[dpdk-dev] memory barriers in rte_ring

2014-03-27 Thread Venkatesan, Venky
Hemminger Sent: Thursday, March 27, 2014 1:20 PM To: Olivier MATZ Cc: dev at dpdk.org Subject: Re: [dpdk-dev] memory barriers in rte_ring On Thu, 27 Mar 2014 20:47:37 +0100 Olivier MATZ wrote: > Hi Stephen, > > On 03/27/2014 08:06 PM, Stephen Hemminger wrote: > > Long answer: for the mul

[dpdk-dev] memory barriers in rte_ring

2014-03-27 Thread Olivier MATZ
Hi Stephen, On 03/27/2014 08:06 PM, Stephen Hemminger wrote: > Long answer: for the multple CPU access ring, it is equivalent to smp_wmb and > smp_rmb > in Linux kernel. For x86 where DPDK is used, this can normally be replaced > by simpler > compiler barrier. In kernel there is a special fl

[dpdk-dev] memory barriers in rte_ring

2014-03-27 Thread Olivier MATZ
Hi, The commit 286bd05bf7 [1] removed the memory barriers in the ring functions. This patch is present in DPDK since version 1.4.0r0, so I guess it does not cause any issue. But after checking the excellent Linux kernel documentation about memory barriers [2], I'm wondering why memory barriers wo

[dpdk-dev] memory barriers in rte_ring

2014-03-27 Thread Stephen Hemminger
On Thu, 27 Mar 2014 20:47:37 +0100 Olivier MATZ wrote: > Hi Stephen, > > On 03/27/2014 08:06 PM, Stephen Hemminger wrote: > > Long answer: for the multple CPU access ring, it is equivalent to smp_wmb > > and smp_rmb > > in Linux kernel. For x86 where DPDK is used, this can normally be > > re

[dpdk-dev] memory barriers in rte_ring

2014-03-27 Thread Stephen Hemminger
On Thu, 27 Mar 2014 17:48:21 +0100 Olivier MATZ wrote: > Hi, > > The commit 286bd05bf7 [1] removed the memory barriers in the ring > functions. This patch is present in DPDK since version 1.4.0r0, so I > guess it does not cause any issue. > > But after checking the excellent Linux kernel docume