Re: Re: [Patch RFC] ttm: nouveau accelerated on Xen pv-ops kernel

[Arvind R <arvino55@gmail.com>]

On Sun, Mar 28, 2010 at 3:50 PM, Joanna Rutkowska
<joanna@invisiblethingslab.com> wrote:
> On 03/12/2010 06:27 AM, Arvind R wrote:
>> On Thu, Mar 11, 2010 at 4:32 PM, Pekka Paalanen <pq@iki.fi> wrote:
>>> I'm adding dri-devel@ to CC, since this suggested patch touches TTM
>>> code, and none of the Nouveau code. TTM patches go via dri-devel@.
>>>
>>> Thanks.
>>>
>>>
>>> On Wed, 10 Mar 2010 18:51:21 +0530 Arvind R <arvino55@gmail.com>
>>> wrote:
>>>
>>>> Hi, Following is a simple patch that is needed in nouveau to get
>>>> accelerated X on a Xen dom0 pv_ops kernel. The kernel is
>>>> jeremy's 2.6.31.6 as of 20100222. The whole gpu tree of nouveau
>>>> (which is almost the mainline merge), was substituted into the
>>>> kernel-tree. All components of X (mesa, Xorg-server-7.5,
>>>> xf86-nouveau, libdrm) used of the same day.
>>>>
>>>> Patch: diff -Naur
>>>> nouveau-kernel.orig/drivers/gpu/drm/ttm/ttm_bo_vm.c
>>>> nouveau-kernel.new/drivers/gpu/drm/ttm/ttm_bo_vm.c ---
>>>> nouveau-kernel.orig/drivers/gpu/drm/ttm/ttm_bo_vm.c 2010-01-27
>>>> 10:19:28.000000000 +0530 +++
>>>> nouveau-kernel.new/drivers/gpu/drm/ttm/ttm_bo_vm.c  2010-03-10
>>>> 17:28:59.000000000 +0530 @@ -271,7 +271,10 @@ */
>>>>
>>>> vma->vm_private_data = bo; -       vma->vm_flags |= VM_RESERVED |
>>>> VM_IO | VM_MIXEDMAP | VM_DONTEXPAND; +       vma->vm_flags |=
>>>> VM_RESERVED | VM_MIXEDMAP | VM_DONTEXPAND; +       if
>>>> (!((bo->mem.placement & TTM_PL_MASK_MEM) & TTM_PL_FLAG_TT)) +
>>>> vma->vm_flags |= VM_IO; +       vma->vm_page_prot =
>>>> vma_get_vm_prot(vma->vm_flags); return 0; out_unref:
>>>> ttm_bo_unref(&bo);
>>>>
>> Sorry for the typo: in the last added line,
>> vma_get_vm_prot(vma->vm_flags) should be
>> vma->vm_get_page_prot(vma->vm_flags)
>>
> Arvind,
>
> I've just tried your patch (with the above correction applied). I tried
> it against the latest pvops0 kernel from xen/stable-2.6.32.x with
> back-ported nouveau code. Xen 3.4.3-rc4 hypervisor. The actual kernel is
> based on Fedora 2.6.32.10.x kernel SRPM, more specifically on the
> Michael Young's SRPM (that integrates pvops patches):
>
> http://fedorapeople.org/~myoung/dom0/src/kernel-2.6.32.10-1.2.92.xendom0.fc12.src.rpm
>
> With your patch I can get my nouveau X driver now working *without*
> NoAccel or ShadowFB settings in the xorg.conf, which was not possible
> before.
>
> I have enabled desktop composition using XRender in KDE (that runs in
> Dom0), but I see a very high "latency" in how e.g. Windows react to me
> wanting to move them on screen, or before the KDE's "Strat" menu
> appears, or when I activate the "Expose effect" (Ctrl-F8), etc. It looks
> like if the composition buffers were still kept in host memory and
> transferred to the video memory only when I want to do something with an
> object (e.g. move the window). So, e.g. after this delay at the
> beginning (e.g. after pressing Ctrl-F8) I can get smooth graphics
> effects (e.g. Expose effect), but this initial delay, that manifests
> itself before pretty much any action I take, makes the system
> practically unusable... I'm using the latest KDE 4.4.
>
> I've been wondering if you, or any other of xen-devel readers, have:
> 1) Tried the patch with some composting X Window manager in Dom0?

using ecomp (compiz port for enlightenment) on e17-git. Enabled composite.
Works with software-engine but not with xrender-engine.

> 2) Got similar results?

Works fine - no latencies I can notice - though I've tried only the default
effects settings

The sluggish/jerky keyboard/mouse in domU (SDL) consoles have also
vanished with accel-enabled X. Keypress-repeat does not work in domU.

> FWIW, when I enable ShadowFB in xorg.conf the effect no longer occurs.
> But ShadowFB disables H/W acceleration, so even though I can get rid of
> the "latency", I'm not getting smooth visual effects anymore (no smooth
> Expose effect :(
>
> Thanks,
> joanna.
>
> BTW, this is the patch I used for the recent pvops0 xen/stable-2.6.32.x:
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index 3dc8d6b..0f57125 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -271,7 +271,9 @@ int ttm_bo_mmap(struct file *filp, struct
> vm_area_struct *vma,
>         */
>
>        vma->vm_private_data = bo;
> -       vma->vm_flags |= VM_RESERVED | VM_IO | VM_MIXEDMAP | VM_DONTEXPAND;
> +    vma->vm_flags |= VM_RESERVED | VM_MIXEDMAP | VM_DONTEXPAND;
> +    if (!((bo->mem.placement & TTM_PL_MASK_MEM) & TTM_PL_FLAG_TT))
> +        vma->vm_flags |= VM_IO;
>        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
>        return 0;
>  out_unref:
>
>