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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>
Cc:     carlos <carlos@redhat.com>, Peter Zijlstra <peterz@infradead.org>,
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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>
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Date:   Fri, 15 Jun 2018 07:07:01 +0200
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On 06/14/2018 02:27 PM, Pavel Machek wrote:

>>> Should we treat it the same way?  Always allocate it for each new thread
>>> and register it with the kernel?
>>
>> That would be an efficient way to do it, indeed. There is very little
>> performance overhead to have rseq registered for all threads, whether or
>> not they intend to run rseq critical sections.
> 
> People with slow / low memory machines would prefer not to see
> overhead they don't need...

I can try to get rid of the >500 byte per-thread area for the stub 
resolver.  That should compensate for the overhead introduced.

Thanks,
Florian