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Block a bunch of threads on a futex and requeue them on another, N at a time. This program is particularly useful to measure the latency of nthread requeues without waking up any tasks -- thus mimicking a regular futex_wait. An example run: $ perf bench futex requeue -r 100 -t 64 Run summary [PID 151011]: Requeuing 64 threads (from 0x7d15c4 to 0x7d15c8), 1 at a time. [Run 1]: Requeued 64 of 64 threads in 0.0400 ms [Run 2]: Requeued 64 of 64 threads in 0.0390 ms [Run 3]: Requeued 64 of 64 threads in 0.0400 ms ... [Run 100]: Requeued 64 of 64 threads in 0.0390 ms Requeued 64 of 64 threads in 0.0399 ms (+-0.37%) Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Darren Hart <dvhart@linux.intel.com> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Cc: Darren Hart <dvhart@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jason Low <jason.low2@hp.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <Waiman.Long@hp.com> Link: http://lkml.kernel.org/r/1387081917-9102-4-git-send-email-davidlohr@hp.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
72 lines
2.2 KiB
C
72 lines
2.2 KiB
C
/*
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* Glibc independent futex library for testing kernel functionality.
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* Shamelessly stolen from Darren Hart <dvhltc@us.ibm.com>
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* http://git.kernel.org/cgit/linux/kernel/git/dvhart/futextest.git/
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*/
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#ifndef _FUTEX_H
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#define _FUTEX_H
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#include <unistd.h>
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#include <sys/syscall.h>
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#include <sys/types.h>
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#include <linux/futex.h>
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/**
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* futex() - SYS_futex syscall wrapper
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* @uaddr: address of first futex
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* @op: futex op code
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* @val: typically expected value of uaddr, but varies by op
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* @timeout: typically an absolute struct timespec (except where noted
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* otherwise). Overloaded by some ops
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* @uaddr2: address of second futex for some ops\
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* @val3: varies by op
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* @opflags: flags to be bitwise OR'd with op, such as FUTEX_PRIVATE_FLAG
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*
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* futex() is used by all the following futex op wrappers. It can also be
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* used for misuse and abuse testing. Generally, the specific op wrappers
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* should be used instead. It is a macro instead of an static inline function as
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* some of the types over overloaded (timeout is used for nr_requeue for
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* example).
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*
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* These argument descriptions are the defaults for all
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* like-named arguments in the following wrappers except where noted below.
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*/
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#define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \
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syscall(SYS_futex, uaddr, op | opflags, val, timeout, uaddr2, val3)
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/**
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* futex_wait() - block on uaddr with optional timeout
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* @timeout: relative timeout
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*/
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static inline int
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futex_wait(u_int32_t *uaddr, u_int32_t val, struct timespec *timeout, int opflags)
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{
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return futex(uaddr, FUTEX_WAIT, val, timeout, NULL, 0, opflags);
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}
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/**
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* futex_wake() - wake one or more tasks blocked on uaddr
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* @nr_wake: wake up to this many tasks
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*/
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static inline int
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futex_wake(u_int32_t *uaddr, int nr_wake, int opflags)
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{
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return futex(uaddr, FUTEX_WAKE, nr_wake, NULL, NULL, 0, opflags);
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}
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/**
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* futex_cmp_requeue() - requeue tasks from uaddr to uaddr2
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* @nr_wake: wake up to this many tasks
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* @nr_requeue: requeue up to this many tasks
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*/
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static inline int
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futex_cmp_requeue(u_int32_t *uaddr, u_int32_t val, u_int32_t *uaddr2, int nr_wake,
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int nr_requeue, int opflags)
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{
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return futex(uaddr, FUTEX_CMP_REQUEUE, nr_wake, nr_requeue, uaddr2,
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val, opflags);
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}
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#endif /* _FUTEX_H */
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