[fio.git] / syslet.h

#ifndef _LINUX_SYSLET_H
#define _LINUX_SYSLET_H
/*
 * The syslet subsystem - asynchronous syscall execution support.
 *
 * Started by Ingo Molnar:
 *
 *  Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 *
 * User-space API/ABI definitions:
 */

/*
 * This is the 'Syslet Atom' - the basic unit of execution
 * within the syslet framework. A syslet always represents
 * a single system-call plus its arguments, plus has conditions
 * attached to it that allows the construction of larger
 * programs from these atoms. User-space variables can be used
 * (for example a loop index) via the special sys_umem*() syscalls.
 *
 * Arguments are implemented via pointers to arguments. This not
 * only increases the flexibility of syslet atoms (multiple syslets
 * can share the same variable for example), but is also an
 * optimization: copy_uatom() will only fetch syscall parameters
 * up until the point it meets the first NULL pointer. 50% of all
 * syscalls have 2 or less parameters (and 90% of all syscalls have
 * 4 or less parameters).
 *
 * [ Note: since the argument array is at the end of the atom, and the
 *   kernel will not touch any argument beyond the final NULL one, atoms
 *   might be packed more tightly. (the only special case exception to
 *   this rule would be SKIP_TO_NEXT_ON_STOP atoms, where the kernel will
 *   jump a full syslet_uatom number of bytes.) ]
 */
struct syslet_uatom {
	unsigned long				flags;
	unsigned long				nr;
	long __user				*ret_ptr;
	struct syslet_uatom	__user		*next;
	unsigned long		__user		*arg_ptr[6];
	/*
	 * User-space can put anything in here, kernel will not
	 * touch it:
	 */
	void __user				*private;
};

/*
 * Flags to modify/control syslet atom behavior:
 */

/*
 * Immediately queue this syslet asynchronously - do not even
 * attempt to execute it synchronously in the user context:
 */
#define SYSLET_ASYNC				0x00000001

/*
 * Never queue this syslet asynchronously - even if synchronous
 * execution causes a context-switching:
 */
#define SYSLET_SYNC				0x00000002

/*
 * Do not queue the syslet in the completion ring when done.
 *
 * ( the default is that the final atom of a syslet is queued
 *   in the completion ring. )
 *
 * Some syscalls generate implicit completion events of their
 * own.
 */
#define SYSLET_NO_COMPLETE			0x00000004

/*
 * Execution control: conditions upon the return code
 * of the previous syslet atom. 'Stop' means syslet
 * execution is stopped and the atom is put into the
 * completion ring:
 */
#define SYSLET_STOP_ON_NONZERO			0x00000008
#define SYSLET_STOP_ON_ZERO			0x00000010
#define SYSLET_STOP_ON_NEGATIVE			0x00000020
#define SYSLET_STOP_ON_NON_POSITIVE		0x00000040

#define SYSLET_STOP_MASK				\
	(	SYSLET_STOP_ON_NONZERO		|	\
		SYSLET_STOP_ON_ZERO		|	\
		SYSLET_STOP_ON_NEGATIVE		|	\
		SYSLET_STOP_ON_NON_POSITIVE		)

/*
 * Special modifier to 'stop' handling: instead of stopping the
 * execution of the syslet, the linearly next syslet is executed.
 * (Normal execution flows along atom->next, and execution stops
 *  if atom->next is NULL or a stop condition becomes true.)
 *
 * This is what allows true branches of execution within syslets.
 */
#define SYSLET_SKIP_TO_NEXT_ON_STOP		0x00000080

/*
 * This is the (per-user-context) descriptor of the async completion
 * ring. This gets registered via sys_async_register().
 */
struct async_head_user {
	/*
	 * Pointers to completed async syslets (i.e. syslets that
	 * generated a cachemiss and went async, returning -EASYNCSYSLET
	 * to the user context by sys_async_exec()) are queued here.
	 * Syslets that were executed synchronously are not queued here.
	 *
	 * Note: the final atom that generated the exit condition is
	 * queued here. Normally this would be the last atom of a syslet.
	 */
	struct syslet_uatom __user		**completion_ring;
	/*
	 * Ring size in bytes:
	 */
	unsigned long				ring_size_bytes;

	/*
	 * Maximum number of asynchronous contexts the kernel creates.
	 *
	 * -1UL has a special meaning: the kernel manages the optimal
	 * size of the async pool.
	 *
	 * Note: this field should be valid for the lifetime of async
	 * processing, because future kernels detect changes to this
	 * field. (enabling user-space to control the size of the async
	 * pool in a low-overhead fashion)
	 */
	unsigned long				max_nr_threads;
};

