From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4059 invoked by alias); 27 Feb 2014 21:46:16 -0000 Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org Received: (qmail 4047 invoked by uid 89); 27 Feb 2014 21:46:16 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.4 required=5.0 tests=AWL,BAYES_00,KHOP_BIG_TO_CC autolearn=no version=3.3.2 X-HELO: mga11.intel.com Received: from mga11.intel.com (HELO mga11.intel.com) (192.55.52.93) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 27 Feb 2014 21:46:15 +0000 Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga102.fm.intel.com with ESMTP; 27 Feb 2014 13:46:13 -0800 X-ExtLoop1: 1 Received: from tassilo.jf.intel.com (HELO tassilo.localdomain) ([10.7.201.86]) by fmsmga002.fm.intel.com with ESMTP; 27 Feb 2014 13:45:48 -0800 Received: by tassilo.localdomain (Postfix, from userid 1000) id 0C18E301B5F; Thu, 27 Feb 2014 13:45:48 -0800 (PST) From: Andi Kleen To: Masami Hiramatsu Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Ananth N Mavinakayanahalli , Sandeepa Prabhu , Frederic Weisbecker , x86@kernel.org, Steven Rostedt , fche@redhat.com, mingo@redhat.com, systemtap@sourceware.org, "H. Peter Anvin" , Thomas Gleixner Subject: Re: [PATCH -tip v7 24/26] kprobes: Enlarge hash table to 4096 entries References: <20140227073315.20992.6174.stgit@ltc230.yrl.intra.hitachi.co.jp> <20140227073414.20992.16882.stgit@ltc230.yrl.intra.hitachi.co.jp> Date: Thu, 27 Feb 2014 21:46:00 -0000 In-Reply-To: <20140227073414.20992.16882.stgit@ltc230.yrl.intra.hitachi.co.jp> (Masami Hiramatsu's message of "Thu, 27 Feb 2014 16:34:14 +0900") Message-ID: <87y50wut4j.fsf@tassilo.jf.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-SW-Source: 2014-q1/txt/msg00196.txt.bz2 Masami Hiramatsu writes: > Currently, since the kprobes expects to be used > with less than 100 probe points, its hash table > just has 64 entries. This is too little to handle > several thousands of probes. > Enlarge this to 4096 entires which just consumes > 32KB (on 64bit arch) for better scalability. 32K for a debug feature that most systems never use seems too large to me. First can you check if smaller hash tables work too (perhaps with a better hash, like jhash) And then if you enlarge the table please allocate it dynamically on the first use. -Andi -- ak@linux.intel.com -- Speaking for myself only