mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-23 07:26:16 +07:00
15df03c879
For a custom microbenchmark on a 3.30GHz Xeon SandyBridge, which calls
IPC_STAT over and over, it was calculated that, on avg the cost of
ipc_get_maxid() for increasing amounts of keys was:
10 keys: ~900 cycles
100 keys: ~15000 cycles
1000 keys: ~150000 cycles
10000 keys: ~2100000 cycles
This is unsurprising as maxid is currently O(n).
By having the max_id available in O(1) we save all those cycles for each
semctl(_STAT) command, the idr_find can be expensive -- which some real
(customer) workloads actually poll on.
Note that this used to be the case, until commit 7ca7e564e0 ("ipc:
store ipcs into IDRs"). The cost is the extra idr_find when doing
RMIDs, but we simply go backwards, and should not take too many
iterations to find the new value.
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170831172049.14576-5-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
239 lines
7.2 KiB
C
239 lines
7.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
/*
|
|
* linux/ipc/util.h
|
|
* Copyright (C) 1999 Christoph Rohland
|
|
*
|
|
* ipc helper functions (c) 1999 Manfred Spraul <manfred@colorfullife.com>
|
|
* namespaces support. 2006 OpenVZ, SWsoft Inc.
|
|
* Pavel Emelianov <xemul@openvz.org>
|
|
*/
|
|
|
|
#ifndef _IPC_UTIL_H
|
|
#define _IPC_UTIL_H
|
|
|
|
#include <linux/unistd.h>
|
|
#include <linux/err.h>
|
|
#include <linux/ipc_namespace.h>
|
|
|
|
#define SEQ_MULTIPLIER (IPCMNI)
|
|
|
|
int sem_init(void);
|
|
int msg_init(void);
|
|
void shm_init(void);
|
|
|
|
struct ipc_namespace;
|
|
|
|
#ifdef CONFIG_POSIX_MQUEUE
|
|
extern void mq_clear_sbinfo(struct ipc_namespace *ns);
|
|
extern void mq_put_mnt(struct ipc_namespace *ns);
|
|
#else
|
|
static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
|
|
static inline void mq_put_mnt(struct ipc_namespace *ns) { }
|
|
#endif
|
|
|
|
#ifdef CONFIG_SYSVIPC
|
|
int sem_init_ns(struct ipc_namespace *ns);
|
|
int msg_init_ns(struct ipc_namespace *ns);
|
|
int shm_init_ns(struct ipc_namespace *ns);
|
|
|
|
void sem_exit_ns(struct ipc_namespace *ns);
|
|
void msg_exit_ns(struct ipc_namespace *ns);
|
|
void shm_exit_ns(struct ipc_namespace *ns);
|
|
#else
|
|
static inline int sem_init_ns(struct ipc_namespace *ns) { return 0; }
|
|
static inline int msg_init_ns(struct ipc_namespace *ns) { return 0; }
|
|
static inline int shm_init_ns(struct ipc_namespace *ns) { return 0; }
|
|
|
|
static inline void sem_exit_ns(struct ipc_namespace *ns) { }
|
|
static inline void msg_exit_ns(struct ipc_namespace *ns) { }
|
|
static inline void shm_exit_ns(struct ipc_namespace *ns) { }
|
|
#endif
|
|
|
|
/*
|
|
* Structure that holds the parameters needed by the ipc operations
|
|
* (see after)
|
|
*/
|
|
struct ipc_params {
|
|
key_t key;
|
|
int flg;
|
|
union {
|
|
size_t size; /* for shared memories */
|
|
int nsems; /* for semaphores */
|
|
} u; /* holds the getnew() specific param */
|
|
};
|
|
|
|
/*
|
|
* Structure that holds some ipc operations. This structure is used to unify
|
|
* the calls to sys_msgget(), sys_semget(), sys_shmget()
|
|
* . routine to call to create a new ipc object. Can be one of newque,
|
|
* newary, newseg
|
|
* . routine to call to check permissions for a new ipc object.
