From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 88E293B637E for ; Wed, 15 Jul 2026 05:55:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784094928; cv=none; b=FCf9NZLLBstbB8t9ta6OKeRX6oIXufDIlj5W7zmOHhuI9UeSVmAGMwbAz/bpJ2g61WGAnGX+gHwrmSr/oL6kPkL5Zstq02UOmuQnkx26acKijZLyTNl5dWARtRxx5rVHzYT1SI3NmwxgKr/PSwe6EybBkRAVhq2ZIZgDA2w4rog= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784094928; c=relaxed/simple; bh=9wOoehWyBty84/NYlIaqNVsMY8VpGbBjHeJgf6gJJqM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=KEeW4HCOiLr6712A/U0/fmhmlJBQv89btystiyZEpzf+yLvGLo6RFFFu/S9M1WhcbbzxAA3vHveBc6qRZ8NJ74nmUoEk6JD8i1UjZIqmqXYosNqnybti6awdCrza53239fg4f5tOVwehuwXAn8XwuZV5BrjrzJvIMCBvLsKhpiE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xJxG6Q2N; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="xJxG6Q2N" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4B6761F000E9; Wed, 15 Jul 2026 05:55:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784094923; bh=O2RrpCkmY9cKqkAshCQle18YVl4zq7h8lTIgPeTpUTo=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=xJxG6Q2NGrKyvcTpi8Fy/YxQbgJUr/8oQA9YKUZrK7hcG3fkvqY5/WKWHgEM3yymL arlUNiJKyiMTeyLwrZHps2ycp15//MSqx11Apmc7r5uPGueVSM1wZE7e0IhdGh/J55 ZGq72bWLR7Aw6so7rTloLz7AoLwLPDP71caurHFY= Date: Wed, 15 Jul 2026 07:55:17 +0200 From: Greg KH To: "trieu2.huynh" Cc: arve@android.com, tkjos@android.com, brauner@kernel.org, cmllamas@google.com, aliceryhl@google.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] drivers: android: binder: implement CTABS heuristic Message-ID: <2026071500-smooth-cross-fd3a@gregkh> References: <20260714183553.39773-1-trieu2.huynh@lge.corp-partner.google.com> <20260714183553.39773-2-trieu2.huynh@lge.corp-partner.google.com> 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=us-ascii Content-Disposition: inline In-Reply-To: <20260714183553.39773-2-trieu2.huynh@lge.corp-partner.google.com> On Wed, Jul 15, 2026 at 03:35:51AM +0900, trieu2.huynh wrote: > Introduce Cluster/Topology-Aware Binder Selection (CTABS) to optimize > IPC transaction dispatching. > > On asymmetric multi-cluster ARM64 architectures (e.g., big.LITTLE), the > default binder thread selection algorithm is topology-blind. This leads > to frequent cross-cluster thread wakeups, resulting in severe CPU cache > misses, interconnect bottlenecks, and unnecessary cache ping-pongs. > > To mitigate this latency penalty, CTABS evaluates idle waiting threads > based on their last-executed CPU ID and prioritizing them as follows: > > (*) Immediate Selection: Favors threads whose last-executed CPU matches > the caller's CPU exactly, exiting the selection loop early to ensure > optimal L1/L2 cache locality. > (*) Cluster Match: Selects threads that ran on the same CPU cluster as > the caller, maximizing local cache reuse. > (*) Cross-Cluster: Falls back to any available thread across different > clusters if no local affinity is found. > > This topology prioritization maximizes CPU cache reuse, minimizes inter- > cluster snooping overhead, and significantly reduces overall transaction > turnaround latency on modern multi-cluster SoCs. > > Signed-off-by: trieu2.huynh We need a real name here, and a real email address, not a partner.google.com one. thanks, greg k-h