Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 13 Sep 2002 18:38:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 13 Sep 2002 18:38:34 -0400 Received: from air-2.osdl.org ([65.172.181.6]:10882 "EHLO wookie-t23.pdx.osdl.net") by vger.kernel.org with ESMTP id ; Fri, 13 Sep 2002 18:38:33 -0400 Subject: RE: Killing/balancing processes when overcommited From: "Timothy D. Witham" To: "Timothy D. Witham" Cc: jimsibley@earthlink.net, riel@conectiva.com.br, linux-kernel@vger.kernel.org, thunder@lightweight.ods.org In-Reply-To: <1031956299.2317.240.camel@wookie-t23.pdx.osdl.net> References: <1031956299.2317.240.camel@wookie-t23.pdx.osdl.net> Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Ximian Evolution 1.0.8 Date: 13 Sep 2002 15:38:23 -0700 Message-Id: <1031956703.1403.245.camel@wookie-t23.pdx.osdl.net> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3630 Lines: 96 On Fri, 2002-09-13 at 15:31, Timothy D. Witham wrote: > > On Fri, 2002-09-13 at 14:13, Jim Sibley wrote: > > > > > > Tim wrote: > > > There is another solution. And that is never >allocate memory unless > > >you have swap space. Yes, the issue is that you >need to have lots of > > >disk allocated to swap but on a big machine you >will have that space. > > > > How do you predict if a program is going to ask for more memory? Maybe it only > > needs additional memory for a short time and is a good citizen and gives it > > back? > > > > Well its been a bit so the details are fuzzy but you have a pointer Counter, I meant to say "a counter as to " instead of "a pointer to". :-) > to how much space you have left in you allocated swap and when you get > memory you decrement space and when you release memory in increment it > so that it indicates how much you have left. If you try and malloc > more than you free then you go and reserve another chunk of swap. > > > How much disk needs to be allocated for swap? In 32 bit, each logged in user > > is limited to 2 GB, so do we need 2 GB for each logged on user? 250 users, 500 > > GB of disk? > > > > It turns out that for the high load database machines this is about > 3 to 4 times the actual physical memory. > > > > In a 64 bit system, how much swap would you reserve? > > > > Same as 32 bit machines doesn't apply. > > > > Actually, another OS took this approach in the early 70's and this was quickly > > junked when they found out how much disk they really had to keep in reserve > > for paging. > > > > But there are many current OS's that do this and are quite successful. > > > > This way the offending process that asks for >more memory will be > > >the one that gets killed. Even if the 1st couple >of ones aren't the > > >misbehaving process eventually it will ask for >more memory and suffer > > >process execution. > > > > It may not be the "offending process" that is asking for more memory. How do > > you judge "offending?" > > > > In this case the offense is asking for more memory. So it is the > process that asks for more memory that goes away. Again sometimes > it will be an innocent bystander but hopefully it will eventually > be the process that is causing the problem. > > Many databases program for this condition. The stuff that absolutely > must be up and running preallocates all of the memory that it needs > at startup. Any new memory requests that are denied might cause a > transaction to fail but they won't bring down the whole database. > > Tim > > > > > > > > > -- > Timothy D. Witham - Lab Director - wookie@osdlab.org > Open Source Development Lab Inc - A non-profit corporation > 15275 SW Koll Parkway - Suite H - Beaverton OR, 97006 > (503)-626-2455 x11 (office) (503)-702-2871 (cell) > (503)-626-2436 (fax) > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Timothy D. Witham - Lab Director - wookie@osdlab.org Open Source Development Lab Inc - A non-profit corporation 15275 SW Koll Parkway - Suite H - Beaverton OR, 97006 (503)-626-2455 x11 (office) (503)-702-2871 (cell) (503)-626-2436 (fax) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/