On Fri, 2018-03-23 at 14:53 -0700, Alexander Duyck wrote: > On Fri, Mar 23, 2018 at 11:52 AM, Sinan Kaya <okaya@xxxxxxxxxxxxxx> > wrote: > > Code includes wmb() followed by writel() in multiple places. writel() > > already has a barrier on some architectures like arm64. > > > > This ends up CPU observing two barriers back to back before executing > > the > > register write. > > > > Since code already has an explicit barrier call, changing writel() to > > writel_relaxed(). > > > > I did a regex search for wmb() followed by writel() in each drivers > > directory. > > I scrubbed the ones I care about in this series. > > > > I considered "ease of change", "popular usage" and "performance > > critical > > path" as the determining criteria for my filtering. > > > > We used relaxed API heavily on ARM for a long time but > > it did not exist on other architectures. For this reason, relaxed > > architectures have been paying double penalty in order to use the > > common > > drivers. > > > > Now that relaxed API is present on all architectures, we can go and > > scrub > > all drivers to see what needs to change and what can remain. > > > > We start with mostly used ones and hope to increase the coverage over > > time. > > It will take a while to cover all drivers. > > > > Feel free to apply patches individually. > > I looked over the set and they seem good. > > Reviewed-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx> Grrr, patch 1 does not apply cleanly to my next-queue tree (dev-queue branch). I will deal with this series in a day or two, after I have dealt with my driver pull requests. > > > > Changes since v6: > > clean up between 2..6 and then make your Alex's changes on 1 and 7 > > The mmiowb shouldn't be needed for Rx. Only one CPU will be running > > NAPI for the queue and we will synchronize this with a full writel > > anyway when we re-enable the interrupts. > > > > Sinan Kaya (7): > > i40e/i40evf: Eliminate duplicate barriers on weakly-ordered archs > > ixgbe: eliminate duplicate barriers on weakly-ordered archs > > igbvf: eliminate duplicate barriers on weakly-ordered archs > > igb: eliminate duplicate barriers on weakly-ordered archs > > fm10k: Eliminate duplicate barriers on weakly-ordered archs > > ixgbevf: keep writel() closer to wmb() > > ixgbevf: eliminate duplicate barriers on weakly-ordered archs > > > > drivers/net/ethernet/intel/fm10k/fm10k_main.c | 4 ++-- > > drivers/net/ethernet/intel/i40e/i40e_txrx.c | 14 ++++++++++---- > > drivers/net/ethernet/intel/i40evf/i40e_txrx.c | 4 ++-- > > drivers/net/ethernet/intel/igb/igb_main.c | 4 ++-- > > drivers/net/ethernet/intel/igbvf/netdev.c | 4 ++-- > > drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 8 ++++---- > > drivers/net/ethernet/intel/ixgbevf/ixgbevf.h | 5 ----- > > drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c | 11 ++++++++--- > > 8 files changed, 30 insertions(+), 24 deletions(-) > > > > -- > > 2.7.4 > >
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