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SubjectRe: [PATCH v2 1/2] perf bench futex: Use a 64-bit time_t
On Wed, Oct 20, 2021 at 2:56 AM Arnaldo Carvalho de Melo
<arnaldo.melo@gmail.com> wrote:
>
> 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.

+ André, I won't be doing this the way you requested

Ok, so back to the previous version then. I'll send the patches soon.

Alistair

>
> - 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
>
> --
>
> - Arnaldo

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