All of lore.kernel.org
 help / color / mirror / Atom feed
From: "André Almeida" <andrealmeid@collabora.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Alistair Francis <alistair.francis@opensource.wdc.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Alistair Francis <alistair23@gmail.com>,
	linux-riscv <linux-riscv@lists.infradead.org>,
	Namhyung Kim <namhyung@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
	linux-perf-users@vger.kernel.org,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Darren Hart <dvhart@infradead.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Atish Patra <atish.patra@wdc.com>,
	Alistair Francis <alistair.francis@wdc.com>
Subject: Re: [PATCH v3 2/2] perf bench: Add support for 32-bit systems with 64-bit time_t
Date: Tue, 21 Sep 2021 20:06:21 -0300	[thread overview]
Message-ID: <9db8c79a-f704-84ce-360b-84335f926a48@collabora.com> (raw)
In-Reply-To: <CAK8P3a3x_EyCiPDpMK54y=Rtm-Wb08ym2TNiuAZgXhYrThcWTw@mail.gmail.com>

Às 05:08 de 21/09/21, Arnd Bergmann escreveu:
> On Tue, Sep 21, 2021 at 12:47 AM André Almeida
> <andrealmeid@collabora.com> wrote:
>>
>> #if defined(__i386__) || __TIMESIZE == 32
>> # define NR_gettime64 __NR_clock_gettime64
>> #else
>> # define NR_gettime64 __NR_clock_gettime
>> #endif
>>
>> struct timespec64 {
>>         long long tv_sec;       /* seconds */
>>         long long tv_nsec;      /* nanoseconds */
>> };
>>
>> int gettime64(clock_t clockid, struct timespec64 *tv)
>> {
>>         return syscall(NR_gettime64, clockid, tv);
>> }
>>
>> Then we can just use &timeout at __NR_futex_time64 for 32bit arch and at
>> __NR_futex for 64bit arch.
> 
> This is still broken when you disable CONFIG_COMPAT_32BIT_TIME,
> which disables all system calls that take time32 arguments.
> 

Oh, I think my point was confusing then. My suggestion was to use only
the futex entry points that accepts time64, and to always use
clock_gettime that uses time64, for all platforms. Then it will work if
we disable CONFIG_COMPAT_32BIT_TIME.

>> This might be a simpler solution to the problem that you are facing but
>> I'm not entirely sure. Also, futex's selftests do use the timeout
>> argument and I think that they also won't compile in 32-bit RISC-V, so
>> maybe we can start from there so we can actually test the timeout
>> argument and check if it's working.
> 
> I would love to see the wrapper that Alistair wrote as part of some kernel
> uapi header provided to user space. futex is used by tons of applications,
> and we never had a library abstraction for it, so everyone has to do these
> by hand, and they all get them slightly wrong in different ways.

Why we don't have a futex() wrapper at glibc as we do have for others
syscalls?

> 
> We normally don't do this in kernel headers, but I think the benefits
> would be far greater compared to today's situation.
> 
>       Arnd
> 

WARNING: multiple messages have this Message-ID
From: "André Almeida" <andrealmeid@collabora.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Alistair Francis <alistair.francis@opensource.wdc.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Alistair Francis <alistair23@gmail.com>,
	linux-riscv <linux-riscv@lists.infradead.org>,
	Namhyung Kim <namhyung@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
	linux-perf-users@vger.kernel.org,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Darren Hart <dvhart@infradead.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Atish Patra <atish.patra@wdc.com>,
	Alistair Francis <alistair.francis@wdc.com>
Subject: Re: [PATCH v3 2/2] perf bench: Add support for 32-bit systems with 64-bit time_t
Date: Tue, 21 Sep 2021 20:06:21 -0300	[thread overview]
Message-ID: <9db8c79a-f704-84ce-360b-84335f926a48@collabora.com> (raw)
In-Reply-To: <CAK8P3a3x_EyCiPDpMK54y=Rtm-Wb08ym2TNiuAZgXhYrThcWTw@mail.gmail.com>

