From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A00E7331EBA for ; Sat, 26 Sep 2026 22:33:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790462034; cv=none; b=XneTI5VrPyKlp5tGdzMQmJxVOxBik2yjLVWnxgrX1D0Ex98S02zNWZ0lKZ824adVanZfxlGrx9Wm1ZF51pvItXVO+zLFpNIePvfZ0YEyR068onsztfhmiMkh+MBipyhFw9ReTGckxRvON1rwFh/+lor4YP40jzHag5bO9DwASMc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790462034; c=relaxed/simple; bh=5EjlbXzfNhhj2rFbPScAbyukxVXncWxCqZbBtLgd2Gc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=eZviTUTlvZeSRgiia4rM5doDevS8RzvTbx6Bck24Q5QjWJMghkrzDsF0RIJVeRmXxNCp0QC7x31XrNHbDCoU48BXDpFeqpZbF4pXidHTueb7C0ZuxA1Z6/kBAXvKw1pudQZxg5Q6YaSc/UNUJJ2pREeJxvrn4nUyYg1zPch+jFw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LskNpArg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LskNpArg" Received: by smtp.kernel.org (Postfix) with ESMTPS id 3C0B4C2BCC7; Sat, 26 Sep 2026 22:33:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1790462034; bh=5EjlbXzfNhhj2rFbPScAbyukxVXncWxCqZbBtLgd2Gc=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=LskNpArgBG/fYyfbkpDz2jDlqGHlCqQJ3QyIitRdBdxlgFIU46X+bw6Yx5YKf3bQE UEv348aKBPLKLiZpISVoqJeIwoTRNIAQ4XK4hyTlfGaheV1/M9ewui4UDuQS6i6h97 t841JEaxFuJ4g8oDIzg6awRPCT5Yx3ZuWE63LT6zAjY3Wr18WCuH/gBR8uYoj0LvPh /2WKdgz/B7yNqoOgfRQceM6GD5FQHMEJE/PIIhNC6nMUV0SYPW7NGywVdLE4AxrUZJ sypKQhP9urJsFQmmRBz66QqbTnjHTl1cLLa3T6pZ8RYgTJwCXTY5HP/sfbK8RGchlu bBgi2EJv8Huyw== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1C439C9832A; Sat, 26 Sep 2026 22:33:54 +0000 (UTC) From: Jim Cromie via B4 Relay Date: Sat, 26 Sep 2026 16:33:32 -0600 Subject: [PATCH 1/2] drm/print: Mark __drm_debug as __read_mostly Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260926-rd-mostly-v1-1-28b7d714ed2c@gmail.com> References: <20260926-rd-mostly-v1-0-28b7d714ed2c@gmail.com> In-Reply-To: <20260926-rd-mostly-v1-0-28b7d714ed2c@gmail.com> To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Jim Cromie X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1790462033; l=1186; i=jim.cromie@gmail.com; s=20260203; h=from:subject:message-id; bh=NHYPZMcwo+bZTlMUWxR3C+eUOnJQOrGzS6sFjK6QR7o=; b=SCaWekTeF5fI3x8YyVSdoR1Ax7xSj1vUuUes5O/Lc6T011ZE8poxxwKWNHG6UFxmCcbVFIVLu XmfS+0EWTuNCmaFvvUO6vSgKQVVUBQmiYxmh1hytdPG4sKn4VpuvFIR X-Developer-Key: i=jim.cromie@gmail.com; a=ed25519; pk=C6E5ODlPQo7ZBynATXH9wg7K6HxP0pIXyf4s38Qw0XE= X-Endpoint-Received: by B4 Relay for jim.cromie@gmail.com/20260203 with auth_id=958 X-Original-From: Jim Cromie Reply-To: jim.cromie@gmail.com From: Jim Cromie Under a multi-client workload of 12 concurrent vkcubes on AMD iGPU, __drm_debug is read at ~83.3 kHz across multiple cores during atomic and vblank checks. __drm_debug is written only when userspace does: echo 0xff > /sys/module/drm/parameters/debug Currently the linker packs __drm_debug into .bss adjacent to hot structures: drm_lease_idr_object, drm_class, and drm_global_mutex, causing unnecessary cacheline invalidations. Mark __drm_debug as __read_mostly to relocate it to .data..read_mostly. Signed-off-by: Jim Cromie --- drivers/gpu/drm/drm_print.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c index 86cef1a37678..50cdeb1b15e2 100644 --- a/drivers/gpu/drm/drm_print.c +++ b/drivers/gpu/drm/drm_print.c @@ -40,7 +40,7 @@ * __drm_debug: Enable debug output. * Bitmask of DRM_UT_x. See include/drm/drm_print.h for details. */ -unsigned long __drm_debug; +unsigned long __drm_debug __read_mostly; EXPORT_SYMBOL(__drm_debug); MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug category.\n" -- 2.55.0