#endif
Commit	Line	Data
a4f4fdd7 JA	1	#ifndef _LINUX_SYSLET_H
	2	#define _LINUX_SYSLET_H
	3	/*
	4	* The syslet subsystem - asynchronous syscall execution support.
	5	*
	6	* Started by Ingo Molnar:
	7	*
	8	* Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
	9	*
	10	* User-space API/ABI definitions:
	11	*/
	12
	13	/*
	14	* This is the 'Syslet Atom' - the basic unit of execution
	15	* within the syslet framework. A syslet always represents
	16	* a single system-call plus its arguments, plus has conditions
	17	* attached to it that allows the construction of larger
	18	* programs from these atoms. User-space variables can be used
	19	* (for example a loop index) via the special sys_umem*() syscalls.
	20	*
	21	* Arguments are implemented via pointers to arguments. This not
	22	* only increases the flexibility of syslet atoms (multiple syslets
	23	* can share the same variable for example), but is also an
	24	* optimization: copy_uatom() will only fetch syscall parameters
	25	* up until the point it meets the first NULL pointer. 50% of all
	26	* syscalls have 2 or less parameters (and 90% of all syscalls have
	27	* 4 or less parameters).
	28	*
	29	* [ Note: since the argument array is at the end of the atom, and the
	30	* kernel will not touch any argument beyond the final NULL one, atoms
	31	* might be packed more tightly. (the only special case exception to
	32	* this rule would be SKIP_TO_NEXT_ON_STOP atoms, where the kernel will
	33	* jump a full syslet_uatom number of bytes.) ]
	34	*/
	35	struct syslet_uatom {
	36	unsigned long flags;
	37	unsigned long nr;
	38	long __user *ret_ptr;
	39	struct syslet_uatom __user *next;
	40	unsigned long __user *arg_ptr[6];
	41	/*
	42	* User-space can put anything in here, kernel will not
	43	* touch it:
	44	*/
	45	void __user *private;
	46	};
	47
	48	/*
	49	* Flags to modify/control syslet atom behavior:
	50	*/
	51
	52	/*
	53	* Immediately queue this syslet asynchronously - do not even
	54	* attempt to execute it synchronously in the user context:
	55	*/
	56	#define SYSLET_ASYNC 0x00000001
	57
	58	/*
	59	* Never queue this syslet asynchronously - even if synchronous
	60	* execution causes a context-switching:
	61	*/
	62	#define SYSLET_SYNC 0x00000002
	63
	64	/*
65	* Do not queue the syslet in the completion ring when done.
66	*
67	* ( the default is that the final atom of a syslet is queued
68	* in the completion ring. )
69	*
70	* Some syscalls generate implicit completion events of their
71	* own.
72	*/
73	#define SYSLET_NO_COMPLETE 0x00000004
74
75	/*
76	* Execution control: conditions upon the return code
77	* of the previous syslet atom. 'Stop' means syslet
78	* execution is stopped and the atom is put into the
79	* completion ring:
80	*/
81	#define SYSLET_STOP_ON_NONZERO 0x00000008
82	#define SYSLET_STOP_ON_ZERO 0x00000010
83	#define SYSLET_STOP_ON_NEGATIVE 0x00000020
84	#define SYSLET_STOP_ON_NON_POSITIVE 0x00000040
85
86	#define SYSLET_STOP_MASK \
87	( SYSLET_STOP_ON_NONZERO \| \
88	SYSLET_STOP_ON_ZERO \| \
89	SYSLET_STOP_ON_NEGATIVE \| \
90	SYSLET_STOP_ON_NON_POSITIVE )
91
92	/*
93	* Special modifier to 'stop' handling: instead of stopping the
94	* execution of the syslet, the linearly next syslet is executed.
95	* (Normal execution flows along atom->next, and execution stops
96	* if atom->next is NULL or a stop condition becomes true.)
97	*
98	* This is what allows true branches of execution within syslets.
99	*/
100	#define SYSLET_SKIP_TO_NEXT_ON_STOP 0x00000080
101
102	/*
103	* This is the (per-user-context) descriptor of the async completion
104	* ring. This gets registered via sys_async_register().
105	*/
106	struct async_head_user {
107	/*
108	* Pointers to completed async syslets (i.e. syslets that
109	* generated a cachemiss and went async, returning -EASYNCSYSLET
110	* to the user context by sys_async_exec()) are queued here.
111	* Syslets that were executed synchronously are not queued here.
112	*
113	* Note: the final atom that generated the exit condition is
114	* queued here. Normally this would be the last atom of a syslet.
115	*/
116	struct syslet_uatom __user **completion_ring;
117	/*
118	* Ring size in bytes:
119	*/
120	unsigned long ring_size_bytes;
121
122	/*
123	* Maximum number of asynchronous contexts the kernel creates.
124	*
125	* -1UL has a special meaning: the kernel manages the optimal
126	* size of the async pool.
127	*
128	* Note: this field should be valid for the lifetime of async
129	* processing, because future kernels detect changes to this
130	* field. (enabling user-space to control the size of the async
131	* pool in a low-overhead fashion)
132	*/
133	unsigned long max_nr_threads;
134	};
135
136	#endif