From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753614AbdKXNsM (ORCPT ); Fri, 24 Nov 2017 08:48:12 -0500 Received: from mx2.suse.de ([195.135.220.15]:58815 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753556AbdKXNsL (ORCPT ); Fri, 24 Nov 2017 08:48:11 -0500 Date: Fri, 24 Nov 2017 14:48:08 +0100 From: Michal Hocko To: Vaneet Narang Cc: Dmitry Vyukov , Maninder Singh , "kstewart@linuxfoundation.org" , "gregkh@linuxfoundation.org" , "pombredanne@nexb.com" , "jpoimboe@redhat.com" , "akpm@linux-foundation.org" , "vbabka@suse.cz" , "guptap@codeaurora.org" , "vinmenon@codeaurora.org" , AMIT SAHRAWAT , PANKAJ MISHRA , Lalit Mohan Tripathi , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , kasan-dev Subject: Re: Re: Re: [PATCH 1/1] stackdepot: interface to check entries and size of stackdepot. Message-ID: <20171124134808.ixyqzmzzyamja4ao@dhcp22.suse.cz> References: <20171124124429.juonhyw4xbqc65u7@dhcp22.suse.cz> <20171123162835.6prpgrz3qkdexx56@dhcp22.suse.cz> <1511347661-38083-1-git-send-email-maninder1.s@samsung.com> <20171124094108epcms5p396558828a365a876d61205b0fdb501fd@epcms5p3> <20171124095428.5ojzgfd24sy7zvhe@dhcp22.suse.cz> <20171124115707epcms5p4fa19970a325e87f08eadb1b1dc6f0701@epcms5p4> <20171124133025epcms5p7dc263c4a831552245e60193917a45b07@epcms5p7> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20171124133025epcms5p7dc263c4a831552245e60193917a45b07@epcms5p7> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 24-11-17 13:30:25, Vaneet Narang wrote: > Hi Michal, > > >> We have been getting similar kind of such entries and eventually > >> stackdepot reaches Max Cap. So we found this interface useful in debugging > >> stackdepot issue so shared in community. >   > >Then use it for internal debugging and provide a code which would scale > >better on smaller systems. We do not need this in the kernel IMHO. We do > >not merge all the debugging patches we use for internal development. > `  > Not just debugging but this information can also be used to profile and tune stack depot. > Getting count of stack entries would help in deciding hash table size and > page order used by stackdepot. How can you control that in runtime? > For less entries, bigger hash table and higher page order slabs might not be required as > maintained by stackdepot. As i already mentioned smaller size hashtable can be choosen and > similarly lower order pages can be used for slabs. > > If you think its useful, we can share scalable patch to configure below two values based on > number of stack entries dynamically. Exporting this data without having a way to control it is just not very useful for upstream kernel. If you can come up with some dynamic tuning then that might be interesting. But your patch doesn't seem useful outside of the development enviroment AFAICS. -- Michal Hocko SUSE Labs