[Intel-gfx] [PATCH 11/41] drm/i915: Introduce an internal allocator for disposable private objects

[Chris Wilson]

On Fri, Oct 14, 2016 at 01:42:35PM +0100, Tvrtko Ursulin wrote:
> 
> On 14/10/2016 13:18, Chris Wilson wrote:
> >+	gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_RECLAIMABLE;
> >+	if (IS_CRESTLINE(i915) || IS_BROADWATER(i915)) {
> >+		/* 965gm cannot relocate objects above 4GiB. */
> >+		gfp &= ~__GFP_HIGHMEM;
> >+		gfp |= __GFP_DMA32;
> >+	}
> >+
> >+	do {
> >+		int order = min(fls(npages) - 1, max_order);
> 
> I still have reservations on going back to max_order when previous
> chunks required an order decrease. Size of the object is unbound
> since it is indirectly controlled by userspace, correct? How about
> decreasing the max_order on every repeated order decrease, following
> failed order allocation?

> >+		struct page *page;
> >+
> >+		do {
> >+			page = alloc_pages(gfp | (order ? QUIET : 0), order);
> >+			if (page)
> >+				break;
> >+			if (!order--)
> >+				goto err;

Like:
			/* Limit future allocations as well */
			max_order = order;

> >+		} while (1);

We do pass NORETRY | NOWARN for the higher order allocations, so it
shouldn't be as bad it seems?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre