[dpdk-dev] [PATCH] mbuf: fix atomic refcnt update synchronization

[Ananyev, Konstantin]

Hi,

> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Linzhe Lee
> Sent: Saturday, September 3, 2016 3:05 AM
> To: Stephen Hemminger <stephen at networkplumber.org>
> Cc: dev at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] mbuf: fix atomic refcnt update synchronization
> 
> yes,stephen.
> 
> my config file here: http://pastebin.com/N0RKGArh
> 
> 2016-09-03 0:51 GMT+08:00 Stephen Hemminger <stephen at networkplumber.org>:
> > On Sat, 3 Sep 2016 00:31:50 +0800
> > Linzhe Lee <slayercat.subscription at gmail.com> wrote:
> >
> >> Thanks for reply, Stephen.
> >>
> >>
> >>
> >> I'm in x86-64, my cpu is `Intel(R) Xeon(R) CPU E5-2620 v3 @ 2.40GHz`.
> >>
> >>
> >>
> >> When allocation mbuf in program1, and transfer it to program2 for
> >> free via ring, the program1 might meet assert in allocate mbuf sometimes.
> >> (`RTE_ASSERT(rte_mbuf_refcnt_read(m) == 0);`)

If you believe there is a problem inside rte_mbuf code,
please provide a test program to reproduce the issue.
So far, I personally don't see any issue in the rte_mbuf code.
Konstantin


> >>
> >>
> >>
> >> but when I using gdb to check it, the refcnt field of mbuf is already
> >> zero. so I believe the problem came from the cache line problem or
> >> incorrect optimization.
> >>
> >>
> >>
> >> When apply this patch, the problem seems solved. I'm submitting it
> >> for your comments.
> >
> > Are you sure you have REFCNT_ATOMIC set?