From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 23 Dec 2002 08:33:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 23 Dec 2002 08:33:49 -0500 Received: from e6.ny.us.ibm.com ([32.97.182.106]:31366 "EHLO e6.ny.us.ibm.com") by vger.kernel.org with ESMTP id ; Mon, 23 Dec 2002 08:33:48 -0500 Date: Mon, 23 Dec 2002 19:08:48 +0530 From: Ravikiran G Thirumalai To: "David S. Miller " Cc: netdev , linux-kernel@vger.kernel.org Subject: [patch] Convert sockets_in_use to use per_cpu areas Message-ID: <20021223190847.G23413@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, Here's a simple patch to change sockets_in_use to make use of per-cpu areas. I have couple of questions though... 1. Was this var made per-cpu just to avoid atomic_t or locking or are there real life workloads which cause too many sock_alloc and sock_releases to cause cacheline bouncing? 2. Is this var required? since we can just sum up all proto->stats.inuse and remove this var altogether? (This var is read only for /proc reporting) Thanks, Kiran diff -ruN -X dontdiff linux-2.5.52/net/socket.c sockets_in_use-2.5.52/net/socket.c --- linux-2.5.52/net/socket.c Mon Dec 16 07:37:53 2002 +++ sockets_in_use-2.5.52/net/socket.c Mon Dec 23 11:48:44 2002 @@ -189,10 +189,7 @@ * Statistics counters of the socket lists */ -static union { - int counter; - char __pad[SMP_CACHE_BYTES]; -} sockets_in_use[NR_CPUS] __cacheline_aligned = {{0}}; +static DEFINE_PER_CPU(int, sockets_in_use); /* * Support routines. Move socket addresses back and forth across the kernel/user @@ -475,7 +472,8 @@ inode->i_uid = current->fsuid; inode->i_gid = current->fsgid; - sockets_in_use[smp_processor_id()].counter++; + get_cpu_var(sockets_in_use)++; + put_cpu_var(sockets_in_use); return sock; } @@ -511,7 +509,8 @@ if (sock->fasync_list) printk(KERN_ERR "sock_release: fasync list not empty!\n"); - sockets_in_use[smp_processor_id()].counter--; + get_cpu_var(sockets_in_use)--; + put_cpu_var(sockets_in_use); if (!sock->file) { iput(SOCK_INODE(sock)); return; @@ -1851,7 +1850,7 @@ int counter = 0; for (cpu = 0; cpu < NR_CPUS; cpu++) - counter += sockets_in_use[cpu].counter; + counter += per_cpu(sockets_in_use, cpu); /* It can be negative, by the way. 8) */ if (counter < 0)