>Ideally, the flushing algorithm would be tightly coupled to the wakeup
>time calculation. update is quite simplistic, and also isn't part of the
update can run every msec but the number of dirty buffer flushed/sec has
to remain the same. That doesn't happen due the current flushtime design
but this is a completly different issue (and I just spotted and fixed it
some time ago), you don't need to kill update if there's a bug somewhere
else.
Even if you run update very frequently you won't flush more data to disk.
The only point of update is trying to be friendly under crash. Nothing
more.
Really please try out:
ftp://e-mind.com/pub/andrea/kernel/2.2.8_andrea1.bz2
or
ftp://e-mind.com/pub/andrea/kernel/2.3.1_andrea1.bz2
and do some test under heavy load.
>Having an atime means that a system (on a laptop) that reads files, but
>doesn't write to any, will still want to wake up the disk. Some people
With my current tree having atime or not is really a minor issue. I know
it's an issue with the old flushtime handling. Here I have atime set but:
Script started on Fri May 14 12:40:37 1999
andrea@laser:~$ /usr/bin/time cvs diff -u /usr/src/linux >/dev/null
cvs diff: Diffing /usr/src/linux
cvs diff: Diffing /usr/src/linux/Documentation
cvs diff: Diffing /usr/src/linux/Documentation/arm
cvs diff: Diffing /usr/src/linux/Documentation/arm/nwfpe
cvs diff: Diffing /usr/src/linux/Documentation/cdrom
cvs diff: Diffing /usr/src/linux/Documentation/fb
cvs diff: Diffing /usr/src/linux/Documentation/filesystems
cvs diff: Diffing /usr/src/linux/Documentation/i386
cvs diff: Diffing /usr/src/linux/Documentation/isdn
cvs diff: Diffing /usr/src/linux/Documentation/kbuild
cvs diff: Diffing /usr/src/linux/Documentation/m68k
cvs diff: Diffing /usr/src/linux/Documentation/networking
cvs diff: Diffing /usr/src/linux/Documentation/networking/ip_masq
cvs diff: Diffing /usr/src/linux/Documentation/powerpc
cvs diff: Diffing /usr/src/linux/Documentation/sound
cvs diff: Diffing /usr/src/linux/Documentation/sysctl
cvs diff: Diffing /usr/src/linux/Documentation/video4linux
cvs diff: Diffing /usr/src/linux/Documentation/video4linux/bttv
cvs diff: Diffing /usr/src/linux/arch
cvs diff: Diffing /usr/src/linux/arch/alpha
cvs diff: Diffing /usr/src/linux/arch/alpha/boot
cvs diff: Diffing /usr/src/linux/arch/alpha/boot/tools
cvs diff: Diffing /usr/src/linux/arch/alpha/kernel
cvs diff: Diffing /usr/src/linux/arch/alpha/lib
cvs diff: Diffing /usr/src/linux/arch/alpha/math-emu
cvs diff: Diffing /usr/src/linux/arch/alpha/mm
cvs diff: Diffing /usr/src/linux/arch/arm
cvs diff: Diffing /usr/src/linux/arch/arm/boot
cvs diff: Diffing /usr/src/linux/arch/arm/boot/compressed
cvs diff: Diffing /usr/src/linux/arch/arm/kernel
cvs diff: Diffing /usr/src/linux/arch/arm/lib
cvs diff: Diffing /usr/src/linux/arch/arm/mm
cvs diff: Diffing /usr/src/linux/arch/i386
cvs diff: Diffing /usr/src/linux/arch/i386/boot
