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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: K Prateek Nayak <kprateek.nayak@amd.com>,
	Prakash Sangappa <prakash.sangappa@oracle.com>,
	Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Madadi Vineeth Reddy <vineethr@linux.ibm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Arnd Bergmann <arnd@arndb.de>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Subject: Re: [patch 02/12] rseq: Add fields and constants for time slice extension
Date: Mon, 22 Sep 2025 09:57:30 -0400	[thread overview]
Message-ID: <fd5abd03-0198-44cb-8cfd-b0d2cf44a35d@efficios.com> (raw)
In-Reply-To: <228e2fb7-e141-462c-8796-3cf78aa01902@amd.com>

On 2025-09-22 01:57, K Prateek Nayak wrote:
> Hello Prakash,
> 
> On 9/22/2025 10:58 AM, Prakash Sangappa wrote:
>> With use of a new structure member for slice control, could there be discrepancy
>> with rseq structure size(older version) registered by libc?  In that case the application
>> may  not be able to use slice extension feature unless Libc’s use of rseq is disabled.
> 
> In this case, wouldn't GLIBC's rseq registration fail if presumed
> __rseq_size is smaller than the "struct rseq" size?

The registered rseq size cannot be smaller than 32 bytes, else
registration is refused by the system call (-EINVAL).

The new slice extension fields would fit within those 32 bytes,
so it should always work.

Thanks,

Mathieu



-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com

  reply	other threads:[~2025-09-22 13:57 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-08 22:59 [patch 00/12] rseq: Implement time slice extension mechanism Thomas Gleixner
2025-09-08 22:59 ` [patch 01/12] sched: Provide and use set_need_resched_current() Thomas Gleixner
2025-09-08 22:59 ` [patch 02/12] rseq: Add fields and constants for time slice extension Thomas Gleixner
2025-09-09  0:04   ` Randy Dunlap
2025-09-11 15:41   ` Mathieu Desnoyers
2025-09-11 15:49     ` Mathieu Desnoyers
2025-09-22  5:28   ` Prakash Sangappa
2025-09-22  5:57     ` K Prateek Nayak
2025-09-22 13:57       ` Mathieu Desnoyers [this message]
2025-09-22 13:55     ` Mathieu Desnoyers
2025-09-23  0:57       ` Prakash Sangappa
2025-09-08 22:59 ` [patch 03/12] rseq: Provide static branch for time slice extensions Thomas Gleixner
2025-09-09  3:10   ` K Prateek Nayak
2025-09-09  4:11     ` Randy Dunlap
2025-09-09 12:12       ` Thomas Gleixner
2025-09-09 16:01         ` Randy Dunlap
2025-09-11 15:42   ` Mathieu Desnoyers
2025-09-08 22:59 ` [patch 04/12] rseq: Add statistics " Thomas Gleixner
2025-09-11 15:43   ` Mathieu Desnoyers
2025-09-08 22:59 ` [patch 05/12] rseq: Add prctl() to enable " Thomas Gleixner
2025-09-11 15:50   ` Mathieu Desnoyers
2025-09-11 16:52     ` K Prateek Nayak
2025-09-11 17:18       ` Mathieu Desnoyers
2025-09-08 23:00 ` [patch 06/12] rseq: Implement sys_rseq_slice_yield() Thomas Gleixner
2025-09-09  9:52   ` K Prateek Nayak
2025-09-09 12:23     ` Thomas Gleixner
2025-09-10 11:15   ` K Prateek Nayak
2025-09-08 23:00 ` [patch 07/12] rseq: Implement syscall entry work for time slice extensions Thomas Gleixner
2025-09-10  5:22   ` K Prateek Nayak
2025-09-10  7:49     ` Thomas Gleixner
2025-09-08 23:00 ` [patch 08/12] rseq: Implement time slice extension enforcement timer Thomas Gleixner
2025-09-10 11:20   ` K Prateek Nayak
2025-09-08 23:00 ` [patch 09/12] rseq: Reset slice extension when scheduled Thomas Gleixner
2025-09-08 23:00 ` [patch 10/12] rseq: Implement rseq_grant_slice_extension() Thomas Gleixner
2025-09-09  8:14   ` K Prateek Nayak
2025-09-09 12:16     ` Thomas Gleixner
2025-09-08 23:00 ` [patch 11/12] entry: Hook up rseq time slice extension Thomas Gleixner
2025-09-08 23:00 ` [patch 12/12] selftests/rseq: Implement time slice extension test Thomas Gleixner
2025-09-10 11:23   ` K Prateek Nayak
2025-09-09 12:37 ` [patch 00/12] rseq: Implement time slice extension mechanism Thomas Gleixner
2025-09-10  4:42   ` K Prateek Nayak
2025-09-10 11:28 ` K Prateek Nayak
2025-09-10 14:50   ` Thomas Gleixner
2025-09-11  3:03     ` K Prateek Nayak
2025-09-11  7:36       ` Prakash Sangappa
2025-09-11 15:27 ` Mathieu Desnoyers
2025-09-11 20:18   ` Thomas Gleixner
2025-09-12 12:33     ` Mathieu Desnoyers
2025-09-12 16:31       ` Thomas Gleixner
2025-09-12 19:26         ` Mathieu Desnoyers
2025-09-13 13:02           ` Thomas Gleixner
2025-09-19 17:30             ` Prakash Sangappa
2025-09-22 14:09               ` Mathieu Desnoyers
2025-09-23  1:01                 ` Prakash Sangappa

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