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Date:      Thu, 9 Jun 2016 11:29:22 -0300
From:      Luiz Otavio O Souza <lists.br@gmail.com>
To:        Warner Losh <wlosh@bsdimp.com>
Cc:        Gergely Imreh <imrehg@gmail.com>, FreeBSD ARM <freebsd-arm@freebsd.org>
Subject:   Re: RPi2 i/o blocking and SD card performance
Message-ID:  <CAB=2f8zdoaiXU0n2ps7%2Bbdmc=qoQBZmQydjhBh%2BhA-UKHJBaew@mail.gmail.com>
In-Reply-To: <6406AECE-0153-494F-88EE-E58C8357FC1B@bsdimp.com>
References:  <CAJ3iQcoc5nVSFz3JKMG_Y9Q9k4PFizmp2rf3vfA7nv=u_12nBQ@mail.gmail.com> <6406AECE-0153-494F-88EE-E58C8357FC1B@bsdimp.com>

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On 9 June 2016 at 10:55, Warner Losh wrote:
>
>> On Jun 9, 2016, at 5:37 AM, Gergely Imreh wrote:
>>
>> Hi,
>>
>> I've been testing FreeBSD 11.0-CURRENT on a RaspberryPi2. I'm relatively
>> new to FreeBSD, and wondering if there's any advice for improving the
>> performance a bit.
>>
>> First, it looks like there's a lot of i/o blocking behaviour going on. For
>> example running MediaWiki on the board, if I compile any ports, the site
>> itself is pretty much unusable (the PHP scripts time out even with 180s
>> timeouts). The strangest thing is that the CPU usage is not at 100% all the
>> way, can be that all 4 cores are ~99% idle, and still everything goes very
>> slow. Once the ports compilation or any other i/o-related task is finished,
>> it's snappy again.

Yeah, the DMA support is suboptimal and only does one block at time,
this is on my TODO list for a while.

>>
>> Any idea why it could be to have such big latency/lag even though the CPU
>> is idle? Is there anything I could test?

Not at this moment, sorry.

Luiz



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