cvs diff: Diffing /usr/src/linux/arch/i386/boot/compressed
cvs diff: Diffing /usr/src/linux/arch/i386/boot/tools
cvs diff: Diffing /usr/src/linux/arch/i386/kernel
cvs diff: Diffing /usr/src/linux/arch/i386/kernel/debug
cvs diff: Diffing /usr/src/linux/arch/i386/lib
cvs diff: Diffing /usr/src/linux/arch/i386/math-emu
cvs diff: Diffing /usr/src/linux/arch/i386/mm
cvs diff: Diffing /usr/src/linux/arch/m68k
cvs diff: Diffing /usr/src/linux/arch/m68k/amiga
cvs diff: Diffing /usr/src/linux/arch/m68k/apollo
cvs diff: Diffing /usr/src/linux/arch/m68k/atari
cvs diff: Diffing /usr/src/linux/arch/m68k/bvme6000
cvs diff: Diffing /usr/src/linux/arch/m68k/fpsp040
cvs diff: Diffing /usr/src/linux/arch/m68k/hp300
cvs diff: Diffing /usr/src/linux/arch/m68k/ifpsp060
cvs diff: Diffing /usr/src/linux/arch/m68k/kernel
cvs diff: Diffing /usr/src/linux/arch/m68k/lib
cvs diff: Diffing /usr/src/linux/arch/m68k/mac
cvs diff: Diffing /usr/src/linux/arch/m68k/mm
cvs diff: Diffing /usr/src/linux/arch/m68k/mvme147
cvs diff: Diffing /usr/src/linux/arch/m68k/mvme16x
cvs diff: Diffing /usr/src/linux/arch/m68k/q40
cvs diff: Diffing /usr/src/linux/arch/m68k/sun3x
cvs diff: Diffing /usr/src/linux/arch/m68k/tools
cvs diff: Diffing /usr/src/linux/arch/m68k/tools/amiga
cvs diff: Diffing /usr/src/linux/arch/mips
cvs diff: Diffing /usr/src/linux/arch/mips/boot
cvs diff: Diffing /usr/src/linux/arch/mips/jazz
cvs diff: Diffing /usr/src/linux/arch/mips/kernel
cvs diff: Diffing /usr/src/linux/arch/mips/lib
cvs diff: Diffing /usr/src/linux/arch/mips/mm
cvs diff: Diffing /usr/src/linux/arch/mips/sgi
cvs diff: Diffing /usr/src/linux/arch/mips/sgi/kernel
cvs diff: Diffing /usr/src/linux/arch/mips/sgi/prom
cvs diff: Diffing /usr/src/linux/arch/mips/sni
cvs diff: Diffing /usr/src/linux/arch/mips/tools
cvs diff: Diffing /usr/src/linux/arch/ppc
cvs diff: Diffing /usr/src/linux/arch/ppc/8xx_io
cvs diff: Diffing /usr/src/linux/arch/ppc/amiga
cvs diff: Diffing /usr/src/linux/arch/ppc/boot
cvs diff: Diffing /usr/src/linux/arch/ppc/chrpboot
cvs diff: Diffing /usr/src/linux/arch/ppc/coffboot
cvs diff: Diffing /usr/src/linux/arch/ppc/kernel
cvs diff: Diffing /usr/src/linux/arch/ppc/lib
cvs diff: Diffing /usr/src/linux/arch/ppc/mbxboot
cvs diff: Diffing /usr/src/linux/arch/ppc/mm
cvs diff: Diffing /usr/src/linux/arch/sparc
cvs diff: Diffing /usr/src/linux/arch/sparc/ap1000
cvs diff: Diffing /usr/src/linux/arch/sparc/boot
cvs diff: Diffing /usr/src/linux/arch/sparc/kernel
cvs diff: Diffing /usr/src/linux/arch/sparc/lib
cvs diff: Diffing /usr/src/linux/arch/sparc/math-emu
cvs diff: Diffing /usr/src/linux/arch/sparc/mm
cvs diff: Diffing /usr/src/linux/arch/sparc/prom
cvs diff: Diffing /usr/src/linux/arch/sparc64
cvs diff: Diffing /usr/src/linux/arch/sparc64/boot
cvs diff: Diffing /usr/src/linux/arch/sparc64/kernel
cvs diff: Diffing /usr/src/linux/arch/sparc64/lib
