From: Arnd Bergmann <arnd@arndb•de>
To: linuxppc-dev@lists•ozlabs.org
Cc: Pan Xinhui <xinhui@linux•vnet.ibm.com>,
Peter Zijlstra <peterz@infradead•org>,
Boqun Feng <boqun.feng@gmail•com>,
linux-kernel@vger•kernel.org, Paul Mackerras <paulus@samba•org>,
Thomas Gleixner <tglx@linutronix•de>
Subject: Re: [PATCH] powerpc: introduce {cmp}xchg for u8 and u16
Date: Sat, 16 Apr 2016 21:43:24 +0200 [thread overview]
Message-ID: <10192543.Wmc5qtLitu@wuerfel> (raw)
In-Reply-To: <570E2A45.9080702@linux.vnet.ibm.com>
On Wednesday 13 April 2016 19:15:17 Pan Xinhui wrote:
> Hello Peter,
>=20
> On 2016=E5=B9=B404=E6=9C=8812=E6=97=A5 22:30, Peter Zijlstra wrote:
> > On Sun, Apr 10, 2016 at 10:17:28PM +0800, Pan Xinhui wrote:
> >>
> >> On 2016=E5=B9=B404=E6=9C=8808=E6=97=A5 15:47, Peter Zijlstra wrote=
:
> >>> On Fri, Apr 08, 2016 at 02:41:46PM +0800, Pan Xinhui wrote:
> >>>> From: pan xinhui <xinhui.pan@linux•vnet.ibm.com>
> >>>>
> >>>> Implement xchg{u8,u16}{local,relaxed}, and
> >>>> cmpxchg{u8,u16}{,local,acquire,relaxed}.
> >>>>
> >>>> Atomic operation on 8-bit and 16-bit data type is supported from=
power7
> >>>
> >>> And yes I see nothing P7 specific here, this implementation is fo=
r
> >>> everything PPC64 afaict, no?
> >>>
> >> Hello Peter,
> >> =09No, it's not for every ppc. So yes, I need add #ifdef here. Tha=
nks for pointing it out.
> >> We might need a new config option and let it depend on POWER7/POWE=
R8_CPU or even POWER9...
> >=20
> > Right, I'm not sure if PPC has alternatives, but you could of cours=
e
> > runtime patch the code from emulated with 32bit ll/sc to native 8/1=
6bit
> > ll/sc if present on the current CPU if you have infrastructure for =
these
> > things.
> >=20
> seems interesting. I have no idea about how to runtime patch the code=
. I will try to learn that.
> If so, we need change {cmp}xchg into uninline functions?
I think you don't need to, see do_feature_fixups()/patch_feature_sectio=
n()
Note that an #ifdef by itself has to worry about any combination of
architectures, so in a kernel that has both POWER6 and POWER7 enabled,
you cannot call the POWER7-only function.
=09Arnd
next prev parent reply other threads:[~2016-04-16 19:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-08 6:41 [PATCH] powerpc: introduce {cmp}xchg for u8 and u16 Pan Xinhui
2016-04-08 7:47 ` Peter Zijlstra
2016-04-10 14:17 ` Pan Xinhui
2016-04-12 14:30 ` Peter Zijlstra
2016-04-13 11:15 ` Pan Xinhui
2016-04-13 15:53 ` Waiman Long
2016-04-14 8:31 ` Pan Xinhui
2016-04-16 19:43 ` Arnd Bergmann [this message]
2016-04-18 10:19 ` Pan Xinhui
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=10192543.Wmc5qtLitu@wuerfel \
--to=arnd@arndb$(echo .)de \
--cc=boqun.feng@gmail$(echo .)com \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=linuxppc-dev@lists$(echo .)ozlabs.org \
--cc=paulus@samba$(echo .)org \
--cc=peterz@infradead$(echo .)org \
--cc=tglx@linutronix$(echo .)de \
--cc=xinhui@linux$(echo .)vnet.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox