Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757204AbbLCAw3 (ORCPT ); Wed, 2 Dec 2015 19:52:29 -0500 Received: from mail-pf0-f178.google.com ([209.85.192.178]:35360 "EHLO mail-pf0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754717AbbLCAw2 (ORCPT ); Wed, 2 Dec 2015 19:52:28 -0500 Message-ID: <565F924A.7050706@linaro.org> Date: Wed, 02 Dec 2015 16:52:26 -0800 From: "Shi, Yang" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Dave Hansen , akpm@linux-foundation.org, rostedt@goodmis.org, mingo@redhat.com CC: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linaro-kernel@lists.linaro.org Subject: Re: [PATCH V2 2/7] mm/gup: add gup trace points 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> <565F88B9.10306@linaro.org> In-Reply-To: <565F88B9.10306@linaro.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2165 Lines: 73 On 12/2/2015 4:11 PM, Shi, Yang wrote: > On 12/2/2015 3:36 PM, 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. > > Thanks for the suggestion, will move it to the last. > >> >>> @@ -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? > > I think it should be feasible. kmem_cache_alloc trace event could show > return value. I'm supposed gup trace events should be able to do the > same thing. Just did a quick test, it is definitely feasible. Please check the below test log: trace-cmd-200 [000] 99.221486: gup_get_user_pages: start=8000000ff0 nr_pages=1 ret=1 trace-cmd-200 [000] 99.223215: gup_get_user_pages: start=8000000fdb nr_pages=1 ret=1 trace-cmd-200 [000] 99.223298: gup_get_user_pages: start=8000000ed0 nr_pages=1 ret=1 nr_pages is the number of pages requested by the gup, ret is the return value. If nobody has objection, I will add it into V3. Regards, Yang > > Regards, > Yang > >> > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/