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From: Felix Fietkau <nbd@openwrt.org>
To: Peter Oh <poh@codeaurora.org>, ath10k@lists.infradead.org
Subject: Re: [PATCH 2/2] ath10k: do not use coherent memory for tx buffers
Date: Mon, 23 Nov 2015 19:34:53 +0100	[thread overview]
Message-ID: <56535C4D.1010703@openwrt.org> (raw)
In-Reply-To: <56535A23.3020804@codeaurora.org>

On 2015-11-23 19:25, Peter Oh wrote:
> 
> On 11/23/2015 10:02 AM, Sebastian Gottschall wrote:
>> Am 23.11.2015 um 18:25 schrieb Peter Oh:
>>> Hi,
>>>
>>> Have you measured the peak throughput?
>>> The pre-allocated coherent memory concept was introduced as once of 
>>> peak throughput improvement.
>>> IIRC, dma_map_single takes about 4 us on Cortex A7 and 
>>> dma_unmap_single also takes time to invalid cache.
>>> Please share your tput number before and after, so I don't need to 
>>> worry about performance degrade.
>> yes. and this concept fucks up the qualcom ipq806x platform (which has 
>> by default 2 QCA99XX cards). it does not work, since the preallocated 
>> concept allocates too much memory
> Can you specify the number that you're seeing?
> The tx buffer descriptor uses 56KB, so it would require 64KB x 2 slab 
> for 2 cards which is 128KB.
> Are you saying your system does not work because of this 128KB usage?
The reason might be the GFP_DMA flag, which is unnecessary.

- Felix

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  reply	other threads:[~2015-11-23 18:35 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-23 13:18 [PATCH 1/2] ath10k: do not use coherent memory for allocated device memory chunks Felix Fietkau
2015-11-23 13:18 ` Felix Fietkau
2015-11-23 13:18 ` [PATCH 2/2] ath10k: do not use coherent memory for tx buffers Felix Fietkau
2015-11-23 13:18   ` Felix Fietkau
2015-11-23 17:25   ` Peter Oh
2015-11-23 18:02     ` Sebastian Gottschall
2015-11-23 18:25       ` Peter Oh
2015-11-23 18:34         ` Felix Fietkau [this message]
2015-11-23 18:18     ` Felix Fietkau
2015-11-23 18:50       ` Peter Oh
2015-11-24 10:32         ` Felix Fietkau
2015-11-25 10:37           ` Kalle Valo
2015-11-30 10:29 ` [PATCH 1/2] ath10k: do not use coherent memory for allocated device memory chunks Kalle Valo
2015-11-30 10:29   ` Kalle Valo

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