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Subject: Re: [RFC PATCH 3/3] mm: compaction: Fix the migration stats in
 trace_mm_compaction_migratepages()
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     akpm@linux-foundation.org, mingo@redhat.com, ziy@nvidia.com,
        shy828301@gmail.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
References: <cover.1635936218.git.baolin.wang@linux.alibaba.com>
 <6fac1a89862b6a8bda4314d1f51380862a6fa986.1635936218.git.baolin.wang@linux.alibaba.com>
 <20211103094232.32a14cf0@gandalf.local.home>
From:   Baolin Wang <baolin.wang@linux.alibaba.com>
Message-ID: <b1ec38a9-7513-bd18-9243-60f92eaf0d07@linux.alibaba.com>
Date:   Thu, 4 Nov 2021 17:18:52 +0800
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On 2021/11/3 21:42, Steven Rostedt wrote:
> On Wed,  3 Nov 2021 18:51:16 +0800
> Baolin Wang <baolin.wang@linux.alibaba.com> wrote:
> 
>> @@ -2398,10 +2399,10 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
>>   
>>   		err = migrate_pages(&cc->migratepages, compaction_alloc,
>>   				compaction_free, (unsigned long)cc, cc->mode,
>> -				MR_COMPACTION, NULL);
>> +				MR_COMPACTION, &nr_succeeded);
>>   
>> -		trace_mm_compaction_migratepages(cc->nr_migratepages, err,
>> -							&cc->migratepages);
>> +		trace_mm_compaction_migratepages(cc->nr_migratepages,
>> +						 nr_succeeded);
> 
> Also, I'm surprised you don't just pass in 'cc' and do the dereferencing in
> the trace event macro. Accessing the pointers from the trace event and not
> dereferencing them to the tracepoint function moves the changes out of line
> here and helps with I$.
> 
> You could improve some of the other tracepoints that dereference 'cc' as
> well in that file.

Sure. Will do in a separate patch.

> 
> But as for this change, I'm good with it.
> 
> For the tracing aspect:
> 
> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> 

Thanks.