|
|
* Can be one of security_msg_associate, security_sem_associate,
|
|
* security_shm_associate
|
|
* . routine to call for an extra check if needed
|
|
*/
|
|
struct ipc_ops {
|
|
int (*getnew)(struct ipc_namespace *, struct ipc_params *);
|
|
int (*associate)(struct kern_ipc_perm *, int);
|
|
int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
|
|
};
|
|
|
|
struct seq_file;
|
|
struct ipc_ids;
|
|
|
|
int ipc_init_ids(struct ipc_ids *);
|
|
#ifdef CONFIG_PROC_FS
|
|
void __init ipc_init_proc_interface(const char *path, const char *header,
|
|
int ids, int (*show)(struct seq_file *, void *));
|
|
#else
|
|
#define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
|
|
#endif
|
|
|
|
#define IPC_SEM_IDS 0
|
|
#define IPC_MSG_IDS 1
|
|
#define IPC_SHM_IDS 2
|
|
|
|
#define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
|
|
#define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)
|
|
#define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX)
|
|
|
|
/* must be called with ids->rwsem acquired for writing */
|
|
int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
|
|
|
|
/* must be called with both locks acquired. */
|
|
void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
|
|
|
|
/* must be called with both locks acquired. */
|
|
void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
|
|
|
|
/* must be called with ipcp locked */
|
|
int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
|
|
|
|
/**
|
|
* ipc_get_maxid - get the last assigned id
|
|
* @ids: ipc identifier set
|
|
*
|
|
* Called with ipc_ids.rwsem held for reading.
|
|
*/
|
|
static inline int ipc_get_maxid(struct ipc_ids *ids)
|
|
{
|
|
if (ids->in_use == 0)
|
|
return -1;
|
|
|
|
if (ids->in_use == IPCMNI)
|
|
return IPCMNI - 1;
|
|
|
|
return ids->max_id;
|
|
}
|
|
|
|
/*
|
|
* For allocation that need to be freed by RCU.
|
|
* Objects are reference counted, they start with reference count 1.
|
|
* getref increases the refcount, the putref call that reduces the recount
|
|
* to 0 schedules the rcu destruction. Caller must guarantee locking.
|
|
*
|
|
* refcount is initialized by ipc_addid(), before that point call_rcu()
|
|
* must be used.
|
|
*/
|
|
int ipc_rcu_getref(struct kern_ipc_perm *ptr);
|
|
void ipc_rcu_putref(struct kern_ipc_perm *ptr,
|
|
void (*func)(struct rcu_head *head));
|
|
|
|
struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
|
|
struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
|
|
|
|
void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
|
|
void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
|
|
int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
|
|
struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
|
|
struct ipc_ids *ids, int id, int cmd,
|
|
struct ipc64_perm *perm, int extra_perm);
|
|
|
|
#ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
|
|
/* On IA-64, we always use the "64-bit version" of the IPC structures. */
|
|
# define ipc_parse_version(cmd) IPC_64
|
|
#else
|
|
int ipc_parse_version(int *cmd);
|
|
#endif
|
|
|
|
extern void free_msg(struct msg_msg *msg);
|
|
extern struct msg_msg *load_msg(const void __user *src, size_t len);
|
|
extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
|
|
extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
|
|
|
|
static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
|
|
{
|
|
return uid / SEQ_MULTIPLIER != ipcp->seq;
|
|
}
|
|
|
|
static inline void ipc_lock_object(struct kern_ipc_perm *perm)
|
|
{
|
|
spin_lock(&perm->lock);
|
|
}
|
|
|
|
static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
|
|
{
|
|
spin_unlock(&perm->lock);
|
|
}
|
|
|
|
static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
|
|
{
|
|
assert_spin_locked(&perm->lock);
|
|
}
|
|
|
|
static inline void ipc_unlock(struct kern_ipc_perm *perm)
|
|
{
|
|
ipc_unlock_object(perm);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/*
|
|
* ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
|
|
* where the respective ipc_ids.rwsem is not being held down.
|
|
* Checks whether the ipc object is still around or if it's gone already, as
|
|
* ipc_rmid() may have already freed the ID while the ipc lock was spinning.
|
|
* Needs to be called with kern_ipc_perm.lock held -- exception made for one
|
|
* checkpoint case at sys_semtimedop() as noted in code commentary.
|
|
*/
|
|
static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
|
|
{
|
|
return !perm->deleted;
|
|
}
|
|
|
|
struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
|
|
int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
|
|
const struct ipc_ops *ops, struct ipc_params *params);
|
|
void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
|
|
void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
#include <linux/compat.h>
|
|
struct compat_ipc_perm {
|
|
key_t key;
|
|
__compat_uid_t uid;
|
|
__compat_gid_t gid;
|
|
__compat_uid_t cuid;
|
|
__compat_gid_t cgid;
|
|
compat_mode_t mode;
|
|
unsigned short seq;
|
|
};
|
|
|
|
void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
|
|
void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
|
|
int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
|
|
int get_compat_ipc64_perm(struct ipc64_perm *,
|
|
struct compat_ipc64_perm __user *);
|
|
|
|
static inline int compat_ipc_parse_version(int *cmd)
|
|
{
|
|
#ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
|
|
int version = *cmd & IPC_64;
|
|
*cmd &= ~IPC_64;
|
|
return version;
|
|
#else
|
|
return IPC_64;
|
|
#endif
|
|
}
|
|
#endif
|
|
#endif
|