Messages in this thread | | | Date | Tue, 19 Oct 2021 13:56:32 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v2 1/2] perf bench futex: Use a 64-bit time_t |
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Em Fri, Oct 15, 2021 at 10:56:33AM +1000, Alistair Francis escreveu: > From: Alistair Francis <alistair.francis@wdc.com> > > Convert tools/perf to only use a 64-bit time_t. On 64-bit architectures > this isn't a functional change. On 32-bit architectures we now only > perform 64-bit time_t syscalls (__NR_futex_time64) and use a struct > timespec64. > > This won't work on kernels before 5.1, but as perf is tied to the kernel > that's ok.
No, perf is not tied to the kernel, one can use a new perf tool on any previous kernel, and an old perf tool should work on new kernels as well.
- Arnaldo
> This allows us to build perf for 32-bit architectures with 64-bit time_t > like RISC-V 32-bit. > > Signed-off-by: Alistair Francis <alistair.francis@wdc.com> > --- > tools/perf/bench/futex.h | 26 ++++++++++++++++++++------ > 1 file changed, 20 insertions(+), 6 deletions(-) > > diff --git a/tools/perf/bench/futex.h b/tools/perf/bench/futex.h > index b3853aac3021c..b9665d43d2988 100644 > --- a/tools/perf/bench/futex.h > +++ b/tools/perf/bench/futex.h > @@ -12,6 +12,7 @@ > #include <sys/syscall.h> > #include <sys/types.h> > #include <linux/futex.h> > +#include <linux/time_types.h> > > struct bench_futex_parameters { > bool silent; > @@ -27,12 +28,14 @@ struct bench_futex_parameters { > unsigned int nrequeue; > }; > > +#define timespec64 __kernel_timespec > + > /** > * futex() - SYS_futex syscall wrapper > * @uaddr: address of first futex > * @op: futex op code > * @val: typically expected value of uaddr, but varies by op > - * @timeout: typically an absolute struct timespec (except where noted > + * @timeout: typically an absolute struct timespec64 (except where noted > * otherwise). Overloaded by some ops > * @uaddr2: address of second futex for some ops > * @val3: varies by op > @@ -47,15 +50,26 @@ struct bench_futex_parameters { > * These argument descriptions are the defaults for all > * like-named arguments in the following wrappers except where noted below. > */ > -#define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \ > - syscall(SYS_futex, uaddr, op | opflags, val, timeout, uaddr2, val3) > +/** > + * We only support 64-bit time_t for the timeout. > + * On 64-bit architectures we can use __NR_futex > + * On 32-bit architectures we use __NR_futex_time64. This only works on kernel > + * versions 5.1+. > + */ > +#if __BITS_PER_LONG == 64 > +# define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \ > + syscall(__NR_futex, uaddr, op | opflags, val, timeout, uaddr2, val3) > +#else > +# define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \ > + syscall(__NR_futex_time64, uaddr, op | opflags, val, timeout, uaddr2, val3) > +#endif > > /** > * futex_wait() - block on uaddr with optional timeout > * @timeout: relative timeout > */ > static inline int > -futex_wait(u_int32_t *uaddr, u_int32_t val, struct timespec *timeout, int opflags) > +futex_wait(u_int32_t *uaddr, u_int32_t val, struct timespec64 *timeout, int opflags) > { > return futex(uaddr, FUTEX_WAIT, val, timeout, NULL, 0, opflags); > } > @@ -74,7 +88,7 @@ futex_wake(u_int32_t *uaddr, int nr_wake, int opflags) > * futex_lock_pi() - block on uaddr as a PI mutex > */ > static inline int > -futex_lock_pi(u_int32_t *uaddr, struct timespec *timeout, int opflags) > +futex_lock_pi(u_int32_t *uaddr, struct timespec64 *timeout, int opflags) > { > return futex(uaddr, FUTEX_LOCK_PI, 0, timeout, NULL, 0, opflags); > } > @@ -111,7 +125,7 @@ futex_cmp_requeue(u_int32_t *uaddr, u_int32_t val, u_int32_t *uaddr2, int nr_wak > */ > static inline int > futex_wait_requeue_pi(u_int32_t *uaddr, u_int32_t val, u_int32_t *uaddr2, > - struct timespec *timeout, int opflags) > + struct timespec64 *timeout, int opflags) > { > return futex(uaddr, FUTEX_WAIT_REQUEUE_PI, val, timeout, uaddr2, 0, > opflags); > -- > 2.31.1
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- Arnaldo
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