lkml.org 
[lkml]   [2016]   [Dec]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] stmmac: disable tx coalescing
On Sun 2016-12-11 14:31:13, David Miller wrote:
> From: Pavel Machek <pavel@ucw.cz>
> Date: Sun, 11 Dec 2016 20:07:50 +0100
>
> > David, ping? Can I get you to apply this one?
> >
> > As you noticed, tx coalescing is completely broken in that driver, and
> > not easy to repair. This is simplest way to disable it. It can still
> > be re-enabled from userspace, so code can be fixed in future.
>
> Sorry I'm not applying this, I want you and the driver maintainer
> to reach a real solution.

This is what you said about this driver:

# > 4.9-rc6 still has the delays. With the
# >
# > #define STMMAC_COAL_TX_TIMER 1000
# > #define STMMAC_TX_MAX_FRAMES 2
# >
# > settings, delays go away, and driver still works. (It fails fairly
# > fast in 4.4). Good news. But the question still is: what is going on
# > there?
#
# 256 packets looks way too large for being a trigger for aborting the
# TX coalescing timer.
#
# Looking more deeply into this, the driver is using non-highres timers
# to implement the TX coalescing. This simply cannot work.
#
# 1 HZ, which is the lowest granularity of non-highres timers in the
# kernel, is variable as well as already too large of a delay for
# effective TX coalescing.
#
# I seriously think that the TX coalescing support should be ripped out
# or disabled entirely until it is implemented properly in this driver.

I'm doing just that -- disabling it entirely until it is done
properly.

Unfortunately, maintainer does not think delays are huge problem. So I
need your help here.

Thanks,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2016-12-11 20:58    [W:0.066 / U:2.800 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site