[LAU] Kernel 2.6.39 Re: Linux-audio-user Digest, Vol 52, Issue 33

[Ralf Mardorf]

On Wed, 2011-06-22 at 21:25 +0000,
linux-audio-user-request at lists.linuxaudio.org wrote:
> Message: 16
> Date: Wed, 22 Jun 2011 17:54:40 +0100
> From: Rui Nuno Capela
> Subject: Re: [LAU] Kernel 2.6.39
> To: linux-audio-user at lists.linuxaudio.org
> Message-ID: <4E021E50.80209 at rncbc.org>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> if you're about to  (aka. -rt) kernel the best 
> you can, with increased reliability on SCHED_FF scheduling (aka. 
> realtime scheduling, which is "bread & butter" for the whole jack 
> ecosystem) and provided you turn on the forced irq threads kernel
> boot 
> option (threadirqs) then PREEMPT is certainly the one to configure
> your 
> custom kernel.
> 
> beware, VOLUNTARY_PREEMPT (intended for general purpose desktops?)
> and 
> PREEMPT_NONE (certainly only for servers?) will just give you lousy, 
> xrun-prone system, with no resemblance whatsoever with a good old but 
> true -rt kernel ;)

Hi Rui :)

I used the config from the self-build kernel 2.6.33.9-rt31 and run
oldconfig only to configure 2.6.39. I didn't make music until now using
this kernel. Yes, I wish to "emulate" the PREEMPT_RT, since common
PREEMPT only kernels never did, what I needed.

What do I need to set?

$ cat config-2.6.39.1 | grep PREEMPT
CONFIG_TREE_PREEMPT_RCU=y
CONFIG_PREEMPT_RCU=y
CONFIG_PREEMPT_NOTIFIERS=y
# CONFIG_PREEMPT_NONE is not set
# CONFIG_PREEMPT_VOLUNTARY is not set
CONFIG_PREEMPT=y

IIUC this is correct?!

Cheers!

Ralf

PS: SCHED_FF?

$ cat config-2.6.39.1 | grep SCHED
CONFIG_HAVE_UNSTABLE_SCHED_CLOCK=y
# CONFIG_CGROUP_SCHED is not set
# CONFIG_SCHED_AUTOGROUP is not set
CONFIG_IOSCHED_NOOP=y
CONFIG_IOSCHED_DEADLINE=y
CONFIG_IOSCHED_CFQ=y
CONFIG_CFQ_GROUP_IOSCHED=y
CONFIG_DEFAULT_IOSCHED="cfq"
CONFIG_SCHED_OMIT_FRAME_POINTER=y
CONFIG_SCHED_SMT=y
CONFIG_SCHED_MC=y
CONFIG_SCHED_HRTICK=y
CONFIG_NET_SCHED=y
CONFIG_USB_EHCI_TT_NEWSCHED=y
$ cat config-2.6.39.1 | grep FF
CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y
CONFIG_CDROM_PKTCDVD_BUFFERS=8
CONFIG_BLK_DEV_IDEDMA_SFF=y
# CONFIG_BLK_DEV_OFFBOARD is not set
# Controllers with non-SFF native interface
CONFIG_ATA_SFF=y
# SFF controllers with custom DMA interface
# SATA SFF controllers with BMDMA
# PATA SFF controllers with BMDMA
# PIO-only SFF controllers
CONFIG_INPUT_FF_MEMLESS=m
CONFIG_JOYSTICK_XPAD_FF=y
CONFIG_IPMI_POWEROFF=m
# CONFIG_SPI_TOPCLIFF_PCH is not set
CONFIG_FRAMEBUFFER_CONSOLE=y
CONFIG_FRAMEBUFFER_CONSOLE_DETECT_PRIMARY=y
CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
CONFIG_DRAGONRISE_FF=y
# CONFIG_HID_EMS_FF is not set
CONFIG_LOGITECH_FF=y
CONFIG_LOGIRUMBLEPAD2_FF=y
# CONFIG_LOGIG940_FF is not set
# CONFIG_LOGIWII_FF is not set
CONFIG_PANTHERLORD_FF=y
CONFIG_GREENASIA_FF=y
CONFIG_SMARTJOYPLUS_FF=y
CONFIG_THRUSTMASTER_FF=y
CONFIG_ZEROPLUS_FF=y
# CONFIG_EDD_OFF is not set
CONFIG_AFFS_FS=m
CONFIG_JFFS2_FS=m
CONFIG_JFFS2_FS_DEBUG=0
CONFIG_JFFS2_FS_WRITEBUFFER=y
# CONFIG_JFFS2_FS_WBUF_VERIFY is not set
CONFIG_JFFS2_SUMMARY=y
CONFIG_JFFS2_FS_XATTR=y
CONFIG_JFFS2_FS_POSIX_ACL=y
CONFIG_JFFS2_FS_SECURITY=y
CONFIG_JFFS2_COMPRESSION_OPTIONS=y
CONFIG_JFFS2_ZLIB=y
CONFIG_JFFS2_LZO=y
CONFIG_JFFS2_RTIME=y
# CONFIG_JFFS2_RUBIN is not set
# CONFIG_JFFS2_CMODE_NONE is not set
CONFIG_JFFS2_CMODE_PRIORITY=y
# CONFIG_JFFS2_CMODE_SIZE is not set
# CONFIG_JFFS2_CMODE_FAVOURLZO is not set
CONFIG_RING_BUFFER=y
CONFIG_RING_BUFFER_ALLOW_SWAP=y