From: Torvald Riegel <triegel@redhat.com>
To: Chris Metcalf <cmetcalf@mellanox.com>
Cc: David Miller <davem@davemloft.net>,
carlos@redhat.com, adhemerval.zanella@linaro.org,
andreas@gaisler.com, libc-alpha@sourceware.org,
software@gaisler.com
Subject: Re: Remove sparcv8 support
Date: Thu, 10 Nov 2016 23:38:00 -0000 [thread overview]
Message-ID: <1478821111.7146.1016.camel@localhost.localdomain> (raw)
In-Reply-To: <17b6735b-7376-bb70-5b70-c53fa6fb2c87@mellanox.com>
On Thu, 2016-11-10 at 13:22 -0500, Chris Metcalf wrote:
> On 11/10/2016 12:08 PM, Torvald Riegel wrote:
> > Looking at tile's atomic-machine.h files again, it seems we're not
> > actually enforcing that atomic stores are atomic wrt. the CAS
> > implementation in the kernel.
> > The default implementation for atomic_store_relaxed in include/atomic.h
> > does a plain memory store instead of falling back to exchange. This is
> > the right approach by default, I think, because that's what
> > pre-C11-concurrency code in glibc does (ie, there's no abstraction for
> > an atomic store at all, and plain memory accesses are used).
> >
> > However, if we emulate CAS with locks or such in the kernel, atomic
> > stores need to synchronize with the CAS. This would mean that all archs
> > such as tile or sparc that do that have to define atomic_store_relaxed
> > to fix this (at least for code converted to using C11 atomics, all
> > nonconverted code might still do the wrong thing).
>
> Note that our mainstream tilegx architecture has full atomic support, so
> this is only applicable to the older tilepro architecture.
LGTM, thanks.
next prev parent reply other threads:[~2016-11-10 23:38 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-20 19:47 Adhemerval Zanella
2016-10-20 20:56 ` David Miller
2016-10-21 9:02 ` Andreas Larsson
2016-10-21 13:13 ` Adhemerval Zanella
2016-10-21 15:03 ` David Miller
2016-10-24 17:14 ` Torvald Riegel
2016-10-24 17:25 ` Torvald Riegel
2016-10-24 17:43 ` Adhemerval Zanella
2016-10-25 14:34 ` Andreas Larsson
2016-10-25 14:45 ` Adhemerval Zanella
2016-10-26 14:46 ` Andreas Larsson
2016-10-26 18:03 ` Adhemerval Zanella
2016-10-26 18:47 ` David Miller
2016-10-26 19:39 ` Adhemerval Zanella
2016-10-27 10:54 ` Torvald Riegel
2016-10-27 14:36 ` Carlos O'Donell
2016-11-07 16:38 ` David Miller
2016-11-07 21:21 ` Sam Ravnborg
2016-11-08 1:06 ` David Miller
2016-11-09 5:49 ` Sam Ravnborg
2016-11-10 23:33 ` David Miller
2016-11-09 17:08 ` Torvald Riegel
2016-11-09 17:16 ` David Miller
2016-11-10 5:05 ` Torvald Riegel
2016-11-10 16:41 ` Chris Metcalf
2016-11-10 17:08 ` Torvald Riegel
2016-11-10 18:22 ` Chris Metcalf
2016-11-10 23:38 ` Torvald Riegel [this message]
2016-10-27 10:38 ` Torvald Riegel
2016-11-01 15:27 ` Andreas Larsson
2016-10-25 14:34 ` Andreas Larsson
2016-10-25 16:22 ` Torvald Riegel
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