Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756363AbYHYLlf (ORCPT ); Mon, 25 Aug 2008 07:41:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756122AbYHYLlX (ORCPT ); Mon, 25 Aug 2008 07:41:23 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:47992 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753530AbYHYLlW (ORCPT ); Mon, 25 Aug 2008 07:41:22 -0400 Subject: Re: Quad core CPUs loaded at only 50% when running a CPU and mmap intensive multi-threaded task From: Peter Zijlstra To: edwin Cc: Ingo Molnar , rml@tech9.net, Linux Kernel , "Thomas Gleixner mingo@redhat.com" , "H. Peter Anvin" In-Reply-To: <48B290E7.4070805@gmail.com> References: <48B1CC15.2040006@gmail.com> <1219643476.20732.1.camel@twins> <48B25988.8040302@gmail.com> <1219656190.8515.7.camel@twins> <48B28015.3040602@gmail.com> <1219658527.8515.16.camel@twins> <48B287D8.1000000@gmail.com> <1219660582.8515.24.camel@twins> <48B290E7.4070805@gmail.com> Content-Type: text/plain Date: Mon, 25 Aug 2008 13:41:17 +0200 Message-Id: <1219664477.8515.54.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 600 Lines: 16 On Mon, 2008-08-25 at 14:00 +0300, edwin wrote: > Peter Zijlstra wrote: > > Right - does it make sense to teach clamav about pread() ? > > If it is preferred over mmap, then maybe yes. I would certainly consider this for small (< 1M?) files. With mmap the faults and pte overhead aren't free either, and the extra memcpy from pread() isn't that much. -- 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/