Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752743AbbGNBHE (ORCPT ); Mon, 13 Jul 2015 21:07:04 -0400 Received: from mail-pa0-f54.google.com ([209.85.220.54]:35197 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751741AbbGNBHC (ORCPT ); Mon, 13 Jul 2015 21:07:02 -0400 Date: Tue, 14 Jul 2015 10:04:49 +0900 From: Namhyung Kim To: "Liang, Kan" Cc: "acme@kernel.org" , "jolsa@kernel.org" , "ak@linux.intel.com" , "linux-kernel@vger.kernel.org" , "Hunter, Adrian" Subject: Re: [PATCH RFC V3 3/5] perf,tool: partial time support Message-ID: <20150714010449.GB16880@danjae.kornet> References: <1436345097-11113-1-git-send-email-kan.liang@intel.com> <1436345097-11113-4-git-send-email-kan.liang@intel.com> <20150713132742.GA9917@danjae.kornet> <37D7C6CF3E00A74B8858931C1DB2F0770188BEF4@SHSMSX103.ccr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <37D7C6CF3E00A74B8858931C1DB2F0770188BEF4@SHSMSX103.ccr.corp.intel.com> User-Agent: Mutt/1.5.23+89 (0255b37be491) (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1833 Lines: 43 On Mon, Jul 13, 2015 at 07:01:51PM +0000, Liang, Kan wrote: > > On Wed, Jul 08, 2015 at 04:44:55AM -0400, kan.liang@intel.com wrote: > > > From: Kan Liang > > > > > > When multiple events are sampled it may not be needed to collect fine > > > grained time stamps on all events. The sample sites are usually nearby. > > > It's enough to have time stamps on the regular reference events. > > > This patchkit adds the ability to turn off time stamps per event. This > > > in term can reduce sampling overhead and the size of the perf.data. > > > > So this patch makes the PERF_SAMPLE_TIME bit set or not independently, > > right? But AFAIK we sometimes just use first evsel for checking > > sample_type value, especially for evlist->id_pos. I'm not sure it'll work for > > all cases of mixed time/notime events.. > > > > If the sample_type is different, IDENTIFIER will be set to make sure id is in > a fixed position. So we don't need to worry about evlist->id_pos here. > > I think the only unsupported case should be that the kernel doesn't > support IDENTIFIER. If so, under my test, perf record will print warning > " failed to process type". Perf report will also print warning > " non matching sample_type". So the user can switch back to full time > support. Ah, ok then. > If you think the warning is not good enough, we can show specific > warning and error out when non IDENTIFIER support is detected. Well, I think it's good enough. :) However, perf_evlist__id_hdr_size() seems to be affected also. Are you sure it's okay too? Thanks, Namhyung -- 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/