From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f176.google.com (mail-pf0-f176.google.com [209.85.192.176]) by kanga.kvack.org (Postfix) with ESMTP id 245346B0038 for ; Wed, 2 Dec 2015 19:52:29 -0500 (EST) Received: by pfdd184 with SMTP id d184so2954216pfd.3 for ; Wed, 02 Dec 2015 16:52:28 -0800 (PST) Received: from mail-pa0-x234.google.com (mail-pa0-x234.google.com. [2607:f8b0:400e:c03::234]) by mx.google.com with ESMTPS id bm5si8073065pad.107.2015.12.02.16.52.28 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 02 Dec 2015 16:52:28 -0800 (PST) Received: by padhx2 with SMTP id hx2so55512533pad.1 for ; Wed, 02 Dec 2015 16:52:28 -0800 (PST) Message-ID: <565F924A.7050706@linaro.org> Date: Wed, 02 Dec 2015 16:52:26 -0800 From: "Shi, Yang" MIME-Version: 1.0 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: owner-linux-mm@kvack.org List-ID: 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 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, 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