Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751200AbaKYUgV (ORCPT ); Tue, 25 Nov 2014 15:36:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35474 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750812AbaKYUgT (ORCPT ); Tue, 25 Nov 2014 15:36:19 -0500 Subject: [PATCH v7 0/4] arch: Add lightweight memory barriers for coherent memory access From: Alexander Duyck To: linux-arch@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: mathieu.desnoyers@polymtl.ca, peterz@infradead.org, benh@kernel.crashing.org, heiko.carstens@de.ibm.com, mingo@kernel.org, mikey@neuling.org, linux@arm.linux.org.uk, donald.c.skidmore@intel.com, matthew.vick@intel.com, geert@linux-m68k.org, jeffrey.t.kirsher@intel.com, romieu@fr.zoreil.com, paulmck@linux.vnet.ibm.com, nic_swsd@realtek.com, arnd@arndb.de, will.deacon@arm.com, michael@ellerman.id.au, tony.luck@intel.com, torvalds@linux-foundation.org, oleg@redhat.com, schwidefsky@de.ibm.com, fweisbec@gmail.com, davem@davemloft.net Date: Tue, 25 Nov 2014 12:35:06 -0800 Message-ID: <20141125203310.8240.27370.stgit@ahduyck-server> User-Agent: StGit/0.17-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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(-) -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/