On Wed, 21 Sep 2016, zijun_hu wrote:
> From: zijun_hu <zijun_hu@xxxxxxx>
>
> correct lazy_max_pages() return value if the number of online
> CPUs is power of 2
>
> Signed-off-by: zijun_hu <zijun_hu@xxxxxxx>
> ---
> mm/vmalloc.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index a125ae8..2804224 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -594,7 +594,9 @@ static unsigned long lazy_max_pages(void)
> {
> unsigned int log;
>
> - log = fls(num_online_cpus());
> + log = num_online_cpus();
> + if (log > 1)
> + log = (unsigned int)get_count_order(log);
>
> return log * (32UL * 1024 * 1024 / PAGE_SIZE);
> }
The implementation of lazy_max_pages() is somewhat arbitrarily defined,
the existing approximation has been around for eight years and
num_online_cpus() isn't intended to be rounded up to the next power of 2.
I'd be inclined to just leave it as it is.
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