From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756923AbZC2Dny (ORCPT ); Sat, 28 Mar 2009 23:43:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752210AbZC2Dnn (ORCPT ); Sat, 28 Mar 2009 23:43:43 -0400 Received: from ti-out-0910.google.com ([209.85.142.184]:4854 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751294AbZC2Dnn (ORCPT ); Sat, 28 Mar 2009 23:43:43 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:reply-to:user-agent:mime-version:to:cc:subject :content-type:content-transfer-encoding; b=VlGdaIJR91NEXHcdupbL/NCaaJFsxMnGJdBv+4khIqr1OkxWOlOl/biQRYYLDUSs2C ASd6zw7FH3nLMr4GPnpFXjqbh+mXTWNNN7vRrd1y1QWHQmFBQOqn+WZlSqzRz7fg/+I6 uEftpMfa3y7sFCcgB8jC7Nn0N5QkmJC05aWmY= Message-ID: <49CEEE5A.4080004@vflare.org> Date: Sun, 29 Mar 2009 09:13:22 +0530 From: Nitin Gupta Reply-To: ngupta@vflare.org User-Agent: Thunderbird 2.0.0.21 (Windows/20090302) MIME-Version: 1.0 To: Andrew Morton CC: Christoph Lameter , Pekka Enberg , Ed Tomlinson , linux-mm-cc@laptop.org, "linux-kernel@vger.kernel.org" Subject: [PATCH 0/3] compressed in-memory swapping take4 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Project home: http://compcache.googlecode.com It allows creating a RAM based block device which acts as swap disk. Pages swapped to this device are compressed and stored in memory itself. This is a big win over swapping to slow hard-disk which are typically used as swap disk. For flash, these suffer from wear-leveling issues when used as swap disk - so again its helpful. For swapless systems, it allows more apps to run. * Changelog: take4 vs take3 xvmalloc changes: - Fixed regression in take3 that caused ramzswap write failures. This happened due to error in find_block() where we did not do explicit cast to 'unsigned long' when checking for bits set in bitmap. Now changed it to use kernel build-in test_bit(). - Fix divide by zero error in proc read function. ramzswap changes: - Forward write requests to backing swap device if allocation for compressed page fails. - Code cleanups. (Please also see testing notes below). * Changelog: take3 vs take2 xvmalloc changes: - Use kernel defined macros and constants in xvmalloc and remove equivalent defines for ALIGN, roundup etc. - Use kernel bitops (set_bit, clear_bit) - Moved it to drivers/block since its not clear if it has any other user. ramzswap changes: - All instances of compcache renamed to ramzswap. Also renamed module to ramzswap - Renamed "backing_dev" parameter to "backing_swap" - Documentation changes to reflect above changes. - Remove "table index" from object header (4 bytes). This will be needed when memory defragmentation is implemented. So, avoid this (small) overhead for now. * Changelog: take2 vs initial revision: xvmalloc changes: - Use Linux kernel coding style for xvmalloc - Collapse all individual flag test/set/get to generic {test_set_get}_flag - Added BLOCK_NEXT() macro to reach next contiguous block - Other minor cleanups - no functional changes compcache block device code: - compcache core changes due to change in xvmalloc interface names * Testing notes: - Multiple cycles of 'scan' benchmark available at: http://linux-mm.org/PageReplacementTesting It does scans of anonymous mapped memory, both cyclic and use once. Config: Arch: x86 and x64 CPUs: 1/2, RAM: 512MB backing swap: 768MB, ramzswap memlimit: 76MB (15% of RAM). Continuously run 'scan' till it triggers 200K R/W operations on ramzswap. Any incompressible pages were correctly forwarded to backing swap device. cmd: ./scan 450 20 # scan over 450MB, 20 times. - Links to more performance numbers, use cases can be found at: http://lkml.org/lkml/2009/3/17/116 Thanks to Ed Tomlinson for reporting bug in 'take3' patches and to reviewers of previous versions. Thanks, Nitin