cvs diff: Diffing /usr/src/linux/arch/sparc64/math-emu
cvs diff: Diffing /usr/src/linux/arch/sparc64/mm
cvs diff: Diffing /usr/src/linux/arch/sparc64/prom
cvs diff: Diffing /usr/src/linux/arch/sparc64/solaris
cvs diff: Diffing /usr/src/linux/drivers
cvs diff: Diffing /usr/src/linux/drivers/acorn
cvs diff: Diffing /usr/src/linux/drivers/acorn/block
cvs diff: Diffing /usr/src/linux/drivers/acorn/char
cvs diff: Diffing /usr/src/linux/drivers/acorn/net
cvs diff: Diffing /usr/src/linux/drivers/acorn/scsi
cvs diff: Diffing /usr/src/linux/drivers/ap1000
cvs diff: Diffing /usr/src/linux/drivers/block
cvs diff: Diffing /usr/src/linux/drivers/block/paride
cvs diff: Diffing /usr/src/linux/drivers/cdrom
cvs diff: Diffing /usr/src/linux/drivers/char
cvs diff: Diffing /usr/src/linux/drivers/char/ftape
cvs diff: Diffing /usr/src/linux/drivers/char/ftape/compressor
cvs diff: Diffing /usr/src/linux/drivers/char/ftape/lowlevel
cvs diff: Diffing /usr/src/linux/drivers/char/ftape/zftape
cvs diff: Diffing /usr/src/linux/drivers/char/hfmodem
cvs diff: Diffing /usr/src/linux/drivers/char/joystick
cvs diff: Diffing /usr/src/linux/drivers/dio
cvs diff: Diffing /usr/src/linux/drivers/fc4
cvs diff: Diffing /usr/src/linux/drivers/isdn
cvs diff: Diffing /usr/src/linux/drivers/isdn/act2000
cvs diff: Diffing /usr/src/linux/drivers/isdn/avmb1
cvs diff: Diffing /usr/src/linux/drivers/isdn/hisax
cvs diff: Diffing /usr/src/linux/drivers/isdn/icn
cvs diff: Diffing /usr/src/linux/drivers/isdn/isdnloop
cvs diff: Diffing /usr/src/linux/drivers/isdn/pcbit
cvs diff: Diffing /usr/src/linux/drivers/isdn/sc
cvs diff: Diffing /usr/src/linux/drivers/macintosh
cvs diff: Diffing /usr/src/linux/drivers/misc
cvs diff: Diffing /usr/src/linux/drivers/net
cvs diff: Diffing /usr/src/linux/drivers/net/hamradio
cvs diff: Diffing /usr/src/linux/drivers/net/hamradio/soundmodem
cvs diff: Diffing /usr/src/linux/drivers/net/irda
cvs diff: Diffing /usr/src/linux/drivers/nubus
cvs diff: Diffing /usr/src/linux/drivers/pci
cvs diff: Diffing /usr/src/linux/drivers/pnp
cvs diff: Diffing /usr/src/linux/drivers/sbus
cvs diff: Diffing /usr/src/linux/drivers/sbus/audio
cvs diff: Diffing /usr/src/linux/drivers/sbus/char
cvs diff: Diffing /usr/src/linux/drivers/scsi
cvs diff: Diffing /usr/src/linux/drivers/scsi/aic7xxx
cvs diff: Diffing /usr/src/linux/drivers/sgi
cvs diff: Diffing /usr/src/linux/drivers/sgi/char
cvs diff: Diffing /usr/src/linux/drivers/sound
cvs diff: Diffing /usr/src/linux/drivers/sound/lowlevel
cvs diff: Diffing /usr/src/linux/drivers/usb
cvs diff: Diffing /usr/src/linux/drivers/usb/maps
cvs diff: Diffing /usr/src/linux/drivers/video
cvs diff: Diffing /usr/src/linux/drivers/zorro
cvs diff: Diffing /usr/src/linux/fs
cvs diff: Diffing /usr/src/linux/fs/adfs
cvs diff: Diffing /usr/src/linux/fs/affs
cvs diff: Diffing /usr/src/linux/fs/autofs
cvs diff: Diffing /usr/src/linux/fs/coda
cvs diff: Diffing /usr/src/linux/fs/devpts
