Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 4 Nov 2000 15:03:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 4 Nov 2000 15:02:58 -0500 Received: from smtpde02.sap-ag.de ([194.39.131.53]:38646 "EHLO smtpde02.sap-ag.de") by vger.kernel.org with ESMTP id ; Sat, 4 Nov 2000 15:02:48 -0500 To: Rik van Riel Cc: Jonathan George , "'matthew@mattshouse.com'" , "'linux-kernel@vger.kernel.org'" Subject: Re: 2.4.0-test10 Sluggish After Load In-Reply-To: From: Christoph Rohland Date: 04 Nov 2000 21:04:10 +0100 Message-ID: User-Agent: Gnus/5.0807 (Gnus v5.8.7) XEmacs/21.1 (Capitol Reef) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Lines: 54 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi Rik, Rik van Riel writes: > Indeed, shared memory performance still sucks rocks. No, it's not a performance problem. It is a hard lockup problem on highmem machines. I do see two problems here: 1) shm_swap_core does not handle the failure of prepare_higmem_swapout right and basically cannot do so. It gets called zone independant and should probably get called per zone. At least it has to react: If the lowmem zone is full it should not try to swap out highmem pages. I have a little workaround for that. Unfortunately this is not the whole thing: 2) Apparently the vm does not handle the case, where it has hardly any pages in the queues. My machine locks up with the following memory numbers: SysRq: Show Memory Mem-info: Free pages: 2560kB ( 1028kB HighMem) ( Active: 5, inactive_dirty: 27, inactive_clean: 27, free: 640 (638 1276 1914) )0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 1*512kB 0*1024kB 0*2048kB = 512kB) 7*4kB 14*8kB 1*16kB 1*32kB 1*64kB 0*128kB 1*256kB 1*512kB 0*1024kB 0*2048kB = 1020kB) 3*4kB 1*8kB 1*16kB 1*32kB 1*64kB 1*128kB 1*256kB 1*512kB 0*1024kB 0*2048kB = 1028kB) Swap cache: add 31231, delete 31218, find 21433/21531 Free swap: 1961028kB 2162688 pages of RAM 1867776 pages of HIGHMEM 102296 reserved pages 1204551 pages shared 13 pages swap cached 0 pages in page table cache Buffer memory: 100kB CLEAN: 2 buffers, 8 kbyte, 2 used (last=2), 0 locked, 0 protected, 0 dirty LOCKED: 25 buffers, 100 kbyte, 25 used (last=25), 2 locked, 0 protected, 0 dirty You see: you only have 5+27+27=59 pages under your control... > I have not had time to fix this and I'm afraid I probably > won't have time to fix this in the near future. I'm willing > to give some advice to people who do want to take on the job > of fixing SHM performance, though.. As you know I started this some time before, but nobody helped me in integrating it into the rest of the VM :-( Unfortunately my time is very limited, but I probably would give it a second try since I think shm swapping should work. But I think a clean integration is a 2.5 issue. Greetings Christoph - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/