From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 513 invoked by alias); 15 Mar 2006 13:38:38 -0000 Received: (qmail 502 invoked by uid 22791); 15 Mar 2006 13:38:37 -0000 X-Spam-Status: No, hits=-2.3 required=5.0 tests=AWL,BAYES_00,UNPARSEABLE_RELAY X-Spam-Check-By: sourceware.org Received: from mail8.hitachi.co.jp (HELO mail8.hitachi.co.jp) (133.145.228.43) by sourceware.org (qpsmtpd/0.31) with ESMTP; Wed, 15 Mar 2006 13:38:35 +0000 Received: from mlsv10.hitachi.co.jp (unknown [133.145.228.16]) by mail8.hitachi.co.jp (Postfix) with ESMTP id 43B2537C83 for ; Wed, 15 Mar 2006 22:38:32 +0900 (JST) Received: from mfilter-s5.hitachi.co.jp by mlsv10.hitachi.co.jp (8.12.11/8.12.11) id k2FDcWUN006803; Wed, 15 Mar 2006 22:38:32 +0900 Received: from vshuts4.hitachi.co.jp (unverified) by mfilter-s5.hitachi.co.jp (Content Technologies SMTPRS 4.3.17) with SMTP id ; Wed, 15 Mar 2006 22:38:32 +0900 Received: from hsdlgw92.sdl.hitachi.co.jp ([133.144.7.20]) by vshuts4.hitachi.co.jp with SMTP id M2006031522385024060 ; Wed, 15 Mar 2006 22:38:52 +0900 Received: from vgate2.sdl.hitachi.co.jp by hsdlgw92.sdl.hitachi.co.jp (8.9.3/3.7W01100113) id WAA22211; Wed, 15 Mar 2006 22:38:29 +0900 Received: from maila.sdl.hitachi.co.jp ([133.144.14.196]) by vgate2.sdl.hitachi.co.jp (SAVSMTP 3.1.1.32) with SMTP id M2006031522382915007 ; Wed, 15 Mar 2006 22:38:29 +0900 Received: from [192.168.16.226] ([192.168.16.226]) by maila.sdl.hitachi.co.jp (8.13.1/3.7W04031011) with ESMTP id k2FDcTWH020077; Wed, 15 Mar 2006 22:38:29 +0900 Message-ID: <441818D2.1010802@sdl.hitachi.co.jp> Date: Wed, 15 Mar 2006 13:38:00 -0000 From: Masami Hiramatsu User-Agent: Thunderbird 1.5 (Windows/20051201) MIME-Version: 1.0 To: "bibo,mao" Cc: prasanna@in.ibm.com, systemtap@sources.redhat.com, Ananth N Mavinakayanahalli , "Keshavamurthy, Anil S" , Jim Keniston , Satoshi Oshima , Yumiko Sugita , Hideo Aoki , Maneesh Soni Subject: Re: [PATCH] kprobe-booster: boosting multi-probe References: <43F5C22C.5050702@sdl.hitachi.co.jp> <44151136.7020101@intel.com> <441578BF.6090001@sdl.hitachi.co.jp> <44162569.6060402@intel.com> In-Reply-To: <44162569.6060402@intel.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2006-q1/txt/msg00791.txt.bz2 Hi, bibo,mao wrote: > Masami Hiramatsu wrote: >> I think your patch enables booster even when preemption is >> enabled, and it may be dangerous. Some running processes can >> be preempted by another process when it is executing the codes in >> the instruction buffer. When the boosted-probe is deregistered, that >> instruction buffer is removed. Then, those preempted processes >> can't continue to run, because they can't back to the preempted address. >> So, I think, for the safety, the booster should NOT be enabled when >> preemption is enabled. >> Please fix it. > It actually is one problem, now I fix it. But actually most time kprobe > happen in preempt enable places, such as system call entry position, > then booster function will lose its effect. Sure, I know. There are some solutions for it. One of the my idea is to inhibit preemption in the instruction buffer by checking interruption address at the interrupt handler. However, I thought this should modify other kernel subsystem and the patch would become too complex. So, in the first release patch, I just disabled booster when preemption is enabled. After all, this patch seems good to me. Thanks for the hack. -- Masami HIRAMATSU 2nd Research Dept. Hitachi, Ltd., Systems Development Laboratory E-mail: hiramatu@sdl.hitachi.co.jp