Re: [PATCH 3/3] fm10k/igb/ixgbe: Use load_acquire on Rx descriptor

On Thu, 2014-11-13 at 11:27 -0800, Alexander Duyck wrote:

This change makes it so that load_acquire is used when reading the Rx
descriptor.  The advantage of load_acquire is that it allows for a
much
lower cost barrier on x86, ia64, powerpc, arm64, and s390
architectures
than a traditional memory barrier when dealing with reads that only
have
to synchronize to system memory.

In addition I have updated the code so that it just checks to see if
any
bits have been set instead of just the DD bit since the DD bit will
always
be set as a part of a descriptor write-back so we just need to check
for a
non-zero value being present at that memory location rather than just
checking for any specific bit.  This allows the code itself to appear
much
cleaner and allows the compiler more room to optimize.

Cc: Jeff Kirsher <redacted>
Cc: Matthew Vick <redacted>
Cc: Don Skidmore <redacted>
Signed-off-by: Alexander Duyck <redacted>
---
 drivers/net/ethernet/intel/fm10k/fm10k_main.c |    8 +++-----
 drivers/net/ethernet/intel/igb/igb_main.c     |    8 +++-----
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |   11 ++++-------
 3 files changed, 10 insertions(+), 17 deletions(-)

Based on the discussion on patch 01 of the series, it appears changes
are coming to the series, so I won't be picking up this patch.  I will
wait for Alex to re-spin the series with the suggested changes.