Ken Moffat wrote:
On Sun, Jul 24, 2016 at 03:42:46PM +0200, Alain wrote:
Le 23/07/2016 05:07, Ken Moffat a écrit :
LOL. For vlc I have *never* managed to play a DVD correctly (they
play for some seconds, pause while the buffer is read from the DVD,
repeat) - I posted about that some time in the last 2 months after
discovering that even on my haswell i7 this was the case - until
then I had assumed my hardware was not good enough.
I have had the same problem here with VLC.
It was solved by configuring the kernel with :
Processor type and features :
Timer frequency : 1000Hz
CONFIG_HZ_1000=y
CONFIG_HZ=1000
Now, vlc can play video without pausing/buffering all the time.
Alain
Thanks, that is very interesting - I was starting to think that
perhaps there was something in the kernel config, but I could not
guess what it might be.
On the Sandy Bridge I'm using CONFIG_HZ_250=y, I suspect the
haswell is the same. This is not one of my urgent issues, might be
some time until I test it.
Checking, CONFIG_HZ=1000 seems to be the default, at least on my systems.
I have never set it directly that I recall, but I generally start on a
new system with 'make defconfig' and that sets it for me.
If someone starts with an old config file and runs 'make oldconfig', that
may account for propagating a poor setting for this parameter.
From the kernel help:
Allows the configuration of the timer frequency. It is customary to have
the timer interrupt run at 1000 Hz but 100 Hz may be more beneficial for
servers and NUMA systems that do not need to have a fast response for user
interaction and that may experience bus contention and cacheline bounces
as a result of timer interrupts. Note that the timer interrupt occurs on
each processor in an SMP environment leading to NR_CPUS * HZ number of
timer interrupts per second.
-- Bruce
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