From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f170.google.com (mail-ig0-f170.google.com [209.85.213.170]) by kanga.kvack.org (Postfix) with ESMTP id 4747B6B0255 for ; Wed, 2 Dec 2015 23:13:51 -0500 (EST) Received: by igbxm8 with SMTP id xm8so3754255igb.1 for ; Wed, 02 Dec 2015 20:13:51 -0800 (PST) Received: from cdptpa-oedge-vip.email.rr.com (cdptpa-outbound-snat.email.rr.com. [107.14.166.225]) by mx.google.com with ESMTP id t82si10324470ioe.111.2015.12.02.20.13.50 for ; Wed, 02 Dec 2015 20:13:50 -0800 (PST) Date: Wed, 2 Dec 2015 23:13:48 -0500 From: Steven Rostedt Subject: Re: [PATCH V2 2/7] mm/gup: add gup trace points Message-ID: <20151202231348.7058d6e2@grimm.local.home> In-Reply-To: <565F8092.7000001@intel.com> References: <1449096813-22436-1-git-send-email-yang.shi@linaro.org> <1449096813-22436-3-git-send-email-yang.shi@linaro.org> <565F8092.7000001@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Yang Shi , akpm@linux-foundation.org, mingo@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linaro-kernel@lists.linaro.org On Wed, 2 Dec 2015 15:36:50 -0800 Dave Hansen wrote: > On 12/02/2015 02:53 PM, Yang Shi wrote: > > diff --git a/mm/gup.c b/mm/gup.c > > index deafa2c..10245a4 100644 > > --- a/mm/gup.c > > +++ b/mm/gup.c > > @@ -13,6 +13,9 @@ > > #include > > #include > > > > +#define CREATE_TRACE_POINTS > > +#include > > + > > #include > > #include > > This needs to be _the_ last thing that gets #included. Otherwise, you > risk colliding with any other trace header that gets implicitly included > below. Agreed. > > > @@ -1340,6 +1346,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, > > start, len))) > > return 0; > > > > + trace_gup_get_user_pages_fast(start, nr_pages, write, pages); > > + > > /* > > * Disable interrupts. We use the nested form as we can already have > > * interrupts disabled by get_futex_key. > > It would be _really_ nice to be able to see return values from the > various gup calls as well. Is that feasible? Only if you rewrite the functions to have a single return code path that we can add a tracepoint too. Or have a wrapper function that gets called directly that calls these functions internally and the tracepoint can trap the return value. I can probably make function_graph tracer give return values, although it will give a return value for void functions as well. And it may give long long returns for int returns that may have bogus data in the higher bits. -- Steve -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org