linux-kernel - Re: [PATCH V2 2/2] mm: compaction: Limit the value of interface compact

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Message-ID: <cd60d29e-9512-dcc6-e72a-a4936fed42f5@suse.cz>
Date:   Wed, 8 Mar 2023 22:54:31 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     ye.xingchen@....com.cn, keescook@...omium.org, yzaikin@...gle.com,
        akpm@...ux-foundation.org, linmiaohe@...wei.com,
        chi.minghao@....com.cn, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH V2 2/2] mm: compaction: Limit the value of interface
 compact_memory

On 3/8/23 20:57, Luis Chamberlain wrote:
> On Wed, Mar 08, 2023 at 11:23:45AM +0100, Vlastimil Babka wrote:
>> >  {
>> > -	if (write)
>> > +	int ret;
>> > +
>> > +	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
>> > +	if (ret)
>> > +		return ret;
>> > +	if (write) {
>> > +		pr_info("compact_nodes start\n");
>> >  		compact_nodes();
>> > +		pr_info("compact_nodes end\n");
>> 
>> I'm not sure we want to start spamming the dmesg. This would make sense
>> if we wanted to deprecate the sysctl and start hunting for remaining
>> callers to be fixed. Otherwise ftrace can be used to capture e.g. the time.
> 
> Without that print, I don't think a custom proc handler is needed too,
> right? So what would simplify the code.

But we'd still call compact_nodes(), so that's not possible without a custom
handler, no?

>   Luis