| 87347f14 | 10-Oct-2024 |
Uros Bizjak <[email protected]> |
futex: Use atomic64_try_cmpxchg_relaxed() in get_inode_sequence_number()
Optimize get_inode_sequence_number() to use simpler and faster:
!atomic64_try_cmpxchg_relaxed(*ptr, &old, new)
instead of
futex: Use atomic64_try_cmpxchg_relaxed() in get_inode_sequence_number()
Optimize get_inode_sequence_number() to use simpler and faster:
!atomic64_try_cmpxchg_relaxed(*ptr, &old, new)
instead of:
atomic64_cmpxchg relaxed(*ptr, old, new) != old
The x86 CMPXCHG instruction returns success in ZF flag, so
this change saves a compare after cmpxchg. The generated
code improves from:
3da: 31 c0 xor %eax,%eax
3dc: f0 48 0f b1 8a 38 01 lock cmpxchg %rcx,0x138(%rdx)
3e3: 00 00
3e5: 48 85 c0 test %rax,%rax
3e8: 48 0f 44 c1 cmove %rcx,%rax
to:
3da: 31 c0 xor %eax,%eax
3dc: f0 48 0f b1 8a 38 01 lock cmpxchg %rcx,0x138(%rdx)
3e3: 00 00
3e5: 48 0f 44 c1 cmove %rcx,%rax
Signed-off-by: Uros Bizjak <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: André Almeida <[email protected]>
Link: https://lore.kernel.org/all/[email protected]
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|
| e9a56c93 | 13-Jun-2023 |
Jens Axboe <[email protected]> |
futex: make the vectored futex operations available
Rename unqueue_multiple() as futex_unqueue_multiple(), and make both
that and futex_wait_multiple_setup() available for external users. This
is in
futex: make the vectored futex operations available
Rename unqueue_multiple() as futex_unqueue_multiple(), and make both
that and futex_wait_multiple_setup() available for external users. This
is in preparation for wiring up vectored waits in io_uring.
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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| 5177c0cb | 13-Jun-2023 |
Jens Axboe <[email protected]> |
futex: make futex_parse_waitv() available as a helper
To make it more generically useful, augment it with allowing the caller
to pass in the wake handler and wake data. Convert the futex_waitv()
sys
futex: make futex_parse_waitv() available as a helper
To make it more generically useful, augment it with allowing the caller
to pass in the wake handler and wake data. Convert the futex_waitv()
syscall, passing in the default handlers.
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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|
| e52c4340 | 12-Jul-2023 |
Jens Axboe <[email protected]> |
futex: abstract out a __futex_wake_mark() helper
Move the unqueue and lock_ptr clear into a helper that futex_wake_mark()
calls. Add it to the public functions as well, in preparation for using
it o
futex: abstract out a __futex_wake_mark() helper
Move the unqueue and lock_ptr clear into a helper that futex_wake_mark()
calls. Add it to the public functions as well, in preparation for using
it outside the core futex code.
Suggested-by: Peter Zijlstra <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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| 12a4be50 | 08-Jun-2023 |
Jens Axboe <[email protected]> |
futex: factor out the futex wake handling
In preparation for having another waker that isn't futex_wake_mark(),
add a wake handler in futex_q. No extra data is associated with the
handler outside of
futex: factor out the futex wake handling
In preparation for having another waker that isn't futex_wake_mark(),
add a wake handler in futex_q. No extra data is associated with the
handler outside of struct futex_q itself. futex_wake_mark() is defined as
the standard wakeup helper, now set through futex_q_init like other
defaults.
Normal sync futex waiting relies on wake_q holding tasks that should
be woken up. This is what futex_wake_mark() does, it'll unqueue the
futex and add the associated task to the wake queue. For async usage of
futex waiting, rather than having tasks sleeping on the futex, we'll
need to deal with a futex wake differently. For the planned io_uring
case, that means posting a completion event for the task in question.
Having a definable wake handler can help support that use case.
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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