Messages in this thread | | | Date | Mon, 29 Jul 2013 13:57:43 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH resend] drop_caches: add some documentation and info message |
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On Fri, 26 Jul 2013 14:44:29 +0200 Michal Hocko <mhocko@suse.cz> wrote:
> ... > > : There is plenty of anecdotal evidence and a load of blog posts > : suggesting that using "drop_caches" periodically keeps your system > : running in "tip top shape". Perhaps adding some kernel > : documentation will increase the amount of accurate data on its use. > : > : If we are not shrinking caches effectively, then we have real bugs. > : Using drop_caches will simply mask the bugs and make them harder > : to find, but certainly does not fix them, nor is it an appropriate > : "workaround" to limit the size of the caches. > : > : It's a great debugging tool, and is really handy for doing things > : like repeatable benchmark runs. So, add a bit more documentation > : about it, and add a little KERN_NOTICE. It should help developers > : who are chasing down reclaim-related bugs. > > ... > > --- 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?
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