From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752662AbcAGTb3 (ORCPT ); Thu, 7 Jan 2016 14:31:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38523 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752015AbcAGTb2 (ORCPT ); Thu, 7 Jan 2016 14:31:28 -0500 Date: Thu, 7 Jan 2016 20:31:25 +0100 From: Jiri Olsa To: "Liang, Kan" Cc: "peterz@infradead.org" , "acme@kernel.org" , "eranian@google.com" , "ak@linux.intel.com" , "jolsa@kernel.org" , "namhyung@kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 1/8] perf: Add PERF_SAMPLE_PHYS_ADDR Message-ID: <20160107193125.GA31607@krava.brq.redhat.com> References: <1452078277-15520-1-git-send-email-kan.liang@intel.com> <20160107083319.GF20434@krava.brq.redhat.com> <37D7C6CF3E00A74B8858931C1DB2F0770586DED0@SHSMSX103.ccr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <37D7C6CF3E00A74B8858931C1DB2F0770586DED0@SHSMSX103.ccr.corp.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 07, 2016 at 03:55:23PM +0000, Liang, Kan wrote: > > > > On Wed, Jan 06, 2016 at 06:04:30AM -0500, kan.liang@intel.com wrote: > > > From: Kan Liang > > > > > > For understanding how the workload maps to memory channels and > > > hardware behavior, it's useful to collect address maps with physical > > addresses. > > > This is not intended for detecting page sharing (which can be already > > > done using the mmap inode), but for lower level hardware behavior > > > studies. > > > Perf supports load latency/DLA which can only collect virtual addresses. > > > This patch add a new sample type PERF_SAMPLE_PHYS_ADDR to expose > > the > > > physical addresses. > > > For kernel direct mapping addresses, the patch uses virt_to_phys to > > > convert the virtual addresses from DLA to physical address. > > > For user virtual addresses, __get_user_pages_fast is used to walk the > > > pages tables for user physical address. > > > This does not work for vmalloc addresses. Right now these are not > > > resolved, but code to do that could be added. > > > For security, the physical address can only be exposed to root or > > > privileged user. > > > > > > Signed-off-by: Kan Liang > > > --- > > > arch/x86/kernel/cpu/perf_event.h | 2 +- > > > arch/x86/kernel/cpu/perf_event_intel_ds.c | 23 > > +++++++++++++++++++++++ > > > include/linux/perf_event.h | 3 +++ > > > include/uapi/linux/perf_event.h | 4 +++- > > > kernel/events/core.c | 11 +++++++++++ > > > 5 files changed, 41 insertions(+), 2 deletions(-) > > > > > > diff --git a/arch/x86/kernel/cpu/perf_event.h > > > b/arch/x86/kernel/cpu/perf_event.h > > > index 799e6bd..164de68 100644 > > > --- a/arch/x86/kernel/cpu/perf_event.h > > > +++ b/arch/x86/kernel/cpu/perf_event.h > > > @@ -90,7 +90,7 @@ struct amd_nb { > > > (PERF_SAMPLE_IP | PERF_SAMPLE_TID | PERF_SAMPLE_ADDR | \ > > > PERF_SAMPLE_ID | PERF_SAMPLE_CPU | > > PERF_SAMPLE_STREAM_ID | \ > > > PERF_SAMPLE_DATA_SRC | PERF_SAMPLE_IDENTIFIER | \ > > > - PERF_SAMPLE_TRANSACTION) > > > + PERF_SAMPLE_TRANSACTION | PERF_SAMPLE_PHYS_ADDR) > > > > could you please add some probe code to detect kernel support, so we get > > some sensible error message > > > > I'm not quite sure what kind of probe code do you mean. > Yes, the error message below is not accurate. It could be some errors in > sample_type, read_format, branch_sample_type or something else. > Because they share the same error code -EINVAL. Perf tool cannot know > more. > I think we may print some error kernel messages when invalid attr is > detected. So the user can get more detail messages from dmesg. > > Or you want me to add some extra code to detect the kernel capability > before opening event? If so, I think we may do it in separate patches. yep, could be done later jirka