linux-kernel - Re: [RFC PATCH 1/1] cleanup: use bool as return type for rwsem_is

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Date:	Fri, 6 Jun 2014 14:52:40 -0400
From:	Pranith Kumar <pranith@...ech.edu>
To:	Davidlohr Bueso <davidlohr@...com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	LKML <linux-kernel@...r.kernel.org>, tim.c.chen@...ux.intel.com,
	mingo@...hat.com
Subject: Re: [RFC PATCH 1/1] cleanup: use bool as return type for rwsem_is_locked

On Fri, Jun 6, 2014 at 2:41 PM, Davidlohr Bueso <davidlohr@...com> wrote:
> On Fri, 2014-06-06 at 19:56 +0200, Peter Zijlstra wrote:
>> On Fri, Jun 06, 2014 at 01:53:01PM -0400, Pranith Kumar wrote:
>> > On Fri, Jun 6, 2014 at 3:35 AM, Peter Zijlstra <peterz@...radead.org> wrote:
>> > >
>> > > Now in general, I don't particularly like such superfluous changes, so
>> > > unless you can show that GCC actually generates better code, I'd prefer
>> > > to keep things as they are.
>> >
>> > Fixed and checked the assembly. It saves us 2 bytes of code, not much. I am not sure if that is worth it :(
>>
>> still 2 bytes, so sure.
>>
>> Which gcc did you use and what arch did you build? That might be useful
>> info for the changelog.
>
> Yeah, please attach the output of 'size kernel/locking/rwsem.o' for both
> before and after. I think there's similar opportunity in other locking
> code as well.
>

Ok. Here is the data.

size kernel/locking/rwsem-spinlock.o

Before change to bool:

   text       data        bss        dec        hex
   1336          0          0       1336        538

After change to bool:

   text       data        bss        dec        hex
   1334          0          0       1334        536

-- 
Pranith
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