Re: [PATCH] x86_64: Auto size the per cpu area.

Eric W. Biederman
2006-08-08T06:31:47Z

Andrew Morton <akpm@osdl.org> writes:

> On Mon, 07 Aug 2006 23:47:23 -0600
> ebiederm@xmission.com (Eric W. Biederman) wrote:
>
>> +#ifdef CONFIG_MODULES
>> +# define PERCPU_MODULE_RESERVE 8192
>> +#else
>> +# define PERCPU_MODULE_RESERVE 0
>> +#endif
>> +
>> +#define PERCPU_ENOUGH_ROOM \
>> + (ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES) + \
>> + PERCPU_MODULE_RESERVE)
>> +
>
> Seems sane, but isn't 8192 a bit small?

By my measure 8K is about 1/2KB less than what we have free in
2.6.18-rc3. So it looks like a good initial guess to me.

Eric