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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: Pavel Machek <pavel@ucw.cz>, carlos <carlos@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	libc-alpha <libc-alpha@sourceware.org>
Subject: Re: Restartable Sequences system call merged into Linux
Date: Thu, 14 Jun 2018 10:36:18 -0400 (EDT)	[thread overview]
Message-ID: <263666353.13077.1528986978282.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <48a0d905-2568-51b8-80c9-a20ecaa25f9b@redhat.com>

----- On Jun 14, 2018, at 10:00 AM, Florian Weimer fweimer@redhat.com wrote:

> On 06/14/2018 03:49 PM, Pavel Machek wrote:
>> Hi!
>> 
>>>>> - rseq_preempt(): on preemption, the scheduler sets the TIF_NOTIFY_RESUME thread
>>>>>    flag, so rseq_handle_notify_resume() can check whether it's in a rseq critical
>>>>>    section when returning to user-space,
>>>>> - rseq_signal_deliver(): on signal delivery, rseq_handle_notify_resume() checks
>>>>>    whether it's in a rseq critical section,
>>>>> - rseq_migrate: on migration, the scheduler sets TIF_NOTIFY_RESUME as well,
>>>>
>>>> Yes, this is not likely to be noticeable.
>>>>
>>>> But the proposal wanted to add a syscall to thread creation, right?
>>>> And I believe that may be noticeable.
>>>
>>> Fair point! Do we have a standard benchmark that would stress this ?
>> 
>> Web server performance benchmarks basically test clone() performance
>> in many cases.
> 
> Isn't that fork?  I expect that the rseq arena is inherited on fork and
> fork-type clone, otherwise it's going to be painful.

On fork or clone creating a new process, the rseq tls area is inherited
from the thread that does the fork syscall.

On creation of a new thread with clone, there is no such inheritance.

Thanks,

Mathieu

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

  reply	other threads:[~2018-06-14 14:36 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-11 19:49 Mathieu Desnoyers
2018-06-11 19:55 ` Florian Weimer
2018-06-11 20:04   ` Mathieu Desnoyers
2018-06-12 13:11     ` Florian Weimer
2018-06-12 16:31       ` Mathieu Desnoyers
2018-06-13  8:21         ` Florian Weimer
2018-06-14 12:27         ` Pavel Machek
2018-06-14 13:01           ` Mathieu Desnoyers
2018-06-14 13:25             ` Pavel Machek
2018-06-14 13:32               ` Florian Weimer
2018-06-14 13:46                 ` Mathieu Desnoyers
2018-06-15  5:10                   ` Florian Weimer
2018-06-15 17:44                     ` Mathieu Desnoyers
2018-06-14 13:38               ` Mathieu Desnoyers
2018-06-14 13:49                 ` Pavel Machek
2018-06-14 14:00                   ` Florian Weimer
2018-06-14 14:36                     ` Mathieu Desnoyers [this message]
2018-06-14 14:41                       ` Florian Weimer
2018-06-14 15:09                         ` Mathieu Desnoyers
2018-06-15  5:09             ` Florian Weimer
2018-06-15 17:50               ` Mathieu Desnoyers
2018-06-15  5:07           ` Florian Weimer
2018-06-13 11:48 ` Heiko Carstens
2018-06-13 16:14   ` Mathieu Desnoyers
2018-06-13 19:53     ` Mathieu Desnoyers

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