Re: [RFC][PATCH 2/6] CART Implementation

I'm being dense again. I really should not write these mails at 6am :-{

On Mon, 2005-08-29 at 06:15 +0200, Peter Zijlstra wrote:

On Sun, 2005-08-28 at 23:02 -0400, Rik van Riel wrote:

quoted

On Sat, 27 Aug 2005, a.p.zijlstra@chello.nl wrote:

quoted

+static void bucket_stats(struct nr_bucket * nr_bucket, int * b1, int * b2)
+{
+	unsigned int i, b[2] = {0, 0};
+	for (i = 0; i < 2; ++i) {
+		unsigned int j = nr_bucket->hand[i];
+		do
+		{
+			u32 *slot = &nr_bucket->slot[j];
+			if (!!(GET_FLAGS(*slot) & NR_list) != !!i)
+				break;
+
+			j = GET_INDEX(*slot);
+			++b[i];
+		} while (j != nr_bucket->hand[i]);

Does this properly skip empty slots ?

I should idd skip 0 cookie slots for the stats. The hidden assumption
was that the balance would not be disturbed by these null cookies; which
is not obvious true. Thanks for the hint.

There are no empty slots. This thing always has B1_j + B2_j = NR_SLOTS.
I couldn't manage keeping track of two lists and empty slots. It doesn't
really matter though. I just have to start out with |B1| = 0 and |B2| =
c. I fill B2_j with zero cookies, so getting a hit there is very
unlikely, that way they just get overwritten due to old age and all is
well.

I could ofcourse make the head 1 byte and have 4 list heads in there,
that way I even have 1 spare. I'll see what kind of mess that would
give ;-).

quoted

Remember that a page that got paged in leaves a zeroed
out slot in the bucket...

Yeah, I was playing aroung with that. I'll change that back because it
does indeed generate a problem elsewhere.

should be there again in the second series I send out earlier.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>