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[209.132.180.67]) by mx.google.com with ESMTP id f35si1386621plh.399.2018.12.13.04.43.17; Thu, 13 Dec 2018 04:43:32 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b="hN9M4/oQ"; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729254AbeLMMl6 (ORCPT + 99 others); Thu, 13 Dec 2018 07:41:58 -0500 Received: from mail.kernel.org ([198.145.29.99]:57468 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729115AbeLMMl6 (ORCPT ); Thu, 13 Dec 2018 07:41:58 -0500 Received: from quaco.ghostprotocols.net (unknown [190.15.121.82]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D70932086D; Thu, 13 Dec 2018 12:41:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544704917; bh=X6/laEwHkioF+G7AUlizJqCkKKFXXyzX74qJHQWy8bc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hN9M4/oQRB9t0l6ah3y9UXyUt6u+bRaQy+NvvqzetzQUbDRbgr6CzsH1zw8I1HyiN 4yFwFC6l8Cs0gI49RDWu6mJT3MuCQxHo7HnjxmnuWR4sJ6QL2VLWQ8W3f6gGe/me6W kEid+q1ujxyvkqL8mEaMU74X2qU68FLZen6C0gPI= Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id BC88341B1D; Thu, 13 Dec 2018 09:41:54 -0300 (-03) Date: Thu, 13 Dec 2018 09:41:54 -0300 From: Arnaldo Carvalho de Melo To: Leo Yan Cc: Mathieu Poirier , Alexander Shishkin , Jiri Olsa , Namhyung Kim , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Coresight ML , Mike Leach , Robert Walker Subject: Re: [PATCH v3 6/8] perf cs-etm: Treat NO_SYNC element as trace discontinuity Message-ID: <20181213124154.GF21027@kernel.org> References: <1544513908-16805-1-git-send-email-leo.yan@linaro.org> <1544513908-16805-7-git-send-email-leo.yan@linaro.org> <20181213123854.GE21027@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181213123854.GE21027@kernel.org> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Thu, Dec 13, 2018 at 09:38:54AM -0300, Arnaldo Carvalho de Melo escreveu: > Em Tue, Dec 11, 2018 at 03:38:26PM +0800, Leo Yan escreveu: > > CoreSight tracer driver might insert barrier packet between different > > buffers, thus the decoder can spot the boundaries based on the barrier > > packet; the decoder is possible to hit a barrier packet and emit a > > NO_SYNC element, then the decoder will find a periodic synchronisation > > point inside that next trace block that starts trace again but does not > > have the TRACE_ON element as indicator - usually because this block of > > trace has wrapped the buffer so we have lost the original point that > > trace was enabled. > > > > In upper case, it results in the trace stream only inserts the > > OCSD_GEN_TRC_ELEM_NO_SYNC element in the middle of tracing stream, but > > we don't handle NO_SYNC element properly and at the end users miss to > > see the info for trace discontinuity. > > > "In upper case"? Maybe: > > In the former case it causes the insertion of a OCSD_GEN_TRC_ELEM_NO_SYNC > in the middle of the the tracing stream, but as we were npt handling the > NO_SYNC element properly which ends up making users miss the > discontinuity indication"? > > Though OCSD_GEN_TRC_ELEM_NO_SYNC is different from CS_ETM_TRACE_ON when > > output from the decoder, but both of them indicate the trace data is > > can we remove the "but" and "of them" (redundant) above? > > > discontinuous; this patch treats OCSD_GEN_TRC_ELEM_NO_SYNC as trace > a > > discontinuity and generates CS_ETM_DISCONTINUITY packet for it, so > > cs-etm can handle discontinuity for this case, finally it saves the last > it (way too many "discontinuity") > > trace data for previous trace block and restart samples for new block. I've tentatively done those changes (and a few more) in my local branch, resulting in the wording below, plese let me know if you are ok with it: commit 148068b45fe2e93b19c06cfc1140ea12ca72eb59 Author: Leo Yan Date: Tue Dec 11 15:38:26 2018 +0800 perf cs-etm: Treat NO_SYNC element as trace discontinuity The CoreSight tracer driver might insert a barrier packets between different buffers, thus the decoder can spot the boundaries based on the barrier packet; it is possible for the decoder to hit a barrier packet and emit a NO_SYNC element, then the decoder will find a periodic synchronisation point inside that next trace block that starts the trace again but does not have the TRACE_ON element as indicator - usually because this trace block has wrapped the buffer so we have lost the original point when the trace was enabled. In the first case it causes the insertion of a OCSD_GEN_TRC_ELEM_NO_SYNC in the middle of the the tracing stream, but as we were npt handling the NO_SYNC element properly which ends up making users miss the discontinuity indication"? Though OCSD_GEN_TRC_ELEM_NO_SYNC is different from CS_ETM_TRACE_ON when output from the decoder, both indicate that the trace data is discontinuous; this patch treats OCSD_GEN_TRC_ELEM_NO_SYNC as a trace discontinuity and generates a CS_ETM_DISCONTINUITY packet for it, so cs-etm can handle the discontinuity for this case, finally it saves the last trace data for the previous trace block and restart samples for the new block. Signed-off-by: Leo Yan Reviewed-by: Mathieu Poirier Cc: Alexander Shishkin Cc: Jiri Olsa Cc: Mike Leach Cc: Namhyung Kim Cc: Robert Walker Cc: coresight ml Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1544513908-16805-7-git-send-email-leo.yan@linaro.org Signed-off-by: Arnaldo Carvalho de Melo diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c index 1039f364f4cc..bee026e76a4c 100644 --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c @@ -410,7 +410,6 @@ static ocsd_datapath_resp_t cs_etm_decoder__gen_trace_elem_printer( case OCSD_GEN_TRC_ELEM_UNKNOWN: break; case OCSD_GEN_TRC_ELEM_NO_SYNC: - break; case OCSD_GEN_TRC_ELEM_TRACE_ON: resp = cs_etm_decoder__buffer_discontinuity(decoder, trace_chan_id);