From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 119BBC433EF for ; Fri, 29 Apr 2022 13:31:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:CC:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=UqrqBzjC+7CBCkfwm91Tu6olWJ9RdLgj0dMqsokQd/E=; b=4xLwAAuma9htNr FfkoSiUrltAXeKmd5zC1etcw0qzVt1hLe3yp8/UKWai58huZ6Rhr/7NMDJ6BIDO0RRQiZwH7b3IOZ aYh2iUwqTbWiBOugjOHZQYsV62x//mbgqRzsh3eXyUrnRcFrEpeLOQ3ynEkSDf7CTjwmRqr/lRhYm f3eCcvyeYLJxajIJMJIBMSjeHL5Qs0a4MVsvtOg0TocALesu1L0D5H1h4h00z6R+1eAvXs3/wkXOo 2PzyEde7FQn5BPMilWM1jX75p8OBmklb35Xz3aWe4Wt5FPBQZj1RL7zTabDtcviv3j2CpN0RNVZAM YwsmMmJF/qemS3vKLGYA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nkQhC-00BNE7-EL; Fri, 29 Apr 2022 13:30:06 +0000 Received: from alexa-out.qualcomm.com ([129.46.98.28]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nkQh8-00BNBq-7H for linux-arm-kernel@lists.infradead.org; Fri, 29 Apr 2022 13:30:03 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1651239002; x=1682775002; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=Btlb4CgDcjwJRkvMOtx4nRpvsq3KlJpwPzQzTvO4w5A=; b=APWGSyuLtGDPAvviyngWPHQm+58fFZ2hQzEdvrqqn5VkyF9WVob9Ho5/ w6FH9ZJPKVlmp85T8O5jqOXu8CYLU37t6oGwt48DLzc6aoGHfN+eFnAOL o89sL1PD57/+J4AgONNhivzTA9I79kdmn9+X37xMTUwB7Ub3TVWmgeYPO 4=; Received: from ironmsg-lv-alpha.qualcomm.com ([10.47.202.13]) by alexa-out.qualcomm.com with ESMTP; 29 Apr 2022 06:29:59 -0700 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg-lv-alpha.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Apr 2022 06:29:58 -0700 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Fri, 29 Apr 2022 06:29:58 -0700 Received: from [10.50.11.55] (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Fri, 29 Apr 2022 06:29:52 -0700 Message-ID: <498791a7-cc9c-536a-0859-b03a332dc922@quicinc.com> Date: Fri, 29 Apr 2022 18:59:48 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 Subject: Re: [PATCHv13 9/9] soc: qcom: geni: Disable MMIO tracing for GENI SE Content-Language: en-US To: Steven Rostedt CC: , , , , , , , , , , Bjorn Andersson References: <3b2fb1e02f7a9836b2388b9f2ce2184c5a0cd444.1651149615.git.quic_saipraka@quicinc.com> <20220428092959.175b48ae@gandalf.local.home> From: Sai Prakash Ranjan In-Reply-To: <20220428092959.175b48ae@gandalf.local.home> X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220429_063002_419864_A2D9EDD6 X-CRM114-Status: GOOD ( 17.67 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Steve, On 4/28/2022 6:59 PM, Steven Rostedt wrote: > On Thu, 28 Apr 2022 18:14:12 +0530 > Sai Prakash Ranjan wrote: > >> Disable MMIO tracing for geni serial engine driver as it is a >> high frequency operation with many register reads/writes and >> not very useful to log all MMIO traces and prevent excessive >> logging. > This states what it does but does not really state why. Are you using MMIO > tracing in other locations and this is causing too much noise? > What is the real issue. Just saying "excessive logging" is not sufficient. > That would be a reason to disable function tracing ;-) > > -- Steve > Disabling MMIO trace is what it does and why it does is to prevent excessive logging. I will add more details on why preventing excessive logging is required here. It is quite known that any access over serial console would involve a lot of TX and RX register accesses (and few others), so these MMIO read/write trace events in these drivers cause a lot of unwanted noise because of the high frequency of such operations and is not very useful tracing these events for such driver. And we want to enable these trace events on development devices(maybe not production devices) where performance also really matters since we want to debug and track any crashes with such register accesses on these devices and not just something which runs with every debug option out there (meaning we enable this MMIO tracing with almost on par production kernels). And these traces of such driver add additional overhead both in terms of memory and CPU cycles. And also one more reason is that if we try to display trace buffer containing these register trace events onto serial console, then it would also involve register accesses from these drivers which would lead to recursive tracing. I will update the commit text adding these details and since we got your attention, can you also please look at patch 5 [1] which was updated based on your previous review comments. If you could review/ack them, then Arnd can take this series into his tree once I post the next version with these updated commit text. [1] https://lore.kernel.org/lkml/9827bae40f6f319f294d06859c9e3c7442f067f2.1651149615.git.quic_saipraka@quicinc.com/ Thanks, Sai >> Cc: Bjorn Andersson >> Signed-off-by: Sai Prakash Ranjan >> --- >> drivers/soc/qcom/qcom-geni-se.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/drivers/soc/qcom/qcom-geni-se.c b/drivers/soc/qcom/qcom-geni-se.c >> index 28a8c0dda66c..a0ceeede450f 100644 >> --- a/drivers/soc/qcom/qcom-geni-se.c >> +++ b/drivers/soc/qcom/qcom-geni-se.c >> @@ -1,6 +1,9 @@ >> // SPDX-License-Identifier: GPL-2.0 >> // Copyright (c) 2017-2018, The Linux Foundation. All rights reserved. >> >> +/* Disable MMIO tracing to prevent excessive logging of unwanted MMIO traces */ >> +#define __DISABLE_TRACE_MMIO__ >> + >> #include >> #include >> #include _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel