> -----Original Message----- > From: David Marchand <[email protected]> > Sent: Monday, September 28, 2020 5:23 AM > To: Steven Lariau <[email protected]>; Eads, Gage <[email protected]> > Cc: Olivier Matz <[email protected]>; dev <[email protected]>; nd > <[email protected]> > Subject: Re: [dpdk-dev] [PATCH v2 1/5] lib/stack: fix inconsistent weak / > strong > cas > > On Fri, Sep 25, 2020 at 7:44 PM Steven Lariau <[email protected]> wrote: > > > > Fix cmpexchange usage of weak / strong. > > The generated code is the same on x86 and ARM (there is no weak > > cmpexchange), but the old usage was inconsistent. > > For push and pop update size, weak is used because cmpexchange is inside > > a loop. > > For pop update root, strong is used even though cmpexchange is inside a > > loop, because there may be a lot of operations to do in a loop iteration > > (locate the new head). > > Is this patch backport material?
It's not a bugfix. It could help performance on a system with weak cmpexchange -- e.g. the pop-update change would ensure no spurious failures (which the code can handle, but would require another relatively expensive pass through the pop loop.) Thanks, Gage
