From: Olof Johansson <olof@lixom.net>
To: Kyle McMartin <kyle@mcmartin.ca>
Cc: grundler@parisc-linux.org, linux-kernel@vger.kernel.org,
kyle@parisc-linux.org, linuxppc-dev@ozlabs.org,
lethal@linux-sh.org, Paul Mackerras <paulus@samba.org>,
akpm@linux-foundation.org
Subject: Re: [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON()
Date: Thu, 11 Oct 2007 21:41:43 -0500 [thread overview]
Message-ID: <20071012024143.GA20475@lixom.net> (raw)
In-Reply-To: <20071012020419.GB19268@fattire.cabal.ca>
On Thu, Oct 11, 2007 at 10:04:19PM -0400, Kyle McMartin wrote:
> On Fri, Oct 12, 2007 at 11:23:39AM +1000, Paul Mackerras wrote:
> > Olof Johansson writes:
> >
> > > Not using the ppc-specific WARN_ON/BUG_ON constructs actually saves about
> > > 4K text on a ppc64_defconfig. The main reason seems to be that prepping
> > > the arguments to the conditional trap instructions is more work than
> > > just doing a compare and branch.
> >
> > It might be more instructions but it takes fewer cycles, I would
> > expect. Do you have the actual instruction sequences to compare?
> >
>
> I really hope WARN_ON/BUG_ON aren't hotpaths on powerpc. ;-)
Not the taken branch of them, no. :) But making it past them as fast
as possible when they're not tripping is always good.
-Olof
WARNING: multiple messages have this Message-ID (diff)
From: Olof Johansson <olof@lixom.net>
To: Kyle McMartin <kyle@mcmartin.ca>
Cc: Paul Mackerras <paulus@samba.org>,
linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
lethal@linux-sh.org, kyle@parisc-linux.org,
grundler@parisc-linux.org, linuxppc-dev@ozlabs.org
Subject: Re: [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON()
Date: Thu, 11 Oct 2007 21:41:43 -0500 [thread overview]
Message-ID: <20071012024143.GA20475@lixom.net> (raw)
In-Reply-To: <20071012020419.GB19268@fattire.cabal.ca>
On Thu, Oct 11, 2007 at 10:04:19PM -0400, Kyle McMartin wrote:
> On Fri, Oct 12, 2007 at 11:23:39AM +1000, Paul Mackerras wrote:
> > Olof Johansson writes:
> >
> > > Not using the ppc-specific WARN_ON/BUG_ON constructs actually saves about
> > > 4K text on a ppc64_defconfig. The main reason seems to be that prepping
> > > the arguments to the conditional trap instructions is more work than
> > > just doing a compare and branch.
> >
> > It might be more instructions but it takes fewer cycles, I would
> > expect. Do you have the actual instruction sequences to compare?
> >
>
> I really hope WARN_ON/BUG_ON aren't hotpaths on powerpc. ;-)
Not the taken branch of them, no. :) But making it past them as fast
as possible when they're not tripping is always good.
-Olof
next prev parent reply other threads:[~2007-10-12 2:36 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-11 17:12 [PATCH 1/2] bug.h: Introduce HAVE_ARCH_WARN Olof Johansson
2007-10-11 17:12 ` Olof Johansson
2007-10-11 17:14 ` [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON() Olof Johansson
2007-10-11 17:14 ` Olof Johansson
2007-10-11 19:55 ` Scott Wood
2007-10-11 19:55 ` Scott Wood
2007-10-12 1:23 ` Paul Mackerras
2007-10-12 1:23 ` Paul Mackerras
2007-10-12 2:04 ` Kyle McMartin
2007-10-12 2:04 ` Kyle McMartin
2007-10-12 2:41 ` Olof Johansson [this message]
2007-10-12 2:41 ` Olof Johansson
2007-10-12 2:40 ` Olof Johansson
2007-10-19 2:03 ` [PATCH v2] [2/2] " Olof Johansson
2007-10-19 2:03 ` Olof Johansson
2007-10-11 17:20 ` [PATCH 1/2] bug.h: Introduce HAVE_ARCH_WARN Kyle McMartin
2007-10-12 2:53 ` Paul Mundt
2007-10-18 22:17 ` Andrew Morton
2007-10-18 22:34 ` Olof Johansson
2007-10-19 2:03 ` [PATCH v2] [1/2] bug.h: Remove HAVE_ARCH_BUG.* / HAVE_ARCH_WARN.* Olof Johansson
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