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Re: [PATCH 2/5] glibc: sched_getcpu(): use rseq cpu_id TLS on Linux (v2)
- From: Mathieu Desnoyers <mathieu dot desnoyers at efficios dot com>
- To: Szabolcs Nagy <Szabolcs dot Nagy at arm dot com>
- Cc: carlos <carlos at redhat dot com>, nd <nd at arm dot com>, Florian Weimer <fweimer at redhat dot com>, Joseph Myers <joseph at codesourcery dot com>, libc-alpha <libc-alpha at sourceware dot org>, Thomas Gleixner <tglx at linutronix dot de>, Ben Maurer <bmaurer at fb dot com>, Peter Zijlstra <peterz at infradead dot org>, "Paul E. McKenney" <paulmck at linux dot vnet dot ibm dot com>, Boqun Feng <boqun dot feng at gmail dot com>, Will Deacon <Will dot Deacon at arm dot com>, Dave Watson <davejwatson at fb dot com>, Paul Turner <pjt at google dot com>, linux-kernel <linux-kernel at vger dot kernel dot org>, linux-api <linux-api at vger dot kernel dot org>
- Date: Thu, 18 Apr 2019 11:45:25 -0400 (EDT)
- Subject: Re: [PATCH 2/5] glibc: sched_getcpu(): use rseq cpu_id TLS on Linux (v2)
- Dkim-filter: OpenDKIM Filter v2.10.3 mail.efficios.com DD59C18CBC8
- References: <20190416173216.9028-1-mathieu.desnoyers@efficios.com> <20190416173216.9028-3-mathieu.desnoyers@efficios.com> <c9c53d4b-ed9b-f2d9-60b0-e5e805de0324@arm.com>
----- On Apr 18, 2019, at 11:33 AM, Szabolcs Nagy Szabolcs.Nagy@arm.com wrote:
> On 16/04/2019 18:32, Mathieu Desnoyers wrote:
>> --- a/sysdeps/unix/sysv/linux/sched_getcpu.c
>> +++ b/sysdeps/unix/sysv/linux/sched_getcpu.c
>> @@ -37,3 +37,26 @@ sched_getcpu (void)
>> return -1;
>> #endif
>> }
>> +
>> +#ifdef __NR_rseq
>> +#include <sys/rseq.h>
>> +#endif
>> +
>> +#if defined __NR_rseq && defined RSEQ_SIG
>> +extern __attribute__ ((tls_model ("initial-exec")))
>> +__thread volatile struct rseq __rseq_abi;
>
> i'd expect sys/rseq.h to provide this declaration.
And it actually does! Will remove this duplicate.
Thanks,
Mathieu
>
>> +
>> +int
>> +sched_getcpu (void)
>> +{
>> + int cpu_id = __rseq_abi.cpu_id;
>> +
>> + return cpu_id >= 0 ? cpu_id : vsyscall_sched_getcpu ();
>> +}
>> +#else
>> +int
>> +sched_getcpu (void)
>> +{
>> + return vsyscall_sched_getcpu ();
>> +}
>> +#endif
>> -- 2.17.1
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com