Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 2 Feb 2002 07:34:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 2 Feb 2002 07:34:26 -0500 Received: from 167.imtp.Ilyichevsk.Odessa.UA ([195.66.192.167]:34826 "EHLO Port.imtp.ilyichevsk.odessa.ua") by vger.kernel.org with ESMTP id ; Sat, 2 Feb 2002 07:34:09 -0500 Message-Id: <200202021232.g12CWat01313@Port.imtp.ilyichevsk.odessa.ua> Content-Type: text/plain; charset=US-ASCII From: Denis Vlasenko Reply-To: vda@port.imtp.ilyichevsk.odessa.ua To: Arnaldo Carvalho de Melo Subject: Re: [PATCH] Re: crc32 and lib.a (was Re: [PATCH] nbd in 2.5.3 does Date: Sat, 2 Feb 2002 14:32:38 -0200 X-Mailer: KMail [version 1.3.2] Cc: linux-kernel@vger.kernel.org In-Reply-To: <20020131.145904.41634460.davem@redhat.com> <20020131232119.GN10772@conectiva.com.br> In-Reply-To: <20020131232119.GN10772@conectiva.com.br> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 31 January 2002 21:21, Arnaldo Carvalho de Melo wrote: > Em Thu, Jan 31, 2002 at 11:24:10PM +0000, Alan Cox escreveu: > > What I'd much rather see if this is an issue is: > > > > bool 'Do you want to customise for a very small system' > > > > which auto enables all the random small stuff if you say no, and goes > > much deeper into options if you say yes. > > heh, after I've read that you managed to boot 2.4 + rmap in a machine with > just 4 MB after tweaking some table sizes I thought about devoting some > time to identify those tables and making them options in make *config, with > even a nice CONFIG_TINY, like you said 8) > > I'll eventually do this, and I'd appreciate if people send me suggestions > of tables/data structures that can be trimmed/reduced. Yeah, I'll take a > look at the .config files used in the embedded distros. One of inhabitants of my "Don't delete!" mail folder: Re: Limited RAM - how to save it? From: Lars Brinkhoff To: Jan-Benedict Glaw Cc: linux-kernel@vger.kernel.org Jan-Benedict Glaw writes: > I'm working on a 4MB linux system (for a customer) which has quite > limited resources [...] If you've got further ideas on getting the > kernel a bit smaller, would be nice to get a mail dropped... I started a port of Linux 2.3.99 to a MIPS device which usually has 2M flash and 4M RAM. To reduce the size of the text and data sections, I sorted the output of the "size" command and investigated the files with the largest sections. These are the memory-saving changes I arrived at. They are not really tested, so some of them may break some functionality. Also, I don't know whether they apply to the current kernels. fs/dcache.c Changed HASH_BITS from 14 to 8. This reduces the size of the cache from 128K to 2K. fs/inode.c Changed HASH_BITS from 14 to 8. This reduces the size of the cache from 128K to 2K. include/linux/blk.h Changed NR_REQUEST from 256 to 16. This reduces the number of requests that can be queued. The size of the queue is reduced from 16K to 1K. include/linux/major.h Changed MAX_BLKDEV and MAX_CHRDEV from 256 to 10 and 20, respectively. This reduces the number of block and character devices and saves about 40K. kernel/printk.c Changed LOG_BUF_LEN from 16384 bytes to 2048 bytes. include/linux/tty.h Changed NR_PTYS and NR_LDISCS from 256 and 16, respectively, to 16 and 4, respectively. Saved about 12K. Warning: this change may break the pty driver, in which case further modifications will have to be done to drivers/char/pty.c. kernel/panic.c Changed a buffer from 1024 bytes to 200 bytes. include/linux/sched.h Changed PIDHASH_SZ from 1024 to 16, which saves 1008 bytes. include/linux/mmzone.h NR_GPFINDEX from 0x100 to 0x10. Saves 4800 bytes, but I'm not sure it doesn't break anything. net/Makefile, net/socket.c, net/nosocket.c Replacing socket.c with nosocket.c, a file containing dummy replacement functions for those in socket.c, saves about 24K. Warning: this disables the socket API entirely, but it is currently not used in the product. mm/Makefile, mm/swapfile.c, mm/swap_state.c, mm/noswapfile.c, mm/noswap_state.c Replacing swapfile.c with noswapfile.c, and swap_state.c with noswap_state.c saves about 12K. The no*.c files contains empty replacement functions. Warning: this disables swapping of anonymous memory, which isn't used in the product. But note that demand paging of executables still works. mm/Makefile, mm/mmap.c The functions in mmap.c could probably also be replaced by empty functions. Estimated saving: 9K (not included in the grand total below). *, CONFIG_MESSAGES Applying the CONFIG_MESSAGES patch and disabling all kernel messages saves about 80K. The CONFIG_MESSAGES patch was written by Graham Stoney . With all of the above, and only this enabled in .config: CONFIG_EXPERIMENTAL=y CONFIG_CPU_R3000=y CONFIG_CPU_LITTLE_ENDIAN=y CONFIG_ELF_KERNEL=y CONFIG_BINFMT_ELF=y CONFIG_MODULES=y CONFIG_MODVERSIONS=y CONFIG_KMOD=y CONFIG_CROSSCOMPILE=y , the kernel is down to about 550K. Here is the output of "size vmlinux". I think this is without the CONFIG_MESSAGES patch (it was long since I worked with this). text data bss dec hex filename 572128 41964 15860 629952 99cc0 vmlinux -- Lars Brinkhoff http://lars.nocrew.org/ Linux, GCC, PDP-10 Brinkhoff Consulting http://www.brinkhoff.se/ programming - 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/ - 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/