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Subject: Re: Restartable Sequences system call merged into Linux
To:     Pavel Machek <pavel@ucw.cz>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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        Boqun Feng <boqun.feng@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        libc-alpha <libc-alpha@sourceware.org>
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From:   Florian Weimer <fweimer@redhat.com>
Message-ID: <1110f198-88c2-544d-6836-f901b8e90f98@redhat.com>
Date:   Thu, 14 Jun 2018 15:32:17 +0200
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On 06/14/2018 03:25 PM, Pavel Machek wrote:

> But the proposal wanted to add a syscall to thread creation, right?
> And I believe that may be noticeable.

We already call set_robust_list, so we could just pass a larger area to 
that and the kernel could use it.  Then no additional system call would 
be needed in the common case (new kernel which recognizes the new area 
size).

But then we cannot use an initial-exec thread local variable for it 
(although the offset from the thread pointer will still be constant, of 
course).

Thanks,
Florian