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 X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CDA73C1B0F6 for ; Wed, 20 Jun 2018 08:28:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 871D5208B3 for ; Wed, 20 Jun 2018 08:28:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="drE0uTbS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 871D5208B3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=sai.msu.ru Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754204AbeFTI2k (ORCPT ); Wed, 20 Jun 2018 04:28:40 -0400 Received: from mail-oi0-f65.google.com ([209.85.218.65]:36786 "EHLO mail-oi0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754166AbeFTI2f (ORCPT ); Wed, 20 Jun 2018 04:28:35 -0400 Received: by mail-oi0-f65.google.com with SMTP id 14-v6so2283597oie.3; Wed, 20 Jun 2018 01:28:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=jX28PvL9TrT72W9DrwnvYnb8EKDt6Lt2v35zFF11A54=; b=drE0uTbScU1/dyoHIRp+gf47Jd27x2uALX6MtoXK0Bdqr972eYSBrBrNsT8TinVdgi IANWru8sWCDXMn+I8q9xKorxO7Gadzmp27SHOO5/yR+uyjOP89KtQUHqY+EUzza9JPWq eYto89ndOVnRuFTzeK051byLwBxbgX27XlULrbxKsktTb3fnvaQ/FqhKcNt6/8Y5oD8+ 5RJtsUEmYDwuslj3KwPVc/FbR5mSSWUG8WKTDbq4qLbNvFXuAlHaPM0RV4zQ55BbtCGx F6g6tvRVCLfC25j5i+M77QtCL/RoxiiswUH56epcS1Q/7Qq1guZDGfV5l5jDgsP5EdGu s/sg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=jX28PvL9TrT72W9DrwnvYnb8EKDt6Lt2v35zFF11A54=; b=MMNNSvbV98ByqhvhTqClKRdLObJUVhqSHfYo6Q+9gVzLznYecn1CSEP0u3xYegXHRL y6nzNdBLHh/WmHhCfcsryvPjwXWNZiWirJemwIsG5VaIMdjAwvYXkAmG3MBgD/Atcd4G 7CF8aXR4yIpJIkuPQTSc02XWarV4c8GAtvYkZG63jrqqwQnMCIxp+aBF2m40clry9VM1 qJFJZk2bA5O87QsQF+041Vu9Lf92GeLBHzvHwIy7TAy/WVD/PWfp+YqDN8SY60Hy44yK WHDX9T2u34+Yb/h+08SR8jhqi+HG2eyRYtpIH0+Cl8rZQjR5C+d4Sug8hvJm8xC6bZ7K pj7w== X-Gm-Message-State: APt69E0B2j0b2Fuiq0Rjtpesf4TQAWlZDTITgRNCLifeIPhOmoEtQO4P BpV6SjuPyw7SIdPv1Ixa9xX2eGsIPRe/LxZcRCk= X-Google-Smtp-Source: ADUXVKK5Fu1tZh20zB7ViCHtVGYPoOPWGliyfZfJ6TDtEzysigLUklQmeqN85DCtNQDCatZBSdOiJn/OoH4alKTAv0w= X-Received: by 2002:aca:ea42:: with SMTP id i63-v6mr11836802oih.260.1529481972066; Wed, 20 Jun 2018 01:06:12 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a9d:743:0:0:0:0:0 with HTTP; Wed, 20 Jun 2018 01:05:51 -0700 (PDT) In-Reply-To: <20180619123329.52bf6216@gandalf.local.home> References: <20180617143625.32133-1-matwey@sai.msu.ru> <20180618145854.2092c6e0@gandalf.local.home> <20180619123329.52bf6216@gandalf.local.home> From: "Matwey V. Kornilov" Date: Wed, 20 Jun 2018 11:05:51 +0300 X-Google-Sender-Auth: TAFkSpAve9ji1eUVFPji_TQBt14 Message-ID: Subject: Re: [PATCH 1/2] Add TRACE_EVENTs in pwc_isoc_handler() To: Steven Rostedt Cc: hverkuil@xs4all.nl, mchehab@kernel.org, mingo@redhat.com, Mike Isely , Bhumika Goyal , Colin King , linux-media@vger.kernel.org, open list Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2018-06-19 19:33 GMT+03:00 Steven Rostedt : > On Tue, 19 Jun 2018 19:23:04 +0300 > "Matwey V. Kornilov" wrote: > >> Hi Steven, >> >> Thank you for valuable comments. >> >> This is for measuring performance of URB completion callback inside PWC driver. >> What do you think about moving events to __usb_hcd_giveback_urb() in >> order to make this more generic? Like the following: >> >> local_irq_save(flags); >> // trace urb complete enter >> urb->complete(urb); >> // trace urb complete exit >> local_irq_restore(flags); >> >> > > If that can work for you, I'm fine with that. Trace events may be > cheap, but they do come with some cost. I'd like to have all trace > events be as valuable as possible, and limit the "special case" ones. What is the cost for events? I suppose one conditional check when trace is disabled? There is already similar debugging stuff related to usbmon in __usb_hcd_giveback_urb(), so I don't think that another conditional check will hurt performance dramatically there. When discussing second patch in this series I see that the issue that it is intended to resolve may be common to other USB media drivers. > > -- Steve > -- With best regards, Matwey V. Kornilov. Sternberg Astronomical Institute, Lomonosov Moscow State University, Russia 119234, Moscow, Universitetsky pr-k 13, +7 (495) 9392382