linux-kernel - Re: Restartable Sequences system call merged into Linux

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Message-ID: <608bdd59-9ddb-bf68-0127-a0c54002b582@redhat.com>
Date:   Fri, 15 Jun 2018 07:07:01 +0200
From:   Florian Weimer <fweimer@...hat.com>
To:     Pavel Machek <pavel@....cz>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc:     carlos <carlos@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        libc-alpha <libc-alpha@...rceware.org>
Subject: Re: Restartable Sequences system call merged into Linux

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