Re: [rfc patch 2/6] vmscan: make distinction between memcg reclaim and LRU list selection

[Rik van Riel <riel@redhat.com>]

On 05/12/2011 10:53 AM, Johannes Weiner wrote:
> The reclaim code has a single predicate for whether it currently
> reclaims on behalf of a memory cgroup, as well as whether it is
> reclaiming from the global LRU list or a memory cgroup LRU list.
>
> Up to now, both cases always coincide, but subsequent patches will
> change things such that global reclaim will scan memory cgroup lists.
>
> This patch adds a new predicate that tells global reclaim from memory
> cgroup reclaim, and then changes all callsites that are actually about
> global reclaim heuristics rather than strict LRU list selection.
>
> Signed-off-by: Johannes Weiner<hannes@cmpxchg.org>
> ---
>   mm/vmscan.c |   96 ++++++++++++++++++++++++++++++++++------------------------
>   1 files changed, 56 insertions(+), 40 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index f6b435c..ceeb2a5 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -104,8 +104,12 @@ struct scan_control {
>   	 */
>   	reclaim_mode_t reclaim_mode;
>
> -	/* Which cgroup do we reclaim from */
> -	struct mem_cgroup *mem_cgroup;
> +	/*
> +	 * The memory cgroup we reclaim on behalf of, and the one we
> +	 * are currently reclaiming from.
> +	 */
> +	struct mem_cgroup *memcg;
> +	struct mem_cgroup *current_memcg;

I can't say I'm fond of these names.  I had to read the
rest of the patch to figure out that the old mem_cgroup
got renamed to current_memcg.

Would it be better to call them my_memcg and reclaim_memcg?

Maybe somebody else has better suggestions...

Other than the naming, no objection.