From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f174.google.com (mail-io0-f174.google.com [209.85.223.174]) by kanga.kvack.org (Postfix) with ESMTP id 9EC586B0038 for ; Tue, 1 Dec 2015 19:18:29 -0500 (EST) Received: by ioc74 with SMTP id 74so28463147ioc.2 for ; Tue, 01 Dec 2015 16:18:29 -0800 (PST) Received: from smtprelay.hostedemail.com (smtprelay0094.hostedemail.com. [216.40.44.94]) by mx.google.com with ESMTPS id t10si1318545igr.54.2015.12.01.16.18.28 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 01 Dec 2015 16:18:29 -0800 (PST) Date: Tue, 1 Dec 2015 19:18:26 -0500 From: Steven Rostedt Subject: Re: [PATCH 1/7] trace/events: Add gup trace events Message-ID: <20151201191826.771bce5d@gandalf.local.home> In-Reply-To: <565E3650.4050209@linaro.org> References: <1449011177-30686-1-git-send-email-yang.shi@linaro.org> <1449011177-30686-2-git-send-email-yang.shi@linaro.org> <20151201185643.2ef6cd14@gandalf.local.home> <565E3650.4050209@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: "Shi, Yang" Cc: akpm@linux-foundation.org, mingo@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linaro-kernel@lists.linaro.org On Tue, 01 Dec 2015 16:07:44 -0800 "Shi, Yang" wrote: > On 12/1/2015 3:56 PM, Steven Rostedt wrote: > > On Tue, 1 Dec 2015 15:06:11 -0800 > > Yang Shi wrote: > > > >> page-faults events record the invoke to handle_mm_fault, but the invoke > >> may come from do_page_fault or gup. In some use cases, the finer event count > >> mey be needed, so add trace events support for: > >> > >> __get_user_pages > >> __get_user_pages_fast > >> fixup_user_fault > >> > >> Signed-off-by: Yang Shi > >> --- > >> include/trace/events/gup.h | 77 ++++++++++++++++++++++++++++++++++++++++++++++ > >> 1 file changed, 77 insertions(+) > >> create mode 100644 include/trace/events/gup.h > >> > >> diff --git a/include/trace/events/gup.h b/include/trace/events/gup.h > >> new file mode 100644 > >> index 0000000..37d18f9 > >> --- /dev/null > >> +++ b/include/trace/events/gup.h > >> @@ -0,0 +1,77 @@ > >> +#undef TRACE_SYSTEM > >> +#define TRACE_SYSTEM gup > >> + > >> +#if !defined(_TRACE_GUP_H) || defined(TRACE_HEADER_MULTI_READ) > >> +#define _TRACE_GUP_H > >> + > >> +#include > >> +#include > >> + > >> +TRACE_EVENT(gup_fixup_user_fault, > >> + > >> + TP_PROTO(struct task_struct *tsk, struct mm_struct *mm, > >> + unsigned long address, unsigned int fault_flags), > >> + > >> + TP_ARGS(tsk, mm, address, fault_flags), > >> + > >> + TP_STRUCT__entry( > >> + __array( char, comm, TASK_COMM_LEN ) > > > > Why save the comm? The tracing infrastructure should keep track of that. > > The code is referred to kmem.h which has comm copied. If it is > unnecessary, it definitely could be removed. Sometimes comm isn't that reliable. But really, the only tracepoint that should record it is sched_switch, and sched_wakeup. With those two, the rest of the trace points should be fine. > > > > >> + __field( unsigned long, address ) > >> + ), > >> + > >> + TP_fast_assign( > >> + memcpy(__entry->comm, tsk->comm, TASK_COMM_LEN); > >> + __entry->address = address; > >> + ), > >> + > >> + TP_printk("comm=%s address=%lx", __entry->comm, __entry->address) > >> +); > >> + > >> +TRACE_EVENT(gup_get_user_pages, > >> + > >> + TP_PROTO(struct task_struct *tsk, struct mm_struct *mm, > >> + unsigned long start, unsigned long nr_pages, > >> + unsigned int gup_flags, struct page **pages, > >> + struct vm_area_struct **vmas, int *nonblocking), > >> + > >> + TP_ARGS(tsk, mm, start, nr_pages, gup_flags, pages, vmas, nonblocking), > > > > Why so many arguments? Most are not used. > > My understanding to TP_ARGS may be not right. Doesn't it require all the > args defined by the function? If not, it could definitely be shrunk. > Just need keep the args used by TP_printk? It only needs what is used by TP_fast_assign(). -- 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