From: Bruce Richardson <bruce.richardson@intel.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: dev@dpdk.org, ibetts <ian.betts@intel.com>
Subject: Re: [dpdk-dev] [PATCH v5 2/4] examples: add lthread subsystem for performance-thread
Date: Thu, 3 Dec 2015 16:46:27 +0000 [thread overview]
Message-ID: <20151203164626.GA13272@bricha3-MOBL3> (raw)
In-Reply-To: <20151203083139.32b82334@xeon-e3>
On Thu, Dec 03, 2015 at 08:31:39AM -0800, Stephen Hemminger wrote:
> On Thu, 3 Dec 2015 09:28:23 +0000
> ibetts <ian.betts@intel.com> wrote:
>
> > +/*
> > + * Atomically set a value and return the old value
> > + */
> > +static inline uint64_t
> > +atomic64_xchg(uint64_t *ptr, uint64_t val) __attribute__ ((always_inline));
> > +static inline uint64_t
> > +atomic64_xchg(uint64_t *ptr, uint64_t val)
>
> You don't need a forward declaration for this.
> Instead do:
>
> static inline uint64_t __attribute__((always_inline))
> atomic_xchg64(uint64_t *ptr, uint64_t val)
>
> Really should be in rte_atomic.h as a primitive
> and the assembly macro is missing change to ptr so Gcc might optmize it away.
>
> Something like this mayb?
>
> static inline uint64_t __attribute__ ((always_inline));
> rte_atomic64_xchg(uint64_t *ptr, uint64_t val)
> {
> asm volatile (
> MPLOCKED
> "xchgq %[ptr],%[val];"
> : [val] "=r" (val)
> [ptr] "=m" (*ptr)
> : [ptr] "m" (*ptr),
> "a" (val)
> : "memory");
>
> return val;
> }
Rather than using assembly, I believe the gcc builtin __sync_lock_test_and_set
is actually an xchg op, so can be used here.
/Bruce
next prev parent reply other threads:[~2015-12-03 16:46 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-03 9:28 [dpdk-dev] [PATCH v5 0/4] examples: add performance-thread ibetts
2015-12-03 9:28 ` [dpdk-dev] [PATCH v5 1/4] doc: add sample application guide for performance-thread ibetts
2015-12-03 9:28 ` [dpdk-dev] [PATCH v5 2/4] examples: add lthread subsystem " ibetts
2015-12-03 16:31 ` Stephen Hemminger
2015-12-03 16:46 ` Bruce Richardson [this message]
2015-12-03 17:15 ` Betts, Ian
2015-12-03 9:28 ` [dpdk-dev] [PATCH v5 3/4] examples: add l3fwd-thread example in performance-thread ibetts
2015-12-03 16:32 ` Stephen Hemminger
2015-12-03 17:18 ` Betts, Ian
2015-12-03 9:28 ` [dpdk-dev] [PATCH v5 4/4] examples: add pthread_shim example to performance thread ibetts
2015-12-03 9:48 ` [dpdk-dev] [PATCH v5 0/4] examples: add performance-thread Kulasek, TomaszX
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