Às 05:08 de 21/09/21, Arnd Bergmann escreveu:
> On Tue, Sep 21, 2021 at 12:47 AM André Almeida
> <andrealmeid@collabora.com> wrote:
>>
>> #if defined(__i386__) || __TIMESIZE == 32
>> # define NR_gettime64 __NR_clock_gettime64
>> #else
>> # define NR_gettime64 __NR_clock_gettime
>> #endif
>>
>> struct timespec64 {
>>         long long tv_sec;       /* seconds */
>>         long long tv_nsec;      /* nanoseconds */
>> };
>>
>> int gettime64(clock_t clockid, struct timespec64 *tv)
>> {
>>         return syscall(NR_gettime64, clockid, tv);
>> }
>>
>> Then we can just use &timeout at __NR_futex_time64 for 32bit arch and at
>> __NR_futex for 64bit arch.
> 
> This is still broken when you disable CONFIG_COMPAT_32BIT_TIME,
> which disables all system calls that take time32 arguments.
> 

Oh, I think my point was confusing then. My suggestion was to use only
the futex entry points that accepts time64, and to always use
clock_gettime that uses time64, for all platforms. Then it will work if
we disable CONFIG_COMPAT_32BIT_TIME.

>> This might be a simpler solution to the problem that you are facing but
>> I'm not entirely sure. Also, futex's selftests do use the timeout
>> argument and I think that they also won't compile in 32-bit RISC-V, so
>> maybe we can start from there so we can actually test the timeout
>> argument and check if it's working.
> 
> I would love to see the wrapper that Alistair wrote as part of some kernel
> uapi header provided to user space. futex is used by tons of applications,
> and we never had a library abstraction for it, so everyone has to do these
> by hand, and they all get them slightly wrong in different ways.

Why we don't have a futex() wrapper at glibc as we do have for others
syscalls?

> 
> We normally don't do this in kernel headers, but I think the benefits
> would be far greater compared to today's situation.
> 
>       Arnd
> 

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  reply	other threads:[~2021-09-21 23:06 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-17  6:10 [PATCH v3 1/2] perf benchmark: Call the futex syscall from a function Alistair Francis
2021-09-17  6:10 ` Alistair Francis
2021-09-17  6:10 ` [PATCH v3 2/2] perf bench: Add support for 32-bit systems with 64-bit time_t Alistair Francis
2021-09-17  6:10   ` Alistair Francis
2021-09-17  7:33   ` Arnd Bergmann
2021-09-17  7:33     ` Arnd Bergmann
2021-09-17 18:33   ` Davidlohr Bueso
2021-09-17 18:33     ` Davidlohr Bueso
2021-09-20 22:47   ` André Almeida
2021-09-20 22:47     ` André Almeida
2021-09-21  8:08     ` Arnd Bergmann
2021-09-21  8:08       ` Arnd Bergmann
2021-09-21 23:06       ` André Almeida [this message]
2021-09-21 23:06         ` André Almeida
2021-09-22 11:26         ` Arnd Bergmann
2021-09-22 11:26           ` Arnd Bergmann
2021-09-22 11:27         ` Arnd Bergmann
2021-09-22 11:27           ` Arnd Bergmann
2021-09-24  4:34       ` Alistair Francis
2021-09-24  4:34         ` Alistair Francis
2021-09-24  4:34     ` Alistair Francis
2021-09-24  4:34       ` Alistair Francis
2021-09-26 21:32       ` André Almeida
2021-09-26 21:32         ` André Almeida
2021-09-17 18:21 ` [PATCH v3 1/2] perf benchmark: Call the futex syscall from a function Davidlohr Bueso
2021-09-17 18:21   ` Davidlohr Bueso

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=9db8c79a-f704-84ce-360b-84335f926a48@collabora.com \
    --to=andrealmeid@collabora.com \
    --cc=acme@kernel.org \
    --cc=alexander.shishkin@linux.intel.com \
    --cc=alistair.francis@opensource.wdc.com \
    --cc=alistair.francis@wdc.com \
    --cc=alistair23@gmail.com \
    --cc=arnd@arndb.de \
    --cc=atish.patra@wdc.com \
    --cc=dave@stgolabs.net \
    --cc=dvhart@infradead.org \
    --cc=jolsa@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-perf-users@vger.kernel.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=mark.rutland@arm.com \
    --cc=mingo@redhat.com \
    --cc=namhyung@kernel.org \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --subject='Re: [PATCH v3 2/2] perf bench: Add support for 32-bit systems with 64-bit time_t' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.