From: Jean-Nicolas Graux <jean-nicolas.graux@st.com>
To: Vinod Koul <vkoul@kernel.org>
Cc: Linus Walleij <linus.walleij@linaro.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>
Subject: dmaengine: pl08x: be fair when re-assigning physical channel
Date: Mon, 25 Mar 2019 08:15:00 +0000 [thread overview]
Message-ID: <a123a5c1-c378-eba0-4e41-77c8c5eae58c@st.com> (raw)
On 3/25/19 6:13 AM, Vinod Koul wrote:
> On 04-03-19, 16:03, Jean-Nicolas Graux wrote:
>> Current way we find a waiting virtual channel for the next transfer
>> at the time one physical channel becomes free is not really fair.
>>
>> More in details, in case there is more than one channel waiting at a time,
>> by just going through the arrays of memcpy and slave channels and stopping
>> as soon as state match waiting state, channels with high indexes can be
>> penalized.
>>
>> Whenever dma engine is substantially overloaded so that we constantly
>> get several channels waiting, channels with highest indexes might not
>> be served for a substantial time which in the worse case, might hang
>> task that wait for dma transfer to complete.
>>
>> This patch makes physical channel re-assignment more fair by storing
>> time in jiffies when a channel is put in waiting state. Whenever a
>> physical channel has to be re-assigned, this time is used to select
>> channel that is waiting for the longest time.
> Applied, thanks
>
Hello Vinod, You are welcome.
Regards. Jean-Nicolas.
next reply other threads:[~2019-03-25 8:15 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-25 8:15 Jean-Nicolas Graux [this message]
-- strict thread matches above, loose matches on Subject: below --
2019-03-25 5:13 dmaengine: pl08x: be fair when re-assigning physical channel Vinod Koul
2019-03-04 15:03 Jean-Nicolas Graux
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