From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: linux-kernel@vger.kernel.org, npiggin@gmail.com,
Paul Mackerras <paulus@samba.org>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2] powerpc/uaccess: Use flexible addressing with __put_user()/__get_user()
Date: Wed, 12 Aug 2020 14:30:32 -0500 [thread overview]
Message-ID: <20200812193032.GU6753@gate.crashing.org> (raw)
In-Reply-To: <0b63e2b8-a134-9a50-2106-8ff110cf9a31@csgroup.eu>
On Wed, Aug 12, 2020 at 02:32:51PM +0200, Christophe Leroy wrote:
> Anyway, it seems that GCC doesn't make much use of the "m<>" and the
> pre-update form.
GCC does not use update form outside of inner loops much. Did you
expect anything else?
> Most of the benefit of flexible addressing seems to be
> achieved with patch 1 ie without the "m<>" constraint and update form.
Yes.
Segher
WARNING: multiple messages have this Message-ID (diff)
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
npiggin@gmail.com, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] powerpc/uaccess: Use flexible addressing with __put_user()/__get_user()
Date: Wed, 12 Aug 2020 14:30:32 -0500 [thread overview]
Message-ID: <20200812193032.GU6753@gate.crashing.org> (raw)
In-Reply-To: <0b63e2b8-a134-9a50-2106-8ff110cf9a31@csgroup.eu>
On Wed, Aug 12, 2020 at 02:32:51PM +0200, Christophe Leroy wrote:
> Anyway, it seems that GCC doesn't make much use of the "m<>" and the
> pre-update form.
GCC does not use update form outside of inner loops much. Did you
expect anything else?
> Most of the benefit of flexible addressing seems to be
> achieved with patch 1 ie without the "m<>" constraint and update form.
Yes.
Segher
next prev parent reply other threads:[~2020-08-12 19:33 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-16 12:39 [PATCH v2] powerpc/uaccess: Use flexible addressing with __put_user()/__get_user() Christophe Leroy
2020-04-16 12:39 ` Christophe Leroy
2020-06-29 6:52 ` Christophe Leroy
2020-06-29 11:27 ` Michael Ellerman
2020-06-30 1:19 ` Michael Ellerman
2020-06-30 14:55 ` Christophe Leroy
2020-06-30 16:33 ` Segher Boessenkool
2020-06-30 16:33 ` Segher Boessenkool
2020-06-30 17:02 ` Christophe Leroy
2020-06-30 17:31 ` Christophe Leroy
2020-06-30 18:53 ` Christophe Leroy
2020-06-30 18:53 ` Christophe Leroy
2020-06-30 21:18 ` Segher Boessenkool
2020-06-30 21:18 ` Segher Boessenkool
2020-07-01 7:05 ` Christophe Leroy
2020-07-01 7:05 ` Christophe Leroy
2020-07-07 12:44 ` Christophe Leroy
2020-07-07 19:02 ` Christophe Leroy
2020-07-08 4:49 ` Christophe Leroy
2020-08-12 12:32 ` Christophe Leroy
2020-08-12 19:30 ` Segher Boessenkool [this message]
2020-08-12 19:30 ` Segher Boessenkool
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