Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754280Ab2EXJEB (ORCPT ); Thu, 24 May 2012 05:04:01 -0400 Received: from mga01.intel.com ([192.55.52.88]:29478 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752391Ab2EXJD7 (ORCPT ); Thu, 24 May 2012 05:03:59 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="170774395" Message-ID: <4FBDF91C.7050902@intel.com> Date: Thu, 24 May 2012 17:02:20 +0800 From: Alex Shi User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:9.0) Gecko/20111229 Thunderbird/9.0 MIME-Version: 1.0 To: Jan Beulich CC: borislav.petkov@amd.com, arnd@arndb.de, Peter Zijlstra , akinobu.mita@gmail.com, eric.dumazet@gmail.com, fweisbec@gmail.com, rostedt@goodmis.org, hughd@google.com, jeremy@goop.org, len.brown@intel.com, tony.luck@intel.com, yongjie.ren@intel.com, kamezawa.hiroyu@jp.fujitsu.com, seto.hidetoshi@jp.fujitsu.com, penberg@kernel.org, yinghai@kernel.org, tglx@linutronix.de, akpm@linux-foundation.org, ak@linux.intel.com, luto@mit.edu, avi@redhat.com, dhowells@redhat.com, mingo@redhat.com, riel@redhat.com, cpw@sgi.com, steiner@sgi.com, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, hpa@zytor.com Subject: Re: [PATCH v7 8/8] x86/tlb: just do tlb flush on one of siblings of SMT References: <1337782555-8088-1-git-send-email-alex.shi@intel.com> <1337782555-8088-9-git-send-email-alex.shi@intel.com> <4FBD18D20200007800085951@nat28.tlf.novell.com> <1337792984.9783.37.camel@laptop> <4FBDF200.7060608@intel.com> <4FBE11EB0200007800085BD0@nat28.tlf.novell.com> In-Reply-To: <4FBE11EB0200007800085BD0@nat28.tlf.novell.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1010 Lines: 33 >> >> I just measured the cost of this function on my Romely EP(32 LCPUs) with >> cpumask_t and NR_CPUS = 32/256/512/4096, the cost are similar with >> 256/512/4096 and that increased about 20% time cost from 32. >> >> I also tried to use cpumask_var_t and alloc it in heap(use >> CPUMASK_OFFSTACK), actually, it cost same time with cpumask_t in stack. >> But, the allocation bring another big cost. So, I use cpumask_t in stack. >> The performance gain data in commit log is getting with NR_CPUS = 256. > > Perhaps using a per-CPU cpumask would be the better choice here See. > (I can't see how preemption could validly be enabled when this > code is utilized). Sorry, What's your meaning here?, the function is always in pre-empt safe mode. > > Jan > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/