Re: [net-next v2 02/15] i40evf: correctly program RSS HLUT table

Re: [net-next v2 02/15] i40evf: correctly program RSS HLUT table

[Or Gerlitz]

On Wed, Mar 19, 2014 at 5:42 AM, Jeff Kirsher
<jeffrey.t.kirsher@intel.com> wrote:
> From: Mitch Williams <mitch.a.williams@intel.com>
>
> The HLUT programming loop in in i40evf_configure_rss was a) overly-
> complicated, and b) just plain broken. Most of the entries ended up being
> not written at all, so most of the flows ended up at queue zero.

In the V2 cover letter you wrote

dropped patch Mitch's patch "i40evf: correctly program RSS HLUT table"

so what is this patch?

Re: [net-next v2 02/15] i40evf: correctly program RSS HLUT table

[Jeff Kirsher]

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On Wed, 2014-03-19 at 10:08 +0200, Or Gerlitz wrote:
> On Wed, Mar 19, 2014 at 5:42 AM, Jeff Kirsher
> <jeffrey.t.kirsher@intel.com> wrote:
> > From: Mitch Williams <mitch.a.williams@intel.com>
> >
> > The HLUT programming loop in in i40evf_configure_rss was a) overly-
> > complicated, and b) just plain broken. Most of the entries ended up being
> > not written at all, so most of the flows ended up at queue zero.
> 
> In the V2 cover letter you wrote
> 
> dropped patch Mitch's patch "i40evf: correctly program RSS HLUT table"
> 
> so what is this patch?

Sorry, that was may bad.  In v2 I dropped patch 3 which was "i40evf:
Support RSS option in ethtool" patch.  I referenced the wrong patch in
the cover letter, thanks for noticing that Or.

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Re: [net-next v2 02/15] i40evf: correctly program RSS HLUT table

[David Miller]

From: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Date: Tue, 18 Mar 2014 20:42:00 -0700

> +#define NEXT_QUEUE(_j) (++_j >= adapter->vsi_res->num_queue_pairs ? _j = 0 : _j)

I would strong recommend breaking the increment out of the test
and using a function rather than a macro:

static int next_queue(struct i40evf_adapter *adapter, int j)
{
	j += 1;

	return j >= adapter->vsi_res->num_queue_pairs ? 0 : j;
}

 ..

	j = next_queue(adapter, j);

[net-next v2 02/15] i40evf: correctly program RSS HLUT table

[Jeff Kirsher]

From: Mitch Williams <mitch.a.williams@intel.com>

The HLUT programming loop in in i40evf_configure_rss was a) overly-
complicated, and b) just plain broken. Most of the entries ended up being
not written at all, so most of the flows ended up at queue zero.

Refactor the HLUT programming loop to simply walk through the registers
and write four values to each one, incrementing through the number of
available queues.

Change-ID: I75766179bc67e4e997187794f3144e28c83fd00d
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Catherine Sullivan <catherine.sullivan@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---
 drivers/net/ethernet/intel/i40evf/i40evf_main.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40evf/i40evf_main.c b/drivers/net/ethernet/intel/i40evf/i40evf_main.c
index d62e27f..7cb0cda 100644
--- a/drivers/net/ethernet/intel/i40evf/i40evf_main.c
+++ b/drivers/net/ethernet/intel/i40evf/i40evf_main.c
@@ -1414,6 +1414,7 @@ restart_watchdog:
 	schedule_work(&adapter->adminq_task);
 }
 
+#define NEXT_QUEUE(_j) (++_j >= adapter->vsi_res->num_queue_pairs ? _j = 0 : _j)
 /**
  * i40evf_configure_rss - Prepare for RSS if used
  * @adapter: board private structure
@@ -1444,15 +1445,13 @@ static void i40evf_configure_rss(struct i40evf_adapter *adapter)
 	wr32(hw, I40E_VFQF_HENA(1), (u32)(hena >> 32));
 
 	/* Populate the LUT with max no. of queues in round robin fashion */
-	for (i = 0, j = 0; i < I40E_VFQF_HLUT_MAX_INDEX; i++, j++) {
-		if (j == adapter->vsi_res->num_queue_pairs)
-			j = 0;
-		/* lut = 4-byte sliding window of 4 lut entries */
-		lut = (lut << 8) | (j &
-			 ((0x1 << 8) - 1));
-		/* On i = 3, we have 4 entries in lut; write to the register */
-		if ((i & 3) == 3)
-			wr32(hw, I40E_VFQF_HLUT(i >> 2), lut);
+	j = adapter->vsi_res->num_queue_pairs;
+	for (i = 0; i <= I40E_VFQF_HLUT_MAX_INDEX; i++) {
+		lut = NEXT_QUEUE(j);
+		lut |= NEXT_QUEUE(j) << 8;
+		lut |= NEXT_QUEUE(j) << 16;
+		lut |= NEXT_QUEUE(j) << 24;
+		wr32(hw, I40E_VFQF_HLUT(i), lut);
 	}
 	i40e_flush(hw);
 }
-- 
1.8.3.1