Paul Jackson <[email protected]> wrote:
>
> From: Paul Jackson <[email protected]>
>
> This patch provides the implementation and cpuset interface for
> an alternative memory allocation policy that can be applied to
> certain kinds of memory allocations, such as the page cache (file
> system buffers) and some slab caches (such as inode caches).
>
> ...
>
> A new per-cpuset file, "memory_spread", is defined. This is
> a boolean flag file, containing a "0" (off) or "1" (on).
> By default it is off, and the kernel allocation placement
> is unchanged. If it is turned on for a given cpuset (write a
> "1" to that cpusets memory_spread file) then the alternative
> policy applies to all tasks in that cpuset.
I'd have thought it would be saner to split these things apart:
"slab_spread", "pagecache_spread", etc.
> +static inline int cpuset_mem_spread_check(void)
> +{
> + return current->flags & PF_MEM_SPREAD;
> +}
That's not a terribly assertive name. cpuset_mem_spread_needed()?
> + if (is_mem_spread(cs))
> + tsk->flags |= PF_MEM_SPREAD;
> + else
> + tsk->flags &= ~PF_MEM_SPREAD;
> task_unlock(tsk);
OT: do we ever set PF_foo on a task other than `current'? I have a feeling
that we do...
> + case FILE_MEM_SPREAD:
> + retval = update_flag(CS_MEM_SPREAD, cs, buffer);
> + atomic_inc(&cpuset_mems_generation);
> + cs->mems_generation = atomic_read(&cpuset_mems_generation);
atomic_inc_return()
> +int cpuset_mem_spread_node(void)
> +{
> + int node;
> +
> + node = next_node(current->cpuset_mem_spread_rotor, current->mems_allowed);
> + if (node == MAX_NUMNODES)
> + node = first_node(current->mems_allowed);
> + current->cpuset_mem_spread_rotor = node;
> + return node;
> +}
hm. What guarantees that a node which is in current->mems_allowed is still
online?
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