linux-kernel - Re: [RFC PATCH 14/26] mm: compaction: simplify should_compact

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Message-ID: <20230421143654.g6ta3kd6ea7fsmp6@techsingularity.net>
Date:   Fri, 21 Apr 2023 15:36:54 +0100
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Johannes Weiner <hannes@...xchg.org>
Cc:     linux-mm@...ck.org, Kaiyang Zhao <kaiyang2@...cmu.edu>,
        Vlastimil Babka <vbabka@...e.cz>,
        David Rientjes <rientjes@...gle.com>,
        linux-kernel@...r.kernel.org, kernel-team@...com
Subject: Re: [RFC PATCH 14/26] mm: compaction: simplify should_compact_retry()

On Tue, Apr 18, 2023 at 03:13:01PM -0400, Johannes Weiner wrote:
> The different branches for retry are unnecessarily complicated. There
> is really only three outcomes: progress, skipped, failed. Also, the
> retry counter only applies to loops that made progress, move it there.
> 
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>
> ---
>  mm/page_alloc.c | 60 +++++++++++++++++--------------------------------
>  1 file changed, 20 insertions(+), 40 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index c3b7dc479936..18fa2bbba44b 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -4608,7 +4608,6 @@ should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
>  		     enum compact_priority *compact_priority,
>  		     int *compaction_retries)
>  {
> -	int max_retries = MAX_COMPACT_RETRIES;
>  	int min_priority;
>  	bool ret = false;
>  	int retries = *compaction_retries;

Think this breaks build because of trace_compact_retry and max_retries is
declared in a different scope on the next hunk.

Again, move this to a preparation series. I didn't actually think about
this patch at all because I'm trying to reach the main purpose of the series
and it's now late on a Friday so I'll probably fail or forget by Monday.

-- 
Mel Gorman
SUSE Labs