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

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Message-Id: <20230116173159.23307-1-sj@kernel.org>
Date:   Mon, 16 Jan 2023 17:31:59 +0000
From:   SeongJae Park <sj@...nel.org>
To:     Huaisheng Ye <huaisheng.ye@...el.com>
Cc:     sj@...nel.org, akpm@...ux-foundation.org, damon@...ts.linux.dev,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/damon/core: skip apply schemes if empty

Hi Huaisheng,

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

Reviewed-by: SeongJae Park <sj@...nel.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
> 
>