From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by rv-out-0910.google.com with SMTP id l15so553637rvb for ; Fri, 24 Aug 2007 00:12:16 -0700 (PDT) Message-ID: Date: Fri, 24 Aug 2007 00:12:15 -0700 From: mike Subject: Re: Drop caches - is this safe behavior? In-Reply-To: <46CE7211.2010708@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <46CE3617.6000708@redhat.com> <1187930857.6406.12.camel@norville.austin.ibm.com> <46CE69DE.9040807@redhat.com> <46CE7211.2010708@redhat.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Chris Snook Cc: Dave Kleikamp , linux-mm@kvack.org List-ID: On 8/23/07, Chris Snook wrote: > I think the caches you had in mind were the ones that would be dropped > by echoing '1' into /proc/sys/vm/drop_caches, not the ones that would be > dropped by echoing '2' into it. If you were dropping pagecache every > five minutes, it would kill your performance as you described. As for > the question of safety, '3' should also be safe, but terrible for > performance, as it does all the harm of '1', plus some. actually right now the performance seems to be good - using "2" i'm willing to try "1" as well, as well as try the cache pressure one. i don't really know what caches i am clearing, but it seems that i get bottlenecked by something. restarting my webserver/php engines usually clears it up, so it seems like it is a buildup of something - and it always seems to be when memory is tight... > I'm not familiar with the "atsar" implementation, but it appears to be > an alternate implementation of the same thing. It's an excellent tool > for long-term workload profiling. actually, this might be a better method - is there any way to view the contents of the cache? or figure out what exactly is sitting in there/why my machine thinks it needs to cache 2 gigs of files so quickly? -- 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