From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH 2/3] DEBUGFS: Add per cpu counters Date: Tue, 6 Dec 2011 09:17:51 -0800 Message-ID: <20111206171751.GA15062@alboin.jf.intel.com> References: <1322851407-17182-1-git-send-email-andi@firstfloor.org> <1322851407-17182-3-git-send-email-andi@firstfloor.org> <20111206114438.GA17186@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andi Kleen , "greg@kroah.com" , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" To: Wu Fengguang Return-path: Content-Disposition: inline In-Reply-To: <20111206114438.GA17186@localhost> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Tue, Dec 06, 2011 at 07:44:38PM +0800, Wu Fengguang wrote: > > +#include > > +#include > > +#include > > + > > +/* OPEN: implement module support */ > > Yeah, I think the module support would benefit my case as well. > > To support module users, init_counters() will be exported with the > __start___debugfs/__stop___debugfs hard coding removed. Then I'll be > call it from the readahead initilization code: No, the module loader should take care of this: look for the magic section, register it. This is already done for other magic sections and not too difficult, i just didn't write the code so far. Then the DEFINE_* macros would work seamlessly in modules too. Do you really need it for the readahead code? I thought that was builtin. > > DEFINE_PER_CPU(unsigned long[RA_PATTERN_MAX][RA_ACCOUNT_MAX], ra_counter); > struct debugfs_counter ra_pcpu_counter[RA_PATTERN_MAX][RA_ACCOUNT_MAX]; > > // init ra_pcpu_counter in a loop > for each pattern > init_counters(ra_pcpu_counter[pattern], ra_pcpu_counter[pattern+1]); Ok so you need arrays. The idea is to not call some init function, but just put it into section and let the init code walk it. Should probably have a macro that handles arrays nicely. > > +static int show_debugfs_counter(struct seq_file *m, void *arg) > > +{ > > + int n; > > + n = dump_counters(m, __start___debugfs, __stop___debugfs, m->private); > > That hard coded __start___debugfs/__stop___debugfs is OK for POC, and > will need to be improved to work with multiple users in kernel. For Modules it obviously has to walk a list. It's a straight forward extension. I don't think it should allow everyone to register their own lists, that doesn't make sense because they could as well create the debug files themselves. -Andi