From: andrew@lunn.ch (Andrew Lunn)
To: linux-arm-kernel@lists.infradead.org
Subject: I/O issues with writing to mtdblock devices on kirkwood
Date: Tue, 12 Jan 2016 02:19:04 +0100 [thread overview]
Message-ID: <20160112011904.GC7690@lunn.ch> (raw)
In-Reply-To: <20160112004749.GT6588@sirena.org.uk>
> Oh, right. This sounds like everything is working fine with SPI - that
> commit was supposed to improve throughput with single threaded workloads
> by avoiding pointless context switches and it seems it is in fact doing
> that. Most likely you are using a bitbanging SPI controller driver and
> that's causing lots of I/O wait states which is upsetting the scheduler
> but it's hard to be sure.
drivers/spi/spi-orion.c
Not bitbanging, but it is polled IO, not DMA.
> Possibly whatever SPI driver this system uses is doing something really
> rude (perhaps limited by the hardware), possibly it isn't using DMA when
> it should be, or possibly the scheduler just isn't doing a good job with
> the workload you're giving it.
When i played with this, i added a reschedule point at the end of the
drivers transfer_one_message() function, to see if that would help. It
did not, which is why i made a guess it has something to do with a
lock.
Andrew
next prev parent reply other threads:[~2016-01-12 1:19 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-21 12:24 I/O issues with writing to mtdblock devices on kirkwood Ian Campbell
2015-08-21 13:07 ` Andrew Lunn
2015-08-21 20:23 ` Ian Campbell
2015-09-05 21:08 ` Andrew Lunn
2015-09-06 12:11 ` Ian Campbell
2015-10-11 14:37 ` JM
2015-10-11 15:35 ` Andrew Lunn
2015-10-12 14:29 ` JM
2015-10-12 16:05 ` Rob J. Epping
2015-10-12 16:21 ` Andrew Lunn
2015-10-13 7:51 ` Ian Campbell
[not found] ` <5626B4DC.8000407@mcfarlanes.me>
[not found] ` <5627F4E8.3030907@mcfarlanes.me>
2015-10-21 21:11 ` Ian Campbell
2015-10-21 21:22 ` Iain McFarlane
2015-10-21 21:28 ` JM
2015-10-21 21:31 ` Iain McFarlane
2015-10-22 0:38 ` Andrew Lunn
2015-10-22 6:40 ` Ian Campbell
2015-10-22 6:40 ` Ian Campbell
2016-01-11 23:00 ` Martin Michlmayr
2016-01-11 23:22 ` Mark Brown
2016-01-11 23:43 ` Andrew Lunn
2016-01-12 1:21 ` Mark Brown
2016-01-12 0:07 ` Martin Michlmayr
2016-01-12 0:47 ` Mark Brown
2016-01-12 1:19 ` Andrew Lunn [this message]
2016-01-12 1:31 ` Mark Brown
2016-01-12 16:29 ` Arnd Bergmann
2016-01-12 18:02 ` Mark Brown
2016-01-12 21:49 ` Arnd Bergmann
2016-01-12 22:00 ` Mark Brown
2016-01-12 22:41 ` Arnd Bergmann
2016-01-13 11:42 ` Mark Brown
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160112011904.GC7690@lunn.ch \
--to=andrew@lunn.ch \
--cc=linux-arm-kernel@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).