| epoch.9 (320686674b3c8ce3ffe135c421a22d063917ee46) | epoch.9 (8965b3033ea1750f2e064a130cf2f2158c6fc795) |
|---|---|
| 1.\" 2.\" Copyright (C) 2018 Matthew Macy <mmacy@FreeBSD.org>. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as --- 253 unchanged lines hidden (view full) --- 262More general mutation or a synchronous 263free would have to follow a call to 264.Fn epoch_wait . 265.Sh NOTES 266The 267.Nm 268kernel programming interface is under development and is subject to change. 269.Sh SEE ALSO | 1.\" 2.\" Copyright (C) 2018 Matthew Macy <mmacy@FreeBSD.org>. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as --- 253 unchanged lines hidden (view full) --- 262More general mutation or a synchronous 263free would have to follow a call to 264.Fn epoch_wait . 265.Sh NOTES 266The 267.Nm 268kernel programming interface is under development and is subject to change. 269.Sh SEE ALSO |
| 270.Xr callout 9 , |
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| 270.Xr locking 9 , 271.Xr mtx_pool 9 , 272.Xr mutex 9 , 273.Xr rwlock 9 , 274.Xr sema 9 , 275.Xr sleep 9 , | 271.Xr locking 9 , 272.Xr mtx_pool 9 , 273.Xr mutex 9 , 274.Xr rwlock 9 , 275.Xr sema 9 , 276.Xr sleep 9 , |
| 276.Xr sx 9 , 277.Xr timeout 9 | 277.Xr sx 9 |
| 278.Sh HISTORY 279The 280.Nm 281framework first appeared in 282.Fx 11.0 . 283.Sh CAVEATS 284One must be cautious when using 285.Fn epoch_wait_preempt . 286Threads are pinned during epoch sections, so if a thread in a section is then 287preempted by a higher priority compute bound thread on that CPU, it can be 288prevented from leaving the section indefinitely. 289.Pp 290Epochs are not a straight replacement for read locks. 291Callers must use safe list and tailq traversal routines in an epoch (see ck_queue). 292When modifying a list referenced from an epoch section safe removal 293routines must be used and the caller can no longer modify a list entry 294in place. 295An item to be modified must be handled with copy on write 296and frees must be deferred until after a grace period has elapsed. | 278.Sh HISTORY 279The 280.Nm 281framework first appeared in 282.Fx 11.0 . 283.Sh CAVEATS 284One must be cautious when using 285.Fn epoch_wait_preempt . 286Threads are pinned during epoch sections, so if a thread in a section is then 287preempted by a higher priority compute bound thread on that CPU, it can be 288prevented from leaving the section indefinitely. 289.Pp 290Epochs are not a straight replacement for read locks. 291Callers must use safe list and tailq traversal routines in an epoch (see ck_queue). 292When modifying a list referenced from an epoch section safe removal 293routines must be used and the caller can no longer modify a list entry 294in place. 295An item to be modified must be handled with copy on write 296and frees must be deferred until after a grace period has elapsed. |