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From: Robert William Fuller <hydrologiccycle@gmail.com>
To: Hans Verkuil <hverkuil@xs4all.nl>
Cc: "Németh Márton" <nm127@freemail.hu>,
	video4linux-list@redhat.com, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] video: simplify cx18_get_input() and	ivtv_get_input()
Date: Mon, 13 Oct 2008 17:40:48 -0400	[thread overview]
Message-ID: <48F3C060.2050302@gmail.com> (raw)
In-Reply-To: <200810132328.47170.hverkuil@xs4all.nl>

Hans Verkuil wrote:
> On Monday 13 October 2008 22:54:06 Németh Márton wrote:
>> From: Márton Németh <nm127@freemail.hu>
>>
>> The cx18_get_input() and ivtv_get_input() are called
>> once from the VIDIOC_ENUMINPUT ioctl() and once from
>> the *_log_status() functions. In the first case the
>> struct v4l2_input is already filled with zeros,
>> so doing this again is unnecessary.
> 
> And in the second case no one cares whether the struct is zeroed. And 
> the same situation is also true for ivtv_get_output().

Yeah, 'cos there's nothing better than uninitialized fields, like the 
recent report of a control that returns minimum and maximum values of 
zero, but a step-size of 9.  Why are we optimizing code paths that are 
not performance critical by uninitializing memory?

WARNING: multiple messages have this Message-ID (diff)
From: Robert William Fuller <hydrologiccycle@gmail.com>
To: Hans Verkuil <hverkuil@xs4all.nl>
Cc: video4linux-list@redhat.com, LKML <linux-kernel@vger.kernel.org>,
	"Németh Márton" <nm127@freemail.hu>
Subject: Re: [PATCH 2/2] video: simplify cx18_get_input() and	ivtv_get_input()
Date: Mon, 13 Oct 2008 17:40:48 -0400	[thread overview]
Message-ID: <48F3C060.2050302@gmail.com> (raw)
In-Reply-To: <200810132328.47170.hverkuil@xs4all.nl>

Hans Verkuil wrote:
> On Monday 13 October 2008 22:54:06 Németh Márton wrote:
>> From: Márton Németh <nm127@freemail.hu>
>>
>> The cx18_get_input() and ivtv_get_input() are called
>> once from the VIDIOC_ENUMINPUT ioctl() and once from
>> the *_log_status() functions. In the first case the
>> struct v4l2_input is already filled with zeros,
>> so doing this again is unnecessary.
> 
> And in the second case no one cares whether the struct is zeroed. And 
> the same situation is also true for ivtv_get_output().

Yeah, 'cos there's nothing better than uninitialized fields, like the 
recent report of a control that returns minimum and maximum values of 
zero, but a step-size of 9.  Why are we optimizing code paths that are 
not performance critical by uninitializing memory?

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  reply	other threads:[~2008-10-13 21:41 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-13 20:54 [PATCH 2/2] video: simplify cx18_get_input() and ivtv_get_input() Németh Márton
2008-10-13 21:28 ` Hans Verkuil
2008-10-13 21:28   ` Hans Verkuil
2008-10-13 21:40   ` Robert William Fuller [this message]
2008-10-13 21:40     ` Robert William Fuller
2008-10-13 21:49     ` Hans Verkuil
2008-10-13 21:49       ` [PATCH 2/2] video: simplify cx18_get_input() and ivtv_get_input () Hans Verkuil
2008-11-01 20:00       ` [PATCH 2/2] video: simplify cx18_get_input() and ivtv_get_input() Németh Márton

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