cvs diff: Diffing /usr/src/linux/fs/ext2
cvs diff: Diffing /usr/src/linux/fs/fat
cvs diff: Diffing /usr/src/linux/fs/hfs
cvs diff: Diffing /usr/src/linux/fs/hpfs
cvs diff: Diffing /usr/src/linux/fs/isofs
cvs diff: Diffing /usr/src/linux/fs/lockd
cvs diff: Diffing /usr/src/linux/fs/minix
cvs diff: Diffing /usr/src/linux/fs/msdos
cvs diff: Diffing /usr/src/linux/fs/ncpfs
cvs diff: Diffing /usr/src/linux/fs/nfs
cvs diff: Diffing /usr/src/linux/fs/nfsd
cvs diff: Diffing /usr/src/linux/fs/nls
cvs diff: Diffing /usr/src/linux/fs/ntfs
cvs diff: Diffing /usr/src/linux/fs/proc
cvs diff: Diffing /usr/src/linux/fs/qnx4
cvs diff: Diffing /usr/src/linux/fs/romfs
cvs diff: Diffing /usr/src/linux/fs/smbfs
cvs diff: Diffing /usr/src/linux/fs/sysv
cvs diff: Diffing /usr/src/linux/fs/ufs
cvs diff: Diffing /usr/src/linux/fs/umsdos
cvs diff: Diffing /usr/src/linux/fs/vfat
cvs diff: Diffing /usr/src/linux/include
cvs diff: Diffing /usr/src/linux/include/asm-alpha
cvs diff: Diffing /usr/src/linux/include/asm-arm
cvs diff: Diffing /usr/src/linux/include/asm-arm/arch-arc
cvs diff: Diffing /usr/src/linux/include/asm-arm/arch-ebsa110
cvs diff: Diffing /usr/src/linux/include/asm-arm/arch-ebsa285
cvs diff: Diffing /usr/src/linux/include/asm-arm/arch-nexuspci
cvs diff: Diffing /usr/src/linux/include/asm-arm/arch-rpc
cvs diff: Diffing /usr/src/linux/include/asm-arm/arch-vnc
cvs diff: Diffing /usr/src/linux/include/asm-arm/proc-armo
cvs diff: Diffing /usr/src/linux/include/asm-arm/proc-armv
cvs diff: Diffing /usr/src/linux/include/asm-generic
cvs diff: Diffing /usr/src/linux/include/asm-i386
cvs diff: Diffing /usr/src/linux/include/asm-m68k
cvs diff: Diffing /usr/src/linux/include/asm-mips
cvs diff: Diffing /usr/src/linux/include/asm-ppc
cvs diff: Diffing /usr/src/linux/include/asm-sparc
cvs diff: Diffing /usr/src/linux/include/asm-sparc/ap1000
cvs diff: Diffing /usr/src/linux/include/asm-sparc64
cvs diff: Diffing /usr/src/linux/include/linux
cvs diff: Diffing /usr/src/linux/include/linux/byteorder
cvs diff: Diffing /usr/src/linux/include/linux/lockd
cvs diff: Diffing /usr/src/linux/include/linux/nfsd
cvs diff: Diffing /usr/src/linux/include/linux/sunrpc
cvs diff: Diffing /usr/src/linux/include/net
cvs diff: Diffing /usr/src/linux/include/net/irda
cvs diff: Diffing /usr/src/linux/include/scsi
cvs diff: Diffing /usr/src/linux/include/video
cvs diff: Diffing /usr/src/linux/init
cvs diff: Diffing /usr/src/linux/ipc
cvs diff: Diffing /usr/src/linux/kernel
cvs diff: Diffing /usr/src/linux/kernel/debug
cvs diff: Diffing /usr/src/linux/lib
cvs diff: Diffing /usr/src/linux/mm
cvs diff: Diffing /usr/src/linux/net
cvs diff: Diffing /usr/src/linux/net/802
cvs diff: Diffing /usr/src/linux/net/802/pseudo
cvs diff: Diffing /usr/src/linux/net/802/transit
cvs diff: Diffing /usr/src/linux/net/appletalk
cvs diff: Diffing /usr/src/linux/net/ax25
cvs diff: Diffing /usr/src/linux/net/bridge
