Date: Tue, 30 Jul 2013 09:45:31 +0200
From: Michal Hocko <mhocko@suse.cz>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, dave.hansen@intel.com,
        kosaki.motohiro@jp.fujitsu.com, kamezawa.hiroyu@jp.fujitsu.com,
        bp@suse.de, Dave Hansen <dave@linux.vnet.ibm.com>
Subject: Re: [PATCH resend] drop_caches: add some documentation and info
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On Mon 29-07-13 13:57:43, Andrew Morton wrote:
> On Fri, 26 Jul 2013 14:44:29 +0200 Michal Hocko <mhocko@suse.cz> wrote:
[...]
> > --- a/fs/drop_caches.c
> > +++ b/fs/drop_caches.c
> > @@ -59,6 +59,8 @@ int drop_caches_sysctl_handler(ctl_table *table, int write,
> >  	if (ret)
> >  		return ret;
> >  	if (write) {
> > +		printk(KERN_INFO "%s (%d): dropped kernel caches: %d\n",
> > +		       current->comm, task_pid_nr(current), sysctl_drop_caches);
> >  		if (sysctl_drop_caches & 1)
> >  			iterate_supers(drop_pagecache_sb, NULL);
> >  		if (sysctl_drop_caches & 2)
> 
> How about we do
> 
> 	if (!(sysctl_drop_caches & 4))
> 		printk(....)
>
> so people can turn it off if it's causing problems?

I am OK with that  but can we use a top bit instead. Maybe we never have
other entities to drop in the future but it would be better to have a room for them
just in case. So what about using 1<<31 instead?


-- 
Michal Hocko
SUSE Labs
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