Message-ID: <4F01BC85.8050806@openwrt.org> (sfid-20120102_151752_851091_180FD67E)
Date: Mon, 02 Jan 2012 15:17:41 +0100
From: Felix Fietkau <nbd@openwrt.org>
MIME-Version: 1.0
To: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
CC: "John W. Linville" <linville@tuxdriver.com>,
	Jouni Malinen <jouni@qca.qualcomm.com>,
	linux-wireless@vger.kernel.org,
	Rodriguez Luis <rodrigue@qca.qualcomm.com>,
	Balasubramanian senthilkumar <senthilb@qca.qualcomm.com>,
	Vasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>,
	Rajkumar Manoharan <rmanohar@qca.qualcomm.com>,
	Vivek Natarajan <nataraja@qca.qualcomm.com>,
	m.sujith@gmail.com, ath9k-devel@lists.ath9k.org
Subject: Re: [RFC] ath9k_hw: make use of ar9003_calc_ptr_chksum
References: <1325509985-11720-1-git-send-email-mohammed@qca.qualcomm.com> <4F01B408.1080900@openwrt.org> <4F01B9CF.2020206@qca.qualcomm.com>
In-Reply-To: <4F01B9CF.2020206@qca.qualcomm.com>
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Sender: linux-wireless-owner@vger.kernel.org

On 2012-01-02 3:06 PM, Mohammed Shafi Shajakhan wrote:
> hi Felix,
> 
> 
> On Monday 02 January 2012 07:11 PM, Felix Fietkau wrote:
>> On 2012-01-02 2:13 PM, Mohammed Shafi Shajakhan wrote:
>>> From: Mohammed Shafi Shajakhan<mohammed@qca.qualcomm.com>
>>>
>>> make use of the already available function 'ar9003_calc_ptr_chksum'
>>> in 'ar9003_set_txdesc'
>>>
>>> Signed-off-by: Mohammed Shafi Shajakhan<mohammed@qca.qualcomm.com>
>> NACK. I intentionally did not use that function to avoid unnecessary
>> access to uncached memory (for performance reasons).
> 
> please explain how it effects the performance and will it cause a 
> significant impact
I don't have any exact numbers anymore, but it was visible enough in the
oprofile stats to justify a little functional duplication of code.
Eventually this duplication can go away if I can change the
ar9003_hw_set_desc_link function to incrementally fix up the checksum
instead of recalculating it, which would make the code even more efficient.

- Felix