Commit 40fcfc87 authored by Alan Cox's avatar Alan Cox Committed by Linus Torvalds
Browse files

[PATCH] HZ: 300Hz support 



Fix two things.  Firstly the unit is "Hz" not "HZ".  Secondly it is useful
to have 300Hz support when doing multimedia work.  250 is fine for us in
Europe but the US frame rate is 30fps (29.99 blah for pedants).  300 gives
us a tick divisible by both 25 and 30, and for interlace work 50 and 60.
It's also giving similar performance to 250Hz.

I'd argue we should remove 250 and add 300, but that might be excess
disruption for now.

Signed-off-by: default avatarAlan Cox <alan@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent d5abe669

kernel/Kconfig.hz

+15 −5
Original line number Diff line number Diff line
@@ -7,7 +7,7 @@ choice 
	default HZ_250

	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

	 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.
@@ -19,21 +19,30 @@ choice 
	config HZ_100

		bool "100 HZ"

	help

	  100 HZ is a typical choice for servers, SMP and NUMA systems

	  100 Hz is a typical choice for servers, SMP and NUMA systems

	  with lots of processors that may show reduced performance if

	  too many timer interrupts are occurring.



	config HZ_250

		bool "250 HZ"

	help

	 250 HZ is a good compromise choice allowing server performance

	 250 Hz is a good compromise choice allowing server performance

	 while also showing good interactive responsiveness even

	 on SMP and NUMA systems.

	 on SMP and NUMA systems. If you are going to be using NTSC video

	 or multimedia, selected 300Hz instead.



	config HZ_300

		bool "300 HZ"

	help

	 300 Hz is a good compromise choice allowing server performance

	 while also showing good interactive responsiveness even

	 on SMP and NUMA systems and exactly dividing by both PAL and

	 NTSC frame rates for video and multimedia work.



	config HZ_1000

		bool "1000 HZ"

	help

	 1000 HZ is the preferred choice for desktop systems and other

	 1000 Hz is the preferred choice for desktop systems and other

	 systems requiring fast interactive responses to events.



endchoice
@@ -42,5 +51,6 @@ config HZ 
	int

	default 100 if HZ_100

	default 250 if HZ_250

	default 300 if HZ_300

	default 1000 if HZ_1000

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