From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f41.google.com (mail-wm0-f41.google.com [74.125.82.41]) by kanga.kvack.org (Postfix) with ESMTP id 1543E82F82 for ; Thu, 10 Dec 2015 05:03:37 -0500 (EST) Received: by mail-wm0-f41.google.com with SMTP id c201so24672759wme.0 for ; Thu, 10 Dec 2015 02:03:37 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id wz10si17791064wjc.58.2015.12.10.02.03.35 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 10 Dec 2015 02:03:35 -0800 (PST) Subject: Re: [PATCH v2 1/3] mm, printk: introduce new format string for flags References: <87io4hi06n.fsf@rasmusvillemoes.dk> <1449242195-16374-1-git-send-email-vbabka@suse.cz> <20151210025944.GB17967@js1304-P5Q-DELUXE> <20151210040456.GC7814@home.goodmis.org> From: Vlastimil Babka Message-ID: <56694DF6.70600@suse.cz> Date: Thu, 10 Dec 2015 11:03:34 +0100 MIME-Version: 1.0 In-Reply-To: <20151210040456.GC7814@home.goodmis.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Steven Rostedt , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Minchan Kim , Sasha Levin , "Kirill A. Shutemov" , Mel Gorman , Michal Hocko , Rasmus Villemoes On 12/10/2015 05:04 AM, Steven Rostedt wrote: > On Thu, Dec 10, 2015 at 11:59:44AM +0900, Joonsoo Kim wrote: >> Ccing, Steven to ask trace-cmd problem. >> >> I'd like to use %pgp in tracepoint output. It works well when I do >> 'cat /sys/kernel/debug/tracing/trace' but not works well when I do >> './trace-cmd report'. It prints following error log. >> >> [page_ref:page_ref_unfreeze] bad op token & >> [page_ref:page_ref_set] bad op token & >> [page_ref:page_ref_mod_unless] bad op token & >> [page_ref:page_ref_mod_and_test] bad op token & >> [page_ref:page_ref_mod_and_return] bad op token & >> [page_ref:page_ref_mod] bad op token & >> [page_ref:page_ref_freeze] bad op token & >> >> Following is the format I used. >> >> TP_printk("pfn=0x%lx flags=%pgp count=%d mapcount=%d mapping=%p mt=%d val=%d ret=%d", >> __entry->pfn, &__entry->flags, __entry->count, >> __entry->mapcount, __entry->mapping, __entry->mt, >> __entry->val, __entry->ret) >> >> Could it be solved by 'trace-cmd' itself? You mean that trace-cmd/parse-events.c would interpret the raw value of flags by itself? That would mean the flags became fixed ABI, not a good idea... >> Or it's better to pass flags by value? If it's value (as opposed to a pointer in %pgp), that doesn't change much wrt. having to intepret them? >> Or should I use something like show_gfp_flags()? Sounds like least pain to me, at least for now. We just need to have the translation tables available as #define with __print_flags() in some trace/events header, like the existing trace/events/gfpflags.h for gfp flags. These tables can still be reused within mm/debug.c or printk code without copy/paste, like I did in "[PATCH v2 6/9] mm, debug: introduce dump_gfpflag_names() for symbolic printing of gfp_flags" [1]. Maybe it's not the most elegant solution, but works without changing parse-events.c using the existing format export. So if you agree, I can do this in the next spin. [1] https://lkml.org/lkml/2015/11/24/354 > Yes this can be solved in perf and trace-cmd via the parse-events.c file. And > as soon as that happens, whatever method we decide upon becomes a userspace > ABI. So don't think you can change it later. > > -- 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