From owner-svn-src-all@FreeBSD.ORG Fri Nov 28 19:21:47 2014 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id CC46F775; Fri, 28 Nov 2014 19:21:47 +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 9DF19906; Fri, 28 Nov 2014 19:21:47 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.9/8.14.9) with ESMTP id sASJLli2079728; Fri, 28 Nov 2014 19:21:47 GMT (envelope-from hselasky@FreeBSD.org) Received: (from hselasky@localhost) by svn.freebsd.org (8.14.9/8.14.9/Submit) id sASJLlcC079727; Fri, 28 Nov 2014 19:21:47 GMT (envelope-from hselasky@FreeBSD.org) Message-Id: <201411281921.sASJLlcC079727@svn.freebsd.org> X-Authentication-Warning: svn.freebsd.org: hselasky set sender to hselasky@FreeBSD.org using -f From: Hans Petter Selasky Date: Fri, 28 Nov 2014 19:21:47 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r275212 - stable/10/sys/kern X-SVN-Group: stable-10 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: Fri, 28 Nov 2014 19:21:47 -0000 Author: hselasky Date: Fri Nov 28 19:21:46 2014 New Revision: 275212 URL: https://svnweb.freebsd.org/changeset/base/275212 Log: MFC r274017, r274088 and r275205: Provide an on-stack temporary buffer for small IOCTL requests. Avoiding a memory allocation per IOCTL request can give a significant speedup for applications which heavily rely on IOCTLs. Modified: stable/10/sys/kern/sys_generic.c Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/kern/sys_generic.c ============================================================================== --- stable/10/sys/kern/sys_generic.c Fri Nov 28 14:51:49 2014 (r275211) +++ stable/10/sys/kern/sys_generic.c Fri Nov 28 19:21:46 2014 (r275212) @@ -75,6 +75,20 @@ __FBSDID("$FreeBSD$"); #include +/* + * The following macro defines how many bytes will be allocated from + * the stack instead of memory allocated when passing the IOCTL data + * structures from userspace and to the kernel. Some IOCTLs having + * small data structures are used very frequently and this small + * buffer on the stack gives a significant speedup improvement for + * those requests. The value of this define should be greater or equal + * to 64 bytes and should also be power of two. The data structure is + * currently hard-aligned to a 8-byte boundary on the stack. This + * should currently be sufficient for all supported platforms. + */ +#define SYS_IOCTL_SMALL_SIZE 128 /* bytes */ +#define SYS_IOCTL_SMALL_ALIGN 8 /* bytes */ + int iosize_max_clamp = 1; SYSCTL_INT(_debug, OID_AUTO, iosize_max_clamp, CTLFLAG_RW, &iosize_max_clamp, 0, "Clamp max i/o size to INT_MAX"); @@ -646,6 +660,7 @@ struct ioctl_args { int sys_ioctl(struct thread *td, struct ioctl_args *uap) { + u_char smalldata[SYS_IOCTL_SMALL_SIZE] __aligned(SYS_IOCTL_SMALL_ALIGN); u_long com; int arg, error; u_int size; @@ -680,17 +695,18 @@ sys_ioctl(struct thread *td, struct ioct arg = (intptr_t)uap->data; data = (void *)&arg; size = 0; - } else - data = malloc((u_long)size, M_IOCTLOPS, M_WAITOK); + } else { + if (size > SYS_IOCTL_SMALL_SIZE) + data = malloc((u_long)size, M_IOCTLOPS, M_WAITOK); + else + data = smalldata; + } } else data = (void *)&uap->data; if (com & IOC_IN) { error = copyin(uap->data, data, (u_int)size); - if (error) { - if (size > 0) - free(data, M_IOCTLOPS); - return (error); - } + if (error != 0) + goto out; } else if (com & IOC_OUT) { /* * Zero the buffer so the user always @@ -704,7 +720,8 @@ sys_ioctl(struct thread *td, struct ioct if (error == 0 && (com & IOC_OUT)) error = copyout(data, uap->data, (u_int)size); - if (size > 0) +out: + if (size > SYS_IOCTL_SMALL_SIZE) free(data, M_IOCTLOPS); return (error); }