Re: Regarding report amount of usable graphics memory

Re: Regarding report amount of usable graphics memory

[Daniel Vetter]

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On 27/11/2013 06:41, Zhang, Jianhong wrote:
>
> Hi Daniel,
>
> 1.On Harris Beach, we always see this report as below even we set 
> different TOLUD size, such as1GB, 1.5GB, 2GB and 3GB :
>
> [drm] Memory usable by graphics device = 2048M
>
>        2.   Based on the implementation below, it shouldn't matter 
> with TOLUD size.
>
>              DRM_INFO("Memory Usable by graphics device = %dM\n", 
> dev_priv->mm.gtt->gtt_total_entries >> 8);
>
> Please confirm if this is the case:
>
> If RAM is 4GB, it will report 2048M as the usable memory by graphics 
> device.
>
> This is the max size that graphics could use,  and it shouldn't change 
> based on TOLUD size.
>
Yeah. But the real question is what do you need this for exactly? Also, 
cc'ing relevant internal mailing lists.
-Daniel
>
> Best regards,
>
> Jianhong
>

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Re: Regarding report amount of usable graphics memory

[Zhang, Jianhong]

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Hi Daniel,

I'm working on a sighting that filed by PCCG. It complains that "Memory usable by graphics device = 2048M" even TOLUD is 1.5GB.
>From the formula, looks like it shouldn't affected by TOLUD size, but I need the confirmation to resolve the sighting as expected.

Best regards,
Jianhong

From: Vetter, Daniel
Sent: Wednesday, November 27, 2013 12:07 AM
To: Zhang, Jianhong; intel-gfx@lists.freedesktop.org
Subject: Re: Regarding report amount of usable graphics memory

On 27/11/2013 06:41, Zhang, Jianhong wrote:
Hi Daniel,


1.       On Harris Beach, we always see this report as below even we set different TOLUD size, such as1GB, 1.5GB, 2GB and 3GB :

[drm] Memory usable by graphics device = 2048M

       2.   Based on the implementation below, it shouldn't matter with TOLUD size.
             DRM_INFO("Memory Usable by graphics device = %dM\n", dev_priv->mm.gtt->gtt_total_entries >> 8);

Please confirm if this is the case:
If RAM is 4GB, it will report 2048M as the usable memory by graphics device.
This is the max size that graphics could use,  and it shouldn't change based on TOLUD size.

Yeah. But the real question is what do you need this for exactly? Also, cc'ing relevant internal mailing lists.
-Daniel


Best regards,
Jianhong



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Re: Regarding report amount of usable graphics memory

[Chris Wilson]

On Wed, Nov 27, 2013 at 06:03:16PM +0000, Zhang, Jianhong wrote:
>    Hi Daniel,
> 
>     
> 
>    I’m working on a sighting that filed by PCCG. It complains that “Memory
>    usable by graphics device = 2048M” even TOLUD is 1.5GB.
> 
>    From the formula, looks like it shouldn’t affected by TOLUD size, but I
>    need the confirmation to resolve the sighting as expected.

Perhaps what they mean is that we always program the GTT to the maximum
possible size irrespective of the number of physical pages present in
the system. (Note that TOLUD is itself irrelevant since the GPU is not
restricted to lower memory.) As you have seen what we report is simply
what the hardware is programmed to, which is orthogonal to the amount of
memory present on the system (and so there is no conflict in reporting
that the GPU could address up to 2GiB of pages even if there is only
1GiB of RAM installed).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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