't negatively impact performance. Resizable BAR would have the same requirements.

I never implied anything that you seem to be assuming about my post. What i was saying is that MS did most of the hardwork to get the tech working.

Also AMD the smaller company has managed to do both with far less resources than Nvidia. Assuming that direct storage is a DX12 ultimate feature and that RDNA 2 fully supports DX 12. In reference to your original comment.

 

[Grim5]

Nvidia are working on RTX IO so wouldn’t surprise me if they did look at resizable BAR and put it aside to instead focus on RTX IO as a more valuable technology.

I don't think RTX IO is going to work until Microsoft delives the Direct Store function to Windows, which is 6 months away

 

[Grim5]

TLDR: SAM improves performance by 3% on average, resolution doesn't change anything on average

Best to test it yourself on a per game basis prior to enabling (as painful as it can be changing BIOS settings and rebooting) as some games lose up to 10% performance with SAM enabled.

 

[CAT-THE-FIFTH]

SAM tested with a Ryzen 9 3950X and an RDNA2 GPU:
https://www.overclock3d.net/reviews..._on_zen_2_cpus_-_the_power_of_resizable_bar/1

It appears to give a noticeable performance uplift with AC:Valhalla,Forza Horizon 4,RE3 and Cyberpunk 2077.

I knew there was a difference somewhere.

It would be interested to do a comparison between Zen 2 and 3 to see how big of a difference this is. Someone (maybe AMD) mentioned that games needed to be coded to take full advantage of this so i wonder if any gap will widen in such situation. If AMD is smart they will be getting developers on board with this ASAP.

It works with Zen2 - AMD CBA with Zen2,etc since they want to sell it as a feature with Zen3.

 

[CAT-THE-FIFTH]

TLDR: SAM improves performance by 3% on average, resolution doesn't change anything on average

Best to test it yourself on a per game basis prior to enabling (as painful as it can be changing BIOS settings and rebooting) as some games lose up to 10% performance with SAM enabled.

Some games lose upto 10% but others gain upto 20% it appears.

Spoiler

 

[Grim5]

Some games lose upto 10% but others gain upto 20% it appears.

Spoiler

thats why I said it's best for the user to test performance before they just leave it enabled.

would be nice if you guys could keep a list of games that gain/lose performance so that users know when to use it and when not to without wasting time themselves

 

[CAT-THE-FIFTH]

thats why I said it's best for the user to test performance before they just leave it enabled.

would be nice if you guys could keep a list of games that gain/lose performance so that users know when to use it and when not to without wasting time themselves

It also depends on CPU too. Zen2 seems to gain in Cyberpunk 2077 with SAM enabled but not Zen3,unless OFC its also dependent on the scene tested in the game.

 

[Mesai]

I never implied anything that you seem to be assuming about my post. What i was saying is that MS did most of the hardwork to get the tech working.

Also AMD the smaller company has managed to do both with far less resources than Nvidia. Assuming that direct storage is a DX12 ultimate feature and that RDNA 2 fully supports DX 12. In reference to your original comment.

You said "I doubt it took that much work/resources", which means you think that RTX IO and MS DirectStorage are the same thing.

DS, as you mentioned, is part of the DX12 API and is therefore available to anyone who uses it (AMD and Nvidia will optimise how it's used via their drivers). It relies on you having a high-end SSD to support it as the majority of drives aren't fast enough to manage batching and parallel requests, which is what DS enables. None of this changes the foundational process of how the CPU, RAM and GPU interact with those assets - files still get loaded to the RAM to be decompressed by the CPU and then passed to the GPU, etc., DS just lets you do this way more effeciently and with better throughput.

RTX IO leverages DS, but it changes the foundational process in that it cuts out the middle man (CPU and RAM) and loads the assets to the VRAM as the GPU is much better at decompression than the CPU (more cores). There are several benefits to this.

Nvidia have an article on it (with diagrams): https://www.nvidia.com/en-gb/geforce/news/rtx-io-gpu-accelerated-storage-technology/

I don't think RTX IO is going to work until Microsoft delives the Direct Store function to Windows, which is 6 months away

Yep, it requires the DirectStorage API to function, so it'll only be available once that has been released to the general public.