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Groups > linux.kernel > #1345117
| From | Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread |
| Date | 2016-02-28 01:00 +0100 |
| Message-ID | <r6WWe-23d-1@gated-at.bofh.it> (permalink) |
| References | (3 earlier) <r6Bf4-370-15@gated-at.bofh.it> <r6Gy5-7hl-3@gated-at.bofh.it> <r6NSW-4fA-5@gated-at.bofh.it> <r6OvE-4uv-9@gated-at.bofh.it> <r6RWy-76H-13@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
----- On Feb 27, 2016, at 1:35 PM, Linus Torvalds torvalds@linux-foundation.org wrote:
> On Sat, Feb 27, 2016 at 6:58 AM, Peter Zijlstra <peterz@infradead.org> wrote:
>>
>> Paul's patches have the following structure:
>>
>> struct thread_local_abi {
>> union {
>> struct {
>> u32 cpu_id;
>> u32 seq;
>> };
>> u64 cpu_seq;
>> };
>> unsigned long post_commit_ip;
>> };
>
> Please don't do "unsigned long" in ABI structures any more.
>
> Make it u64, and make sure it is 64-bit aligned (which it would be in
> this case). Make it so that we don't have to have separate compat
> paths.
AFAIU, this "post_commit_ip" field is expected to be updated
with a single-copy-store by user-space. If we want to handle both
32-bit and 64-bit processes, how do you recommend doing this
without an unsigned long type ?
A 64-bit integer would not be a single-copy store for
32-bit processes, but a 32-bit integer would not be large
enough for 64-bit processes.
Would a
union {
uint32_t val32;
uint64_t val64;
} field;
be an acceptable option ? Then the kernel could use
one field or the other depending on the process bitness.
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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[PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-02-24 00:30 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Thomas Gleixner <tglx@linutronix.de> - 2016-02-24 12:20 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-02-24 18:20 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-02-26 00:40 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-02-26 18:50 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Peter Zijlstra <peterz@infradead.org> - 2016-02-25 11:00 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-02-25 18:00 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Peter Zijlstra <peterz@infradead.org> - 2016-02-25 18:10 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-02-25 18:20 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Peter Zijlstra <peterz@infradead.org> - 2016-02-26 12:40 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Thomas Gleixner <tglx@linutronix.de> - 2016-02-26 17:40 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-02-26 18:30 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Thomas Gleixner <tglx@linutronix.de> - 2016-02-26 19:10 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-02-26 21:30 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread "H. Peter Anvin" <hpa@zytor.com> - 2016-02-27 00:10 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-02-27 01:50 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread "H. Peter Anvin" <hpa@zytor.com> - 2016-02-27 07:30 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-02-27 15:20 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Peter Zijlstra <peterz@infradead.org> - 2016-02-27 16:00 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Linus Torvalds <torvalds@linux-foundation.org> - 2016-02-27 19:40 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread "H. Peter Anvin" <hpa@zytor.com> - 2016-02-27 20:10 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-02-28 01:00 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Linus Torvalds <torvalds@linux-foundation.org> - 2016-02-28 02:00 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-02-28 15:40 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Peter Zijlstra <peterz@infradead.org> - 2016-02-29 11:40 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-03-01 21:30 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Peter Zijlstra <peterz@infradead.org> - 2016-03-01 22:40 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Peter Zijlstra <peterz@infradead.org> - 2016-03-01 22:40 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread "H. Peter Anvin" <hpa@zytor.com> - 2016-03-01 23:00 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Peter Zijlstra <peterz@infradead.org> - 2016-03-02 11:40 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Peter Zijlstra <peterz@infradead.org> - 2016-02-29 11:40 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Arnd Bergmann <arnd@arndb.de> - 2016-02-29 11:50 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-02-29 13:50 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Arnd Bergmann <arnd@arndb.de> - 2016-02-29 14:20 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread "H. Peter Anvin" <hpa@zytor.com> - 2016-02-29 19:30 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Geert Uytterhoeven <geert@linux-m68k.org> - 2016-03-02 11:50 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread "H. Peter Anvin" <hpa@zytor.com> - 2016-03-01 19:30 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-03-01 19:50 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Geert Uytterhoeven <geert@linux-m68k.org> - 2016-02-28 14:10 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Linus Torvalds <torvalds@linux-foundation.org> - 2016-02-28 17:30 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread Peter Zijlstra <peterz@infradead.org> - 2016-02-29 11:10 +0100
Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread "H. Peter Anvin" <hpa@zytor.com> - 2016-02-27 16:10 +0100
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