cvs diff: Diffing /usr/src/linux/net/core
cvs diff: Diffing /usr/src/linux/net/decnet
cvs diff: Diffing /usr/src/linux/net/econet
cvs diff: Diffing /usr/src/linux/net/ethernet
cvs diff: Diffing /usr/src/linux/net/ipv4
cvs diff: Diffing /usr/src/linux/net/ipv6
cvs diff: Diffing /usr/src/linux/net/ipx
cvs diff: Diffing /usr/src/linux/net/irda
cvs diff: Diffing /usr/src/linux/net/irda/compressors
cvs diff: Diffing /usr/src/linux/net/irda/ircomm
cvs diff: Diffing /usr/src/linux/net/irda/irlan
cvs diff: Diffing /usr/src/linux/net/irda/irlpt
cvs diff: Diffing /usr/src/linux/net/irda/irobex
cvs diff: Diffing /usr/src/linux/net/lapb
cvs diff: Diffing /usr/src/linux/net/netlink
cvs diff: Diffing /usr/src/linux/net/netrom
cvs diff: Diffing /usr/src/linux/net/packet
cvs diff: Diffing /usr/src/linux/net/rose
cvs diff: Diffing /usr/src/linux/net/sched
cvs diff: Diffing /usr/src/linux/net/sunrpc
cvs diff: Diffing /usr/src/linux/net/unix
cvs diff: Diffing /usr/src/linux/net/wanrouter
cvs diff: Diffing /usr/src/linux/net/x25
cvs diff: Diffing /usr/src/linux/scripts
cvs diff: Diffing /usr/src/linux/scripts/ksymoops
cvs diff: Diffing /usr/src/linux/scripts/lxdialog
cvs diff: Diffing /usr/src/linux/scripts/memleak
1.66user 0.64system 0:02.29elapsed 100%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (150major+6093minor)pagefaults 0swaps
andrea@laser:~$ ]0;andrea@laser:~[Kexit
Script done on Fri May 14 12:40:53 1999
2sec to cvs diff a whole 2.3.1 kernel tree with all kernels since 2.0.0
(and most pre-patches) in the repository.
I know this is not possible in the stock kenrel but it's due the current
design of flushtime, not because you run uptime every 5 sec. I can run
uptime every msec and I get the same numbers.
What you should care are _only_ the numbers in /proc/sys/vm/bdflush
relative to the buffer and super-buffer ages but only once you'll get
flushtime fixed.
>The per-wakeup write limit was too small, and there was no hard limit of
>dirty buffer age. The result was that in situations where there's a lot of
>write I/O happening, the disk would be underutilized, but then the buffer
>would eventually hit its max dirty buffer percentage and it would start
>writing like crazy. It was really bad with update running, doing its sync
>every 30s. System capacity would drop to 50% for 5s every 30s. Very bad.
>In short, the writes weren't being paced.
I agree and I just fixed the flushtime handling last month. If you want to
get it fixed start using my current tree (that btw rejects completly the
2.2.8 buffer changes).
I think I'll post a patch against 2.2.8 (hopefully today) that will port
by current buffer code to 2.2.8.
Now I ask you to try out (and benchmark) one of my last two andrea
patches. Then I'll ask you to try my new buffer code alone over 2.2.8.
Thanks.
Andrea Arcangeli
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