Re: [dpdk-dev] [PATCH v2 1/2] eal: add 128-bit cmpset (x86-64 only)

["Eads, Gage" <gage.eads@intel.com>]

> -----Original Message-----
> From: Gavin Hu (Arm Technology China) [mailto:Gavin.Hu@arm.com]
> Sent: Thursday, January 17, 2019 2:49 AM
> To: Eads, Gage <gage.eads@intel.com>; dev@dpdk.org
> Cc: olivier.matz@6wind.com; arybchenko@solarflare.com; Richardson, Bruce
> <bruce.richardson@intel.com>; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>; Honnappa Nagarahalli
> <Honnappa.Nagarahalli@arm.com>
> Subject: RE: [dpdk-dev] [PATCH v2 1/2] eal: add 128-bit cmpset (x86-64 only)
> 
> 
> 
> > -----Original Message-----
> > From: dev <dev-bounces@dpdk.org> On Behalf Of Gage Eads
> > Sent: Wednesday, January 16, 2019 6:33 AM
> > To: dev@dpdk.org
> > Cc: olivier.matz@6wind.com; arybchenko@solarflare.com;
> > bruce.richardson@intel.com; konstantin.ananyev@intel.com
> > Subject: [dpdk-dev] [PATCH v2 1/2] eal: add 128-bit cmpset (x86-64
> > only)
> >
> > This operation can be used for non-blocking algorithms, such as a
> > non-blocking stack or ring.
> >
> > Signed-off-by: Gage Eads <gage.eads@intel.com>
> > ---
> >  .../common/include/arch/x86/rte_atomic_64.h        | 22
> > ++++++++++++++++++++++
> >  1 file changed, 22 insertions(+)
> >
> > diff --git a/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h
> > b/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h
> > index fd2ec9c53..34c2addf8 100644
> > --- a/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h
> > +++ b/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h
> > @@ -34,6 +34,7 @@
> >  /*
> >   * Inspired from FreeBSD src/sys/amd64/include/atomic.h
> >   * Copyright (c) 1998 Doug Rabson
> > + * Copyright (c) 2019 Intel Corporation
> >   * All rights reserved.
> >   */
> >
> > @@ -208,4 +209,25 @@ static inline void
> > rte_atomic64_clear(rte_atomic64_t *v)  }  #endif
> >
> > +static inline int
> > +rte_atomic128_cmpset(volatile uint64_t *dst, uint64_t *exp, uint64_t
> > *src)
> > +{
> > +uint8_t res;
> > +
> > +asm volatile (
> > +      MPLOCKED
> > +      "cmpxchg16b %[dst];"
> > +      " sete %[res]"
> > +      : [dst] "=m" (*dst),
> > +[res] "=r" (res)
> > +      : "c" (src[1]),
> > +"b" (src[0]),
> > +"m" (*dst),
> > +"d" (exp[1]),
> > +"a" (exp[0])
> > +      : "memory");
> > +
> > +return res;
> > +}
> > +
> 
> CONFIG_RTE_DRIVER_MEMPOOL_NB_STACK=y can't coexist with
> RTE_FORCE_INTRINSICS=y, this should be explicitly described somewhere in the
> configuration and documentations.
> 

This patch places rte_atomic128_cmpset() outside of the RTE_FORCE_INTRINSICS ifndef, and this file is included regardless of that config flag, so it's compiled either way.

> >  #endif /* _RTE_ATOMIC_X86_64_H_ */
> > --
> > 2.13.6
> 
> IMPORTANT NOTICE: The contents of this email and any attachments are
> confidential and may also be privileged. If you are not the intended recipient,
> please notify the sender immediately and do not disclose the contents to any
> other person, use it for any purpose, or store or copy the information in any
> medium. Thank you.