From: Alexander Duyck <alexander.h.duyck@redhat.com>
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, 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
Subject: [PATCH v5 0/4] arch: Add lightweight memory barriers for coherent memory access
Date: Tue, 18 Nov 2014 17:23:28 -0800 [thread overview]
Message-ID: <20141119012205.9563.95544.stgit@ahduyck-server> (raw)
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 v4 for:
v4: 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:
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 | 41 +++++++++++++++
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, 257 insertions(+), 179 deletions(-)
--
next reply other threads:[~2014-11-19 1:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-19 1:23 Alexander Duyck [this message]
2014-11-19 1:23 ` [PATCH v5 1/4] arch: Cleanup read_barrier_depends() and comments Alexander Duyck
2014-11-19 1:24 ` [PATCH v5 2/4] arch: Add lightweight memory barriers dma_rmb() and dma_wmb() Alexander Duyck
2014-11-25 14:01 ` Will Deacon
2014-11-25 16:26 ` Alexander Duyck
2014-11-26 16:04 ` Will Deacon
2014-11-25 23:15 ` Benjamin Herrenschmidt
2014-11-19 1:24 ` [PATCH v5 3/4] r8169: Use dma_rmb() and dma_wmb() for DescOwn checks Alexander Duyck
2014-11-19 1:24 ` [PATCH v5 4/4] fm10k/igb/ixgbe: Use dma_rmb on Rx descriptor reads Alexander Duyck
2014-11-19 1:28 ` Jeff Kirsher
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