From owner-svn-src-all@FreeBSD.ORG Sat Nov 29 05:08:30 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 5133C605; Sat, 29 Nov 2014 05:08:30 +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 24B8775A; Sat, 29 Nov 2014 05:08:30 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.9/8.14.9) with ESMTP id sAT58Ubb055495; Sat, 29 Nov 2014 05:08:30 GMT (envelope-from hselasky@FreeBSD.org) Received: (from hselasky@localhost) by svn.freebsd.org (8.14.9/8.14.9/Submit) id sAT58UqA055494; Sat, 29 Nov 2014 05:08:30 GMT (envelope-from hselasky@FreeBSD.org) Message-Id: <201411290508.sAT58UqA055494@svn.freebsd.org> X-Authentication-Warning: svn.freebsd.org: hselasky set sender to hselasky@FreeBSD.org using -f From: Hans Petter Selasky Date: Sat, 29 Nov 2014 05:08:30 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org Subject: svn commit: r275231 - stable/9/sys/kern X-SVN-Group: stable-9 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: Sat, 29 Nov 2014 05:08:30 -0000 Author: hselasky Date: Sat Nov 29 05:08:29 2014 New Revision: 275231 URL: https://svnweb.freebsd.org/changeset/base/275231 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/9/sys/kern/sys_generic.c Directory Properties: stable/9/sys/ (props changed) Modified: stable/9/sys/kern/sys_generic.c ============================================================================== --- stable/9/sys/kern/sys_generic.c Sat Nov 29 05:07:24 2014 (r275230) +++ stable/9/sys/kern/sys_generic.c Sat Nov 29 05:08:29 2014 (r275231) @@ -74,6 +74,20 @@ __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"); @@ -640,6 +654,7 @@ 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; @@ -674,17 +689,18 @@ 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 @@ -698,7 +714,8 @@ 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); }