From patchwork Mon May 16 22:56:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jim Cromie X-Patchwork-Id: 12851597 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 02497C43217 for ; Mon, 16 May 2022 22:57:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350105AbiEPW5y (ORCPT ); Mon, 16 May 2022 18:57:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350032AbiEPW5a (ORCPT ); Mon, 16 May 2022 18:57:30 -0400 Received: from mail-il1-x135.google.com (mail-il1-x135.google.com [IPv6:2607:f8b0:4864:20::135]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F4EC4664B; Mon, 16 May 2022 15:57:26 -0700 (PDT) Received: by mail-il1-x135.google.com with SMTP id e4so2302460ils.12; Mon, 16 May 2022 15:57:26 -0700 (PDT) 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=it6bLhFwPCS9KNMNbVAc9u0r1hyTQEpcTOU7DVjaIzc=; b=cLcNGP066hHaVqlFNtXCmZ1CGCDAlRmjr8Ddi2wGeCAS0G188epVjNoMgFTsYz1FhS KwC/fi5w0MCKcVhAzgWTaAyw+jbVNB24fPtZqpyM2QJFQ425pkWWyCI9IkbK/sjrV1Nr VH0wWrWNzvvR6xEjBnwkVSgs88cMc3hP8dkgdaIQ1LrtD/VWN/UO2s3FRnPa5oMd5so8 fSnTqRZENTyoMjCDNvkBUwdEdImN8cxny/1EuyBgylEspCk+qlkkMhhF7mjiK7FL010n kgcvXTfvTotxDueX1P4iF6MOjOgVE7J7E3ZeBWAm2Cih8qFLTTugQGWmxTynuy+uGziA gtrg== 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=it6bLhFwPCS9KNMNbVAc9u0r1hyTQEpcTOU7DVjaIzc=; b=dFOHme8VL5erZQ2qp59ibzPSqVdwFpmTUBwGuvFlSAFN02CLOMVifg7fb08CxuVAAH Qsbm6/TBr3m4v7ogGc33t+EtdQt9odUPfRiaGgQwuEGQvRiEzN40q9P/GWVexd8UgFiU EBpdlL3iehsZyA0YoSDuKYimqqWbq4BubRH30UAhuJOI/AgPdZb7cGAiPuMMoZ5/jh1l WaTMfFOb67aU23jxAO/TAywKKAcoF/53JKE42a6e9bjVMF+/MO35MHNuftqFRgCxXa25 kLLs3rDYB+s7L04iC5GldJRMQjM9NGvqwh+vR46QFcx6M3NUYGJY067agtMrjrbCyS2R zk6w== X-Gm-Message-State: AOAM530YQhyhzKSz6I/hizRFBs+a480ZvReJOIWYf1hP7fQX3QCUWBUK 1Cm+/JovxEcSpt37Ao88Jok= X-Google-Smtp-Source: ABdhPJxL66r9um/Qj19jzq2i+w5GjaE1kV2BNicea7CTlLXB+S6WjzXBR8GSASV1PB+CpOnfV72D2w== X-Received: by 2002:a05:6e02:1d8a:b0:2cd:fa75:6395 with SMTP id h10-20020a056e021d8a00b002cdfa756395mr10067705ila.294.1652741845777; Mon, 16 May 2022 15:57:25 -0700 (PDT) Received: from frodo.hsd1.co.comcast.net ([2601:284:8204:2010::dd9f]) by smtp.googlemail.com with ESMTPSA id k26-20020a02661a000000b0032b74686763sm3133949jac.76.2022.05.16.15.57.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 May 2022 15:57:25 -0700 (PDT) From: Jim Cromie To: jbaron@akamai.com, 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: gregkh@linuxfoundation.org, daniel.vetter@ffwll.ch, seanpaul@chromium.org, robdclark@gmail.com, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, quic_saipraka@quicinc.com, will@kernel.org, catalin.marinas@arm.com, quic_psodagud@quicinc.com, maz@kernel.org, arnd@arndb.de, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, mingo@redhat.com, jim.cromie@gmail.com Subject: [PATCH v2 20/27] drm_print: refine drm_debug_enabled for jump-label Date: Mon, 16 May 2022 16:56:33 -0600 Message-Id: <20220516225640.3102269-21-jim.cromie@gmail.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220516225640.3102269-1-jim.cromie@gmail.com> References: <20220516225640.3102269-1-jim.cromie@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@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 5192533794a2..22b7ab1c5c40 100644 --- a/drivers/gpu/drm/drm_print.c +++ b/drivers/gpu/drm/drm_print.c @@ -272,7 +272,7 @@ 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); @@ -295,7 +295,7 @@ 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 5c39bacac2b3..ccd177236ab3 100644 --- a/include/drm/drm_print.h +++ b/include/drm/drm_print.h @@ -324,11 +324,39 @@ 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 *