From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757275AbZILCcl (ORCPT ); Fri, 11 Sep 2009 22:32:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757230AbZILCcl (ORCPT ); Fri, 11 Sep 2009 22:32:41 -0400 Received: from mail-yx0-f176.google.com ([209.85.210.176]:48988 "EHLO mail-yx0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757227AbZILCck (ORCPT ); Fri, 11 Sep 2009 22:32:40 -0400 Message-ID: <4AAB065D.3070602@vflare.org> Date: Sat, 12 Sep 2009 07:54:29 +0530 From: Nitin Gupta Reply-To: ngupta@vflare.org User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.1) Gecko/20090814 Fedora/3.0-2.6.b3.fc11 Thunderbird/3.0b3 MIME-Version: 1.0 To: Andrew Morton CC: Ed Tomlinson , Hugh Dickins , Pekka Enberg , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-mm-cc Subject: Re: [PATCH 0/4] compcache: in-memory compressed swapping v2 References: <200909100215.36350.ngupta@vflare.org> <200909100332.55910.ngupta@vflare.org> In-Reply-To: <200909100332.55910.ngupta@vflare.org> 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, On 09/10/2009 03:32 AM, Nitin Gupta wrote: > Project home: http://compcache.googlecode.com/ > > * Changelog: v2 vs initial revision > - Use 'struct page' instead of 32-bit PFNs in ramzswap driver and xvmalloc. > This is to make these 64-bit safe. > - xvmalloc is no longer a separate module and does not export any symbols. > Its compiled directly with ramzswap block driver. This is to avoid any > last bit of confusion with any other allocator. > - set_swap_free_notify() now accepts block_device as parameter instead of > swp_entry_t (interface cleanup). > - Fix: Make sure ramzswap disksize matches usable pages in backing swap file. > This caused initialization error in case backing swap file had intra-page > fragmentation. > > Can anyone please review these patches for possible inclusion in 2.6.32? Sorry for the weird email threading. Thanks, Nitin > It creates RAM based block devices which can be used (only) as swap disks. > Pages swapped to these disks 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 for a > given amount of memory. > > It can create multiple ramzswap devices (/dev/ramzswapX, X = 0, 1, 2, ...). > Each of these devices can have separate backing swap (file or disk partition) > which is used when incompressible page is found or memory limit for device is > reached. > > A separate userspace utility called rzscontrol is used to manage individual > ramzswap devices. > > * Testing notes > > Tested on x86, x64, ARM > ARM: > - Cortex-A8 (Beagleboard) > - ARM11 (Android G1) > - OMAP2420 (Nokia N810) > > * Performance > > All performance numbers/plots can be found at: > http://code.google.com/p/compcache/wiki/Performance > > Below is a summary of this data: > > General: > - Swap R/W times are reduced from milliseconds (in case of hard disks) > down to microseconds. > > Positive cases: > - Shows 33% improvement in 'scan' benchmark which allocates given amount > of memory and linearly reads/writes to this region. This benchmark also > exposes bottlenecks in ramzswap code (global mutex) due to which this gain > is so small. > - On Linux thin clients, it gives the effect of nearly doubling the amount of > memory. > > Negative cases: > Any workload that has active working set w.r.t. filesystem cache that is > nearly equal to amount of RAM while has minimal anonymous memory requirement, > is expected to suffer maximum loss in performance with ramzswap enabled. > > Iozone filesystem benchmark can simulate exactly this kind of workload. > As expected, this test shows performance loss of ~25% with ramzswap. > > (Sorry for long patch[2/4] but its now very hard to split it up). > > Documentation/blockdev/00-INDEX | 2 + > Documentation/blockdev/ramzswap.txt | 50 ++ > drivers/block/Kconfig | 22 + > drivers/block/Makefile | 1 + > drivers/block/ramzswap/Makefile | 3 + > drivers/block/ramzswap/ramzswap_drv.c | 1529 +++++++++++++++++++++++++++++++++ > drivers/block/ramzswap/ramzswap_drv.h | 183 ++++ > drivers/block/ramzswap/xvmalloc.c | 533 ++++++++++++ > drivers/block/ramzswap/xvmalloc.h | 30 + > drivers/block/ramzswap/xvmalloc_int.h | 86 ++ > include/linux/ramzswap_ioctl.h | 51 ++ > include/linux/swap.h | 5 + > mm/swapfile.c | 34 + > 13 files changed, 2529 insertions(+), 0 deletions(-) > _______________________________________________ >