From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <19980306154019.51826@Elf.mj.gts.cz> Date: Fri, 6 Mar 1998 15:40:19 +0100 From: Pavel Machek Subject: Re: [PATCH] kswapd fix & logic improvement References: <19980304093300.08111@Elf.mj.gts.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: ; from Benjamin C.R. LaHaise on Fri, Mar 06, 1998 at 04:06:22AM -0500 Sender: owner-linux-mm@kvack.org To: "Benjamin C.R. LaHaise" Cc: Pavel Machek , Rik van Riel , "Michael L. Galbraith" , linux-mm , linux-kernel List-ID: Hi! > > > Not only that, but the network activity X induces puts additional stress > > > on an already low-memory system by allocating lots of unswappable memory. > > > When might we see Pavel's patches to the networking stack meant to get > > > swapping over TCP working, but I think they'll really help stability on > > > systems with low-memory and busy networks, get integrated? > > > > Sorry? My patches are usable only if you are trying to swap over > > network. They will not help on low-memory systems, unless that systems > > also lack hard-drives. It is usually much better to swap onto local > > drive than over network. > > If they're setup the way I think they are, you're mistaken. ;-) I'm > thinking of the pathelogical case where the system is thrown into a state > where atomic memory consumption is occurring faster than the system can > free up memory. This could occur on a system with, say 100Mbps ethernet > and a low-end IDE drive (~5-7MBps peak) if we're using TCP with large > windows and have a *large* number of sockets open and receiving data. > Incoming packets could consume up to 10MB of GFP_ATOMIC memory per second > - ouch! With your patch, once we hit a danger zone, the system starts > dropping network packets, right? No. I create new priority level ('GFP_NUCLEONIC') which is allowed to consume few last-resort pages. This pages will be used for networking, only, and they will be used only for that single socked used for swapping. > That way there will still be enough > memory for allocating buffer heads and such to swap out as > nescessary... I thought that current swapping is deadlock-free. Am I wrong? [I tried hard to make network swap deadlock-free. I trusted swap-to-disk code to be deadlock-free...] Pavel -- I'm really pavel@atrey.karlin.mff.cuni.cz. Pavel Look at http://atrey.karlin.mff.cuni.cz/~pavel/ ;-).