[PATCH] mm/damon/core: skip apply schemes if empty

[PATCH] mm/damon/core: skip apply schemes if empty

[Huaisheng Ye]

Sometimes there is no scheme in damon's context, for example
just use damo record to monitor workload's data access pattern.

If current damon context doesn't have any scheme in the list,
kdamond has no need to iterate over list of all targets and regions
but do nothing.

So, skip apply schemes when ctx->schemes is empty.

Signed-off-by: Huaisheng Ye <huaisheng.ye@intel.com>
---
 mm/damon/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index ceec75b88ef9..f338691e4591 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1230,7 +1230,8 @@ static int kdamond_fn(void *data)
 			if (ctx->callback.after_aggregation &&
 					ctx->callback.after_aggregation(ctx))
 				break;
-			kdamond_apply_schemes(ctx);
+			if (!list_empty(&ctx->schemes))
+				kdamond_apply_schemes(ctx);
 			kdamond_reset_aggregated(ctx);
 			kdamond_split_regions(ctx);
 			if (ctx->ops.reset_aggregated)
-- 
2.31.1

Re: [PATCH] mm/damon/core: skip apply schemes if empty

[SeongJae Park]

Hi Huaisheng,

On Mon, 16 Jan 2023 14:23:47 +0800 Huaisheng Ye <huaisheng.ye@intel.com> wrote:

> Sometimes there is no scheme in damon's context, for example
> just use damo record to monitor workload's data access pattern.
> 
> If current damon context doesn't have any scheme in the list,
> kdamond has no need to iterate over list of all targets and regions
> but do nothing.
> 
> So, skip apply schemes when ctx->schemes is empty.

Good finding, thanks!

> 
> Signed-off-by: Huaisheng Ye <huaisheng.ye@intel.com>

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

> ---
>  mm/damon/core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/damon/core.c b/mm/damon/core.c
> index ceec75b88ef9..f338691e4591 100644
> --- a/mm/damon/core.c
> +++ b/mm/damon/core.c
> @@ -1230,7 +1230,8 @@ static int kdamond_fn(void *data)
>  			if (ctx->callback.after_aggregation &&
>  					ctx->callback.after_aggregation(ctx))
>  				break;
> -			kdamond_apply_schemes(ctx);
> +			if (!list_empty(&ctx->schemes))
> +				kdamond_apply_schemes(ctx);
>  			kdamond_reset_aggregated(ctx);
>  			kdamond_split_regions(ctx);
>  			if (ctx->ops.reset_aggregated)
> -- 
> 2.31.1
> 
>