From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <46CE69DE.9040807@redhat.com> Date: Fri, 24 Aug 2007 01:17:18 -0400 From: Chris Snook MIME-Version: 1.0 Subject: Re: Drop caches - is this safe behavior? References: <46CE3617.6000708@redhat.com> <1187930857.6406.12.camel@norville.austin.ibm.com> In-Reply-To: <1187930857.6406.12.camel@norville.austin.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Dave Kleikamp Cc: mike , linux-mm@kvack.org List-ID: Dave Kleikamp wrote: > On Thu, 2007-08-23 at 21:36 -0400, Chris Snook wrote: > >> If you think the system is doing the wrong thing (and it doesn't sound >> like it is) you should be tweaking the vm.swappiness sysctl. The >> default is 60, but lower values will make it behave more like you think >> it should be behaving, though you'll still probably see a tiny bit of >> swap usage. Of course, if your webservers are primarily serving up >> static content, you'll want a higher value, since swapping anonymous >> memory will leave more free for the pagecache you're primarily working with. > > swappiness deals with page cache, whereas writing "2" to drop_caches > cleans out the inode and dentry caches. Mike may be better off writing > a high number (say 10000) to /proc/sys/vm/vfs_cache_pressure. This > would cause inode and dentry cache to be reclaimed sooner than other > memory. > Thanks, I was confusing this with dropping pagecache. Mike -- Try Dave's suggestion to increase vm.vfs_cache_pressure. drop_pages should never be needed, regardless of which caches you're dropping. -- Chris -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org