From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751885AbdAMQQX (ORCPT ); Fri, 13 Jan 2017 11:16:23 -0500 Received: from smtprelay0119.hostedemail.com ([216.40.44.119]:37948 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750906AbdAMQQW (ORCPT ); Fri, 13 Jan 2017 11:16:22 -0500 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::,RULES_HIT:41:355:379:541:599:800:960:968:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2393:2553:2559:2562:3138:3139:3140:3141:3142:3352:3622:3865:3866:3867:3868:3870:3871:3872:3874:4362:5007:6261:7875:8603:8660:9040:10004:10400:10848:10967:11026:11232:11658:11914:12663:12740:12760:12895:13069:13148:13161:13229:13230:13311:13357:13439:14096:14097:14181:14659:14721:21080:21451:30041:30051:30054:30070:30090:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:3,LUA_SUMMARY:none X-HE-Tag: work07_1a3577a240518 X-Filterd-Recvd-Size: 1984 Date: Fri, 13 Jan 2017 11:16:18 -0500 From: Steven Rostedt To: Namhyung Kim Cc: LKML , Ingo Molnar Subject: Re: [RFC/PATCH] ftrace: Allow to change size of function graph filters Message-ID: <20170113111618.53709bf8@gandalf.local.home> In-Reply-To: <20170113042243.15259-1-namhyung@kernel.org> References: <20170113042243.15259-1-namhyung@kernel.org> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 13 Jan 2017 13:22:43 +0900 Namhyung Kim wrote: > It's currently fixed to 32 and it ignores when user gives a pattern > which match to functions more than the size. So filtering like all > system calls or many functions with common prefix cannot be set all. > Not sure this is right though. Yes it's small, and there's a reason for it. So I'm giving a conditional nack to the patch. > > This patch adds 'graph_filter_size' file in the tracefs to adjust the > size. It can be changed only if the current tracer is not set. > > Signed-off-by: Namhyung Kim The condition is, we need to fix ftrace_graph_addr() first. for (i = 0; i < ftrace_graph_count; i++) { That gets called at every function being traced. See where I'm heading with that? ;-) We need to create a hash table or binary search first and make that function handle a large ftrace_graph_count before implementing your patch. Remove the linear search, replace it with either a binary search or a hash. But an O(n) algorithm at every function call is out of the question. Thanks! -- Steve