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drm/vmwgfx: Use VM_PFNMAP instead of VM_MIXEDMAP when possible

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For shared, and read-only private mappings of graphics memory, use
VM_PFNMAP instead of VM_MIXEDMAP. This means less accounting overhead
when inserting and removing page-table entries. TTM doesn't do this
by default, since there was a performance problem with book-keeping of
write-combined mappings. Since vmwgfx solely uses cached mappings, that's
not a problem and now that the TTM vm has largely been turned into
helpers, we can use VM_PFNMAP on a per-driver basis

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
This commit is contained in:
Thomas Hellstrom 2019-12-04 11:42:15 +01:00
parent 61780dd7a4
commit b204142520
1 changed files with 4 additions and 0 deletions
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4
drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
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@ -45,6 +45,10 @@ int vmw_mmap(struct file *filp, struct vm_area_struct *vma)
vma->vm_ops = &vmw_vm_ops;
/* Use VM_PFNMAP rather than VM_MIXEDMAP if not a COW mapping */
if ((vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) != VM_MAYWRITE)
vma->vm_flags = (vma->vm_flags & ~VM_MIXEDMAP) | VM_PFNMAP;
return 0;
}