> -----Original Message----- > From: Alexander Duyck [mailto:alexander.duyck@xxxxxxxxx] > Sent: Wednesday, December 10, 2014 9:29 PM > To: Alexander Duyck; linux-arch@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; arnd@xxxxxxxx; davem@xxxxxxxxxxxxx > Cc: mathieu.desnoyers@xxxxxxxxxx; peterz@xxxxxxxxxxxxx; > benh@xxxxxxxxxxxxxxxxxxx; heiko.carstens@xxxxxxxxxx; mingo@xxxxxxxxxx; > mikey@xxxxxxxxxxx; linux@xxxxxxxxxxxxxxxx; Skidmore, Donald C; Vick, > Matthew; geert@xxxxxxxxxxxxxx; Kirsher, Jeffrey T; romieu@xxxxxxxxxxxxx; > paulmck@xxxxxxxxxxxxxxxxxx; nic_swsd@xxxxxxxxxxx; > will.deacon@xxxxxxx; michael@xxxxxxxxxxxxxx; Luck, Tony; torvalds@linux- > foundation.org; oleg@xxxxxxxxxx; schwidefsky@xxxxxxxxxx; > fweisbec@xxxxxxxxx > Subject: Re: [PATCH v7 0/4] arch: Add lightweight memory barriers for > coherent memory access > > On 11/25/2014 12:35 PM, Alexander Duyck wrote: > > These patches introduce two new primitives for synchronizing cache > > coherent memory writes and reads. These two new primitives are: > > > > dma_rmb() > > dma_wmb() > > > > The first patch cleans up some unnecessary overhead related to the > > definition of read_barrier_depends, smp_read_barrier_depends, and > > comments related to the barrier. > > > > The second patch adds the primitives for the applicable architectures > > and asm-generic. > > > > The third patch adds the barriers to r8169 which turns out to be a > > good example of where the new barriers might be useful as they have > > full > > rmb()/wmb() barriers ordering accesses to the descriptors and the > > DescOwn bit. > > > > The fourth patch adds support for coherent_rmb() to the Intel fm10k, > > igb, and ixgbe drivers. Testing with the ixgbe driver has shown a > > processing time reduction of at least 7ns per 64B frame on a Core i7-4930K. > > > > This patch series is essentially the v7 for: > > v4-6: Add lightweight memory barriers for coherent memory access > > v3: Add lightweight memory barriers fast_rmb() and fast_wmb() > > v2: Introduce load_acquire() and store_release() > > v1: Introduce read_acquire() > > > > The key changes in this patch series versus the earlier patches are: > > v7: > > - Dropped test/debug patch that was accidentally slipped in > > v6: > > - Replaced "memory based device I/O" with "consistent memory" in > > docs > > - Added reference to DMA-API.txt to explain consistent memory > > v5: > > - Renamed barriers dma_rmb and dma_wmb > > - Undid smp_wmb changes in x86 and PowerPC > > - Defined smp_rmb as __lwsync for SMP case on PowerPC > > v4: > > - Renamed barriers coherent_rmb and coherent_wmb > > - Added smp_lwsync for use in > smp_load_acquire/smp_store_release > > v3: > > - Moved away from acquire()/store() and instead focused on barriers > > - Added cleanup of read_barrier_depends > > - Added change in r8169 to fix cur_tx/DescOwn ordering > > - Simplified changes to just replacing/moving barriers in r8169 > > - Added update to documentation with code example > > v2: > > - Renamed read_acquire() to be consistent with smp_load_acquire() > > - Changed barrier used to be consistent with smp_load_acquire() > > - Updated PowerPC code to use __lwsync based on IBM article > > - Added store_release() as this is a viable use case for drivers > > - Added r8169 patch which is able to fully use primitives > > - Added fm10k/igb/ixgbe patch which is able to test performance > > > > --- > > > > Alexander Duyck (4): > > arch: Cleanup read_barrier_depends() and comments > > arch: Add lightweight memory barriers dma_rmb() and dma_wmb() > > r8169: Use dma_rmb() and dma_wmb() for DescOwn checks > > fm10k/igb/ixgbe: Use dma_rmb on Rx descriptor reads > > > > > > Documentation/memory-barriers.txt | 42 +++++++++++++++ > > arch/alpha/include/asm/barrier.h | 51 ++++++++++++++++++ > > arch/arm/include/asm/barrier.h | 4 + > > arch/arm64/include/asm/barrier.h | 3 + > > arch/blackfin/include/asm/barrier.h | 51 ++++++++++++++++++ > > arch/ia64/include/asm/barrier.h | 25 ++++----- > > arch/metag/include/asm/barrier.h | 19 ++++--- > > arch/mips/include/asm/barrier.h | 61 ++-------------------- > > arch/powerpc/include/asm/barrier.h | 19 ++++--- > > arch/s390/include/asm/barrier.h | 7 ++- > > arch/sparc/include/asm/barrier_64.h | 7 ++- > > arch/x86/include/asm/barrier.h | 70 ++++--------------------- > > arch/x86/um/asm/barrier.h | 20 ++++--- > > drivers/net/ethernet/intel/fm10k/fm10k_main.c | 6 +- > > drivers/net/ethernet/intel/igb/igb_main.c | 6 +- > > drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 9 +-- > > drivers/net/ethernet/realtek/r8169.c | 29 ++++++++-- > > include/asm-generic/barrier.h | 8 +++ > > 18 files changed, 258 insertions(+), 179 deletions(-) > > > > -- > > It occurs to me that I never got a sign off from any of the maintainers on > getting this pulled in. > > Since the merge window is open I was wondering which tree I should make > sure these patches apply to and who will be the one to pull them in? > Since I was modifying network drivers should I resubmit them for netdev, or > should I submit them for asm-generic or some other tree? > > - Alex For at least ixgbe, it looks good to me. 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