Ben, ovs-atomic-msvc.h contains support for 8,16,32 and 64-bit arithmetic and logical operations. Regarding 64-bit operations, like read and write, they are performed using specific 64-bit interlocked functions, i.e. InterlockedCompareExchange64 and, respectivelly, InterlockedOr64. Both functions are performed atomically.
All remaining 64-bit operations use, also, 64-bit interlocked functions, which are executed atomically, except for logical AND operation. For the latter operation, an intrinsic function is used, _InterlockedExchangeAdd64, which means that is a faster function built in to the compiler. More details about this is here: https://msdn.microsoft.com/ro-ro/library/26td21ds(v=vs.80).aspx. -----Original Message----- From: Ben Pfaff [mailto:b...@ovn.org] Sent: Tuesday, 29 March, 2016 00:25 To: Sorin Vinturis Cc: Guru Shetty; dev@openvswitch.org Subject: Re: [ovs-dev] [PATCH] datapath-windows: Add Windows thread atomic APIs for x64 binaries. On Mon, Mar 28, 2016 at 09:11:24PM +0000, Sorin Vinturis wrote: > Hi Guru, > > I have verified the ovs-atomic-msvc.h header and all the defined > macros and functions have 32-bit and 64-bit correspondent. All 64-bit > macros use InterlockedXXX functions that are atomic: > InterlockedExchangeNoFence64, InterlockedExchange64, > InterlockedCompareExchange64, _InterlockedExchangeAdd64, > InterlockedAnd64, InterlockedOr64, InterlockedXor64. I have ran > test-atomic.c unit tests, on both 32-bit and 64-bit platforms, and all > the tests are verified. > > I also tested the 64-bit build on Hyper-V and it is stable. > > Is there a reason why we should not use ovs-atomic-msvc APIs for 64-bit > builds? ovs-atomic-msvc.h seems pretty oriented toward a 32-bit build. At least, I really doubt MSVC would break 64-bit reads and writes into two 32-bit reads and writes on 64-bit builds, which is what the code in the header currently assumes. You don't want to update it to handle 64-bit builds differently? I guess that these would be optimizations, but they seem straightforward. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
