Re: [RFC PATCH] introduce sys_membarrier(): process-wide memory barrier (v5)

Nicholas Miell
2010-01-13T05:00:28Z

On Tue, 2010-01-12 at 20:37 -0500, Mathieu Desnoyers wrote:
> + * sys_membarrier - issue memory barrier on current process running threads
> + * @expedited: (0) Lowest overhead. Few milliseconds latency.
> + * (1) Few microseconds latency.
> + *

Alternate ABI proposal, keeping the possibility of future expansion in
mind:

/*
Mandatory flags to the membarrier system call that the kernel must
understand are in the high 16 bits.
*/
#define MEMBARRIER_MANDATORY_MASK 0xFFFF0000

/*
Optional hints that the kernel can ignore are in the low 16 bits.
*/
#define MEMBARRIER_OPTIONAL_MASK 0x0000FFFF

#define MEMBARRIER_EXPEDITED 1

extern int membarrier(unsigned int flags);

And then add to the system call itself:

if ((flags & MEMBARRIER_MANDATORY_MASK) != 0)
return -EINVAL;

--
Nicholas Miell <nmiell@comcast.net>