linux-kernel - Re: [PATCH v2 7/7] mm/compaction: factor out code to test if we should run compaction for target order

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Date:   Tue, 29 Aug 2023 11:48:59 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     Kemeng Shi <shikemeng@...weicloud.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        mgorman@...hsingularity.net, david@...hat.com, willy@...radead.org
Subject: Re: [PATCH v2 7/7] mm/compaction: factor out code to test if we
 should run compaction for target order



On 8/26/2023 11:36 PM, Kemeng Shi wrote:
> We always do zone_watermark_ok check and compaction_suitable check
> together to test if compaction for target order should be runned.
> Factor these code out to remove repeat code.
> 
> Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
> ---
>   mm/compaction.c | 63 ++++++++++++++++++++++++++++---------------------
>   1 file changed, 36 insertions(+), 27 deletions(-)
> 
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 00b7bba6c72e..6f2b87b026b8 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -2374,6 +2374,30 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
>   	return false;
>   }
>   
> +/*
> + * Should we do compaction for target allocation order.
> + * Return COMPACT_SUCCESS if allocation for target order can be already
> + * satisfied
> + * Return COMPACT_SKIPPED if compaction for target order is likely to fail
> + * Return COMPACT_CONTINUE if compaction for target order should be runned
> + */
> +static inline enum compact_result

I think you should drop the 'inline' to let the compiler make the decision.

> +compaction_suit_allocation_order(struct zone *zone, unsigned int order,
> +				 int highest_zoneidx, unsigned int alloc_flags)

The changes look good to me. So please feel free to add:
Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>

> +{
> +	unsigned long watermark;
> +
> +	watermark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK);
> +	if (zone_watermark_ok(zone, order, watermark, highest_zoneidx,
> +			      alloc_flags))
> +		return COMPACT_SUCCESS;
> +
> +	if (!compaction_suitable(zone, order, highest_zoneidx))
> +		return COMPACT_SKIPPED;
> +
> +	return COMPACT_CONTINUE;
> +}
> +
>   static enum compact_result
>   compact_zone(struct compact_control *cc, struct capture_control *capc)
>   {
> @@ -2399,19 +2423,11 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
>   	cc->migratetype = gfp_migratetype(cc->gfp_mask);
>   
>   	if (!is_via_compact_memory(cc->order)) {
> -		unsigned long watermark;
> -
> -		/* Allocation can already succeed, nothing to do */
> -		watermark = wmark_pages(cc->zone,
> -					cc->alloc_flags & ALLOC_WMARK_MASK);
> -		if (zone_watermark_ok(cc->zone, cc->order, watermark,
> -				      cc->highest_zoneidx, cc->alloc_flags))
> -			return COMPACT_SUCCESS;
> -
> -		/* Compaction is likely to fail */
> -		if (!compaction_suitable(cc->zone, cc->order,
> -					 cc->highest_zoneidx))
> -			return COMPACT_SKIPPED;
> +		ret = compaction_suit_allocation_order(cc->zone, cc->order,
> +						       cc->highest_zoneidx,
> +						       cc->alloc_flags);
> +		if (ret != COMPACT_CONTINUE)
> +			return ret;
>   	}
>   
>   	/*
> @@ -2917,14 +2933,10 @@ static bool kcompactd_node_suitable(pg_data_t *pgdat)
>   		if (!populated_zone(zone))
>   			continue;
>   
> -		/* Allocation can already succeed, check other zones */
> -		if (zone_watermark_ok(zone, pgdat->kcompactd_max_order,
> -				      min_wmark_pages(zone),
> -				      highest_zoneidx, 0))
> -			continue;
> -
> -		if (compaction_suitable(zone, pgdat->kcompactd_max_order,
> -					highest_zoneidx))
> +		if (compaction_suit_allocation_order(zone,
> +				pgdat->kcompactd_max_order,
> +				highest_zoneidx, ALLOC_WMARK_MIN) ==
> +				COMPACT_CONTINUE)
>   			return true;
>   	}
>   
> @@ -2961,12 +2973,9 @@ static void kcompactd_do_work(pg_data_t *pgdat)
>   		if (compaction_deferred(zone, cc.order))
>   			continue;
>   
> -		/* Allocation can already succeed, nothing to do */
> -		if (zone_watermark_ok(zone, cc.order,
> -				      min_wmark_pages(zone), zoneid, 0))
> -			continue;
> -
> -		if (!compaction_suitable(zone, cc.order, zoneid))
> +		if (compaction_suit_allocation_order(zone,
> +				cc.order, zoneid, ALLOC_WMARK_MIN) !=
> +				COMPACT_CONTINUE)
>   			continue;
>   
>   		if (kthread_should_stop())