On Thu, Sep 03, 2015 at 12:07:03PM +0530, Navin Parakkal wrote:
On Tue, Sep 1, 2015 at 7:21 PM, Mel Gorman <mgorman@suse.de> wrote:
On Fri, Aug 28, 2015 at 12:01:11PM -0700, Linda A. Walsh wrote:
Michal Kubecek wrote:
On Friday 28 of August 2015 10:34:48 Navin Parakkal wrote:
On Fri, Aug 28, 2015 at 9:20 AM, Jeff Mahoney <jeffm@suse.com> wrote:
1) Inertia i'll skip this one.
Well, you shouldn't. To change things, one should have good reason. The more intrusive the change, the stronger the arguments for it should be. Unless there is a substantial gain, the change is not worth the effort and the risk.
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The problem doesn't occur with Oracle systems because during backup they have ways to use direct I/O and many DBAs set that by default . Sounds like a good thing to do because backup is like read source and write dest in both in direct I/O. Your buffer caches hardly grow but when you don't you explicity specify direct i/o when you copy files of huge size like 1000 files of 1G or 10000 files of 100 MB , the buffer_head and ext4_inode_cache or xfs_inode_cache grows very fast.
When you are backing up TeraBytes of data ie full export and backup , i think it is better not to fill up the kernel caches that you are going to seldom use. Any thoughts on this ?
The madvise and fadvise calls are there to discard unnecessary data read during backup. There is a prototype wrapper that forces it to happen at https://code.google.com/p/pagecache-mangagement/. Alternatively, a backup running inside a memcg would not be able to fill the memory with unnecessary data as it would be forced to reclaim in a timely fashion. It's not a problem that's directly related to either SLAB or SLUB as the page reclaim and shrinker interface that handles both remains the same. There may be an indirect problem when freeing many millions of slab objects at the same time but a soft lockup in such a path would likely be fixable with a cond_resched() call at the correct time. -- Mel Gorman SUSE Labs -- To unsubscribe, e-mail: opensuse-kernel+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-kernel+owner@opensuse.org