From owner-svn-src-all@FreeBSD.ORG Tue Nov 4 11:29:50 2014 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 1B7FDF58; Tue, 4 Nov 2014 11:29:50 +0000 (UTC) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 07C31F4B; Tue, 4 Nov 2014 11:29:50 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.9/8.14.9) with ESMTP id sA4BTnnG030601; Tue, 4 Nov 2014 11:29:49 GMT (envelope-from hselasky@FreeBSD.org) Received: (from hselasky@localhost) by svn.freebsd.org (8.14.9/8.14.9/Submit) id sA4BTnwX030600; Tue, 4 Nov 2014 11:29:49 GMT (envelope-from hselasky@FreeBSD.org) Message-Id: <201411041129.sA4BTnwX030600@svn.freebsd.org> X-Authentication-Warning: svn.freebsd.org: hselasky set sender to hselasky@FreeBSD.org using -f From: Hans Petter Selasky Date: Tue, 4 Nov 2014 11:29:49 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r274088 - head/sys/kern X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 04 Nov 2014 11:29:50 -0000 Author: hselasky Date: Tue Nov 4 11:29:49 2014 New Revision: 274088 URL: https://svnweb.freebsd.org/changeset/base/274088 Log: Simplify logic a bit. Ensure data buffer is properly aligned, especially for platforms where unaligned access is not allowed. Make it possible to override the small buffer size. A simple continuous read string test using libusb showed a reduction in CPU usage from roughly 10% to less than 1% using a dual-core GHz CPU, when the malloc() operation was skipped for small buffers. MFC after: 2 weeks Modified: head/sys/kern/sys_generic.c Modified: head/sys/kern/sys_generic.c ============================================================================== --- head/sys/kern/sys_generic.c Tue Nov 4 10:25:52 2014 (r274087) +++ head/sys/kern/sys_generic.c Tue Nov 4 11:29:49 2014 (r274088) @@ -646,10 +646,13 @@ struct ioctl_args { int sys_ioctl(struct thread *td, struct ioctl_args *uap) { +#ifndef SYS_IOCTL_SMALL_SIZE +#define SYS_IOCTL_SMALL_SIZE 128 +#endif + u_char smalldata[SYS_IOCTL_SMALL_SIZE] __aligned(8); u_long com; int arg, error; u_int size; - u_char smalldata[128]; caddr_t data; if (uap->com > 0xffffffff) { @@ -682,10 +685,10 @@ sys_ioctl(struct thread *td, struct ioct data = (void *)&arg; size = 0; } else { - if (size <= sizeof(smalldata)) - data = smalldata; - else + if (size > SYS_IOCTL_SMALL_SIZE) data = malloc((u_long)size, M_IOCTLOPS, M_WAITOK); + else + data = smalldata; } } else data = (void *)&uap->data; @@ -707,7 +710,7 @@ sys_ioctl(struct thread *td, struct ioct error = copyout(data, uap->data, (u_int)size); out: - if (size > 0 && data != (caddr_t)&smalldata) + if (size > SYS_IOCTL_SMALL_SIZE) free(data, M_IOCTLOPS); return (error); }