freebsd-nq/sys/sys/_lockmgr.h
Mateusz Guzik eac22dd480 lockmgr: shrink struct lock by 8 bytes on LP64
Currently the struct has a 4 byte padding stemming from 3 ints.

1. prio comfortably fits in short, unfortunately there is no dedicated
   type for it and plumbing it throughout the codebase is not worth it
   right now, instead an assert is added which covers also flags for
   safety
2. lk_exslpfail can in principle exceed u_short, but the count is
   already not considered reliable and it only ever gets modified
   straight to 0. In other words it can be incrementing with an upper
   bound of USHRT_MAX

With these in place struct lock shrinks from 48 to 40 bytes.

Reviewed by:	kib (previous version)
Differential Revision:	https://reviews.freebsd.org/D28680
2021-02-15 13:57:25 +00:00

52 lines
1.8 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2008 Attilio Rao <attilio@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice(s), this list of conditions and the following disclaimer as
* the first lines of this file unmodified other than the possible
* addition of one or more copyright notices.
* 2. Redistributions in binary form must reproduce the above copyright
* notice(s), this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* $FreeBSD$
*/
#ifndef _SYS__LOCKMGR_H_
#define _SYS__LOCKMGR_H_
#ifdef DEBUG_LOCKS
#include <sys/_stack.h>
#endif
struct lock {
struct lock_object lock_object;
volatile uintptr_t lk_lock;
u_short lk_exslpfail;
u_short lk_pri;
int lk_timo;
#ifdef DEBUG_LOCKS
struct stack lk_stack;
#endif
};
#endif