linux-kernel - Re: [PATCH 2/2] mm/vmscan: make sure wakeup

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Message-ID: <20220329235900.3slpqbgjqgjv4y2e@master>
Date:   Tue, 29 Mar 2022 23:59:00 +0000
From:   Wei Yang <richard.weiyang@...il.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Wei Yang <richard.weiyang@...il.com>,
        "Huang, Ying" <ying.huang@...el.com>, akpm@...ux-foundation.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        mgorman@...hsingularity.net
Subject: Re: [PATCH 2/2] mm/vmscan: make sure wakeup_kswapd with managed zone

On Tue, Mar 29, 2022 at 03:22:51AM +0100, Matthew Wilcox wrote:
>On Tue, Mar 29, 2022 at 01:52:30AM +0000, Wei Yang wrote:
>> @@ -1985,14 +1985,13 @@ static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
>>  			continue;
>>  
>>  		/* Avoid waking kswapd by allocating pages_to_migrate pages. */
>> -		if (!zone_watermark_ok(zone, 0,
>> +		if (zone_watermark_ok(zone, 0,
>>  				       high_wmark_pages(zone) +
>>  				       nr_migrate_pages,
>>  				       ZONE_MOVABLE, 0))
>
>Someone's done the silly thing of lining up all of these with spaces,
>so either all these lines also need to be shrunk by one space, or you
>need to break that convention and just go to a reasonable number of
>tabs.  I'd do it like this:
>
>		if (zone_watermark_ok(zone, 0,
>				high_wmark_pages(zone) + nr_migrate_pages,
>				ZONE_MOVABLE, 0))
>
>but not everybody would.
>
>> @@ -2040,16 +2040,11 @@ static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
>>  		return 0;
>>  
>>  	/* Avoid migrating to a node that is nearly full */
>> -	if (!migrate_balanced_pgdat(pgdat, nr_pages)) {
>> -		int z;
>> -
>> +	if ((zone = migrate_balanced_pgdat(pgdat, nr_pages))) {
>
>Linus had a rant about this style recently.  He much prefers:
>
>	zone = migrate_balanced_pgdat(pgdat, nr_pages);
>	if (zone) {
>
>(the exception is for while loops:
>
>	while ((zone = migrate_balanced_pgdat(pgdat, nr_pages)) != NULL)
>
>where he wants to see the comparison against NULL instead of the awkard
>double-bracket)

Matthew,

Thanks for your suggestion, I would change this later.

-- 
Wei Yang
Help you, Help me