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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1731C433F5 for ; Thu, 17 Feb 2022 03:49:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233210AbiBQDt1 (ORCPT ); Wed, 16 Feb 2022 22:49:27 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:45754 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233117AbiBQDtF (ORCPT ); Wed, 16 Feb 2022 22:49:05 -0500 Received: from mail-io1-xd2c.google.com (mail-io1-xd2c.google.com [IPv6:2607:f8b0:4864:20::d2c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ADB7BC5DA4 for ; Wed, 16 Feb 2022 19:48:51 -0800 (PST) Received: by mail-io1-xd2c.google.com with SMTP id a26so2205250iot.6 for ; Wed, 16 Feb 2022 19:48:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=14+i519RyXRhGHkk7y/NizorIrgQMa72y8v5Vs7LOmo=; b=oHx5SA+pA20pWvzGLkJ4yhng4E+IvjuoVEMElPdEpgwBAXZX8Ayc2SvfCLXwvFcehP o0AHme5wuSQ63YxgN3QSc0rUbOV/j/+6G6zQRS4NCVt/yEL1Crq/uwf9UDEKebgjg//9 QjwYPtTiQ0qXnz1UoGaup0sTfsdK8RdEHeUiQduq7H62ZAi7uIXJLbm6AdTtwuFcGXuD HV1h9OqMqWbRjdNwm8pC+0EWihoDDr44lxgfi0RIrrwF4+9Cz21iiE95YFoJBmglrB4c uqhiYzFY7DXRbPHXJsC8Kzs9wY0qwRswwrK0gBC7Y2uHlx1hH59CcbFMZGDMbalV1nve ffkA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=14+i519RyXRhGHkk7y/NizorIrgQMa72y8v5Vs7LOmo=; b=fgx2EXdO7UwfcUOsRUAVkGAxShYZOhTIqY4knDoYFyV2Xd8YyrTaU19mBR6U/RzRc7 f8Ypxi86UboyqJ1JsRss4HejeEPm+BBG2DJw5tUMLYCaFvcSqq7pU6MfAwOPU2Dbm2M8 Kn3Mh9WHtnyIjTRTqj16pXMXwHv+WUHymBh6v15beAwSy4+N5RY+pMvSzsmXxTAwLHvC hMLu6fNFszkK22yUBTnZI+3M8BvbGeHwNiKkA+P4sNw1KpIIEPefZmtmuYV05nLSnVfE ytYRNh+poWSQkLBM1udu9EW4fwtO3paFlC0C69wnYHpkDG0EYhP5U1cb3Gpy8ps44k72 2XUQ== X-Gm-Message-State: AOAM533Z4P/PSBrNKDJsWfLLDe/PIjbHnosnS9YHpBkdNJwW0oWStvUx oSeoQXVQLKnYSvydxTrNELc= X-Google-Smtp-Source: ABdhPJwQdM+YASo9bZwGxmAll7Ye37UoRGfnFLBMbW70/Q8CqJm3xpdtwTbFefjn4OZb9vDTlUFoSw== X-Received: by 2002:a05:6638:1350:b0:314:7f2a:ab14 with SMTP id u16-20020a056638135000b003147f2aab14mr717303jad.215.1645069731093; Wed, 16 Feb 2022 19:48:51 -0800 (PST) Received: from frodo.hsd1.co.comcast.net ([2601:284:8204:2010::1b19]) by smtp.googlemail.com with ESMTPSA id l16sm1127874ilc.54.2022.02.16.19.48.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Feb 2022 19:48:50 -0800 (PST) From: Jim Cromie To: jbaron@akamai.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org Cc: daniel.vetter@ffwll.ch, seanpaul@chromium.org, robdclark@gmail.com, linux@rasmusvillemoes.dk, joe@perches.com, Jim Cromie Subject: [PATCH 10/13] drm_print: refine drm_debug_enabled for dyndbg+jump-label Date: Wed, 16 Feb 2022 20:48:26 -0700 Message-Id: <20220217034829.64395-11-jim.cromie@gmail.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220217034829.64395-1-jim.cromie@gmail.com> References: <20220217034829.64395-1-jim.cromie@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In order to use dynamic-debug's jump-label optimization in drm-debug, its clarifying to refine drm_debug_enabled into 3 uses: 1. drm_debug_enabled - legacy, public 2. __drm_debug_enabled - optimized for dyndbg jump-label enablement. 3. _drm_debug_enabled - pr_debug instrumented, observable 1. The legacy version always checks the bits. 2. is privileged, for use by __drm_dbg(), __drm_dev_dbg(), which do an early return unless the category is enabled (free of call/NOOP side effects). For dyndbg builds, debug callsites are selectively "pre-enabled", so __drm_debug_enabled() short-circuits to true there. Remaining callers of 1 may be able to use 2, case by case. 3. is 1st wrapped in a macro, with a pr_debug, which reports each usage in /proc/dynamic_debug/control, making it observable in the logs. The macro lets the pr_debug see the real caller, not an inline function. When plugged into 1, it identified ~10 remaining callers of the function, leading to the follow-on cleanup patch, and would allow activating the pr_debugs, estimating the callrate, and the potential savings by using the wrapper macro. It is unused ATM, but it fills out the picture. Signed-off-by: Jim Cromie --- drivers/gpu/drm/drm_print.c | 4 ++-- include/drm/drm_print.h | 28 ++++++++++++++++++++++++++++ 2 files changed, 30 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c index e45ba224e57c..92e6e18026da 100644 --- a/drivers/gpu/drm/drm_print.c +++ b/drivers/gpu/drm/drm_print.c @@ -262,7 +262,7 @@ void __drm_dev_dbg(const struct device *dev, enum drm_debug_category category, struct va_format vaf; va_list args; - if (!drm_debug_enabled(category)) + if (!__drm_debug_enabled(category)) return; va_start(args, format); @@ -285,7 +285,7 @@ void ___drm_dbg(enum drm_debug_category category, const char *format, ...) struct va_format vaf; va_list args; - if (!drm_debug_enabled(category)) + if (!__drm_debug_enabled(category)) return; va_start(args, format); diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h index 06f0ee06be1f..38ef044d786e 100644 --- a/include/drm/drm_print.h +++ b/include/drm/drm_print.h @@ -319,11 +319,39 @@ enum drm_debug_category { DRM_UT_DRMRES }; +/* + * 3 name flavors of drm_debug_enabled: + * drm_debug_enabled - public/legacy, always checks bits + * _drm_debug_enabled - instrumented to observe call-rates, est overheads. + * __drm_debug_enabled - privileged - knows jump-label state, can short-circuit + */ static inline bool drm_debug_enabled(enum drm_debug_category category) { return unlikely(__drm_debug & BIT(category)); } +/* + * Wrap fn in macro, so that the pr_debug sees the actual caller, not + * the inline fn. Using this name creates a callsite entry / control + * point in /proc/dynamic_debug/control. + */ +#define _drm_debug_enabled(category) \ + ({ \ + pr_debug("todo: maybe avoid via dyndbg\n"); \ + drm_debug_enabled(category); \ + }) + +#if defined(CONFIG_DRM_USE_DYNAMIC_DEBUG) +/* + * dyndbg is wrapping the drm.debug API, so as to avoid the runtime + * bit-test overheads of drm_debug_enabled() in those api calls. + * In this case, executed callsites are known enabled, so true. + */ +#define __drm_debug_enabled(category) true +#else +#define __drm_debug_enabled(category) drm_debug_enabled(category) +#endif + /* * struct device based logging * -- 2.35.1