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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 9D977CF537D for ; Wed, 23 Oct 2024 12:53:56 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id CFDE510E7CE; Wed, 23 Oct 2024 12:53:53 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="f5SWrEH2"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.11]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3500310E7CC; Wed, 23 Oct 2024 12:53:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1729688032; x=1761224032; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=s/ijLkvgmNSIDW3lP3xx7kywtJiOOd1nWwIXo6qDPpU=; b=f5SWrEH2Y1Y3XwqBtWiKZSo9ksjH17JI0pYI+uHHmDXzbAyWhUpDX69P JyIIHvuOC/Ov+N6P/h/FvroRcUGupCre4qNmhBcmJOcdG1XFoSAPcD+fO Iy/tOmnDTlxmiyOSCW0p307xJMG7ZFC2UqfD0Y5UR7W7b2SNW7gfXFMh1 Ndi6KIRSp6xGkMk0vDC94ULfu+LXVkecjWsKwvTmpQ3K3SHE6TCafOl4k 2mbGyFIMRrE6XZLu5XomGdT/U/vf42BAgibqoI7yviLdtQeMgM7WGaw2S RyOhEwtOqkP08Ldd5XOn01vHt7aysEas/Lay0UNbMs45U7IdYwbvqqBjk g==; X-CSE-ConnectionGUID: MasKS5S+S6aDQMDa9riWzg== X-CSE-MsgGUID: 7spdOK+mSuy2gwmfzr9dwQ== X-IronPort-AV: E=McAfee;i="6700,10204,11222"; a="39820796" X-IronPort-AV: E=Sophos;i="6.11,199,1725346800"; d="scan'208";a="39820796" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by orvoesa103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Oct 2024 05:53:52 -0700 X-CSE-ConnectionGUID: FTXxJjn7SVSm7c7cxdb7qg== X-CSE-MsgGUID: 3LglOoHNTba2rgHa1ro+ZA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.11,226,1725346800"; d="scan'208";a="79859858" Received: from kniemiec-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.246.84]) by fmviesa007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Oct 2024 05:53:48 -0700 From: Jani Nikula To: Uros Bizjak , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Cc: Uros Bizjak , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Simona Vetter Subject: Re: [PATCH] drm/i915/active: Use try_cmpxchg() in active_fence_cb() In-Reply-To: <20241003084533.871524-1-ubizjak@gmail.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20241003084533.871524-1-ubizjak@gmail.com> Date: Wed, 23 Oct 2024 15:53:46 +0300 Message-ID: <87ttd3t1yd.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Thu, 03 Oct 2024, Uros Bizjak wrote: > Replace this pattern in active_fence_cb(): > > cmpxchg(*ptr, old, new) == old > > ... with the simpler and faster: > > try_cmpxchg(*ptr, &old, new) > > The x86 CMPXCHG instruction returns success in the ZF flag, > so this change saves a compare after the CMPXCHG. > > Signed-off-by: Uros Bizjak > Cc: Jani Nikula > Cc: Joonas Lahtinen > Cc: Rodrigo Vivi > Cc: Tvrtko Ursulin > Cc: David Airlie > Cc: Simona Vetter Pushed to drm-intel-next, thanks for the patch. BR, Jani. > --- > drivers/gpu/drm/i915/i915_active.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c > index 5ec293011d99..35319228bc51 100644 > --- a/drivers/gpu/drm/i915/i915_active.c > +++ b/drivers/gpu/drm/i915/i915_active.c > @@ -212,7 +212,7 @@ active_fence_cb(struct dma_fence *fence, struct dma_fence_cb *cb) > struct i915_active_fence *active = > container_of(cb, typeof(*active), cb); > > - return cmpxchg(__active_fence_slot(active), fence, NULL) == fence; > + return try_cmpxchg(__active_fence_slot(active), &fence, NULL); > } > > static void -- Jani Nikula, Intel