On Thu 25-10-12 04:57:11, Dave Hansen wrote: [...] > Here's the problem: Joe Kernel Developer gets a bug report, usually > something like "the kernel is slow", or "the kernel is eating up all my > memory". We then start going and digging in to the problem with the > usual tools. We almost *ALWAYS* get dmesg, and it's reasonably common, > but less likely, that we get things like vmstat along with such a bug > report. > > Joe Kernel Developer digs in the statistics or the dmesg and tries to > figure out what happened. I've run in to a couple of cases in practice > (and I assume Michal has too) where the bug reporter was using > drop_caches _heavily_ and did not realize the implications. It was > quite hard to track down exactly how the page cache and dentries/inodes > were getting purged. Yes, very same here. Not that I would meet issues like that often but it happened in the past few times and it was always a lot of burnt time. > There are rarely oopses involved in these scenarios. > > The primary goal of this patch is to make debugging those scenarios > easier so that we can quickly realize that drop_caches is the reason our > caches went away, not some anomalous VM activity. A secondary goal is > to tell the user: "Hey, maybe this isn't something you want to be doing > all the time." -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>