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

[Nicholas Miell]

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@xxxxxxxxxxx>

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