From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 27 Jun 2000 04:26:42 +0100 From: "Stephen C. Tweedie" Subject: Re: RSS guarantees and limits Message-ID: <20000627042642.D1065@redhat.com> References: <20000622221923.A8744@redhat.com> <20000624192245.A6617@saw.sw.com.sg> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20000624192245.A6617@saw.sw.com.sg>; from saw@saw.sw.com.sg on Sat, Jun 24, 2000 at 07:22:45PM +0800 Sender: owner-linux-mm@kvack.org Return-Path: To: Andrey Savochkin Cc: John Fremlin , linux-mm@kvack.org, Stephen Tweedie List-ID: Hi, On Sat, Jun 24, 2000 at 07:22:45PM +0800, Andrey Savochkin wrote: > > Small applications are not always good, as well as big are not bad. > We just want good memory service for those applications which we want to have > it :-) It hears like tautology, but that it. It's completely administrator > policy decision. Somewhat, but not entirely. Remember that we were talking about both RSS limits and RSS guarantees being dymamic. RSS guarantees for small processes (based on their fault activity, of course, so that idle small tasks can still be swapped out) are perhaps dependent on what those tasks are actually doing if the object is to have them compete against each other more fairly. However, RSS limits on the largest tasks in the system have an entirely different effect --- they prevent swap storms from overwhelming small tasks entirely, by placing more of the burden of the swapping on the large task. If a task is so large that it is thrashing, then removing a few 100K from its RSS doesn't usually have all that a dramatic effect on its performance. Remember, we'll only be doing this pruning if there is continuing memory pressure. If that large task becomes the only task wanting more memory again, we can let its RSS limit creep up again. That way, processes which just fit into memory on an idle system will continue to work just fine, but once we get memory contention, they won't stop the rest of the system from getting going again. Cheers, Stephen -- 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.eu.org/Linux-MM/