very slow writes with softdep enabled on mpi(4)

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very slow writes with softdep enabled on mpi(4)

Mattieu Baptiste
Hi all,

It's really weird. I see very slow writes when softdep is enabled.
Write caches seem to be enabled on disks. Utilities like bonnie++
confirm that writes are very slow with softdep enabled (although it
helps with lots of file creations). This happens whether I use native
disks or RAID 1 volume behind mpi(4) (on which the controller's cache
is also enabled).

With softdep:
# mount -o softdep /dev/sd2a /mnt
# dd if=/dev/zero of=/mnt/test
# dd if=/dev/zero of=/mnt/test.dump bs=4k count=10000
10000+0 records in
10000+0 records out
40960000 bytes transferred in 16.060 secs (2550321 bytes/sec)
# rm /mnt/test.dump
# dd if=/dev/zero of=/mnt/test.dump bs=1m count=100
100+0 records in
100+0 records out
104857600 bytes transferred in 3.483 secs (30101713 bytes/sec)

Without softdep:
# mount /dev/sd2a /mnt
# dd if=/dev/zero of=/mnt/test.dump bs=4k count=10000
10000+0 records in
10000+0 records out
40960000 bytes transferred in 0.330 secs (123880958 bytes/sec)
# rm /mnt/test.dump
# dd if=/dev/zero of=/mnt/test.dump bs=1m count=100
100+0 records in
100+0 records out
104857600 bytes transferred in 0.932 secs (112438785 bytes/sec)

# scsi -f /dev/rsd2c -m8
IC:  1
ABPF:  0
CAP:  0
DISC:  1
SIZE:  0
WCE:  1
MF:  0
RCD:  0
Demand Retention Priority:  0
Write Retention Priority:  0
Disable Pre-fetch Transfer Length:  65535
Minimum Pre-fetch:  0
Maximum Pre-fetch:  65535
Maximum Pre-fetch Ceiling:  65535
FSW:  0
LBCSS:  0
DRA:  0
Vendor-specific:  0
NV_DIS:  0
Number of Cache Segments:  2
Cache Segment Size:  0


dmesg:
console is /pci@1e,600000/isa@7/serial@0,3f8
Copyright (c) 1982, 1986, 1989, 1991, 1993
        The Regents of the University of California.  All rights reserved.
Copyright (c) 1995-2011 OpenBSD. All rights reserved.  http://www.OpenBSD.org

OpenBSD 5.0-beta (GENERIC.MP) #3: Tue Jul 19 18:20:17 CEST 2011
    [hidden email]:/usr/src/sys/arch/sparc64/compile/GENERIC.MP
real mem = 17179869184 (16384MB)
avail mem = 16901693440 (16118MB)
mainbus0 at root: Sun Fire V440
cpu0 at mainbus0: SUNW,UltraSPARC-IIIi (rev 2.4) @ 1281 MHz
cpu0: physical 32K instruction (32 b/l), 64K data (32 b/l), 1024K
external (64 b/l)
cpu1 at mainbus0: SUNW,UltraSPARC-IIIi (rev 2.4) @ 1281 MHz
cpu1: physical 32K instruction (32 b/l), 64K data (32 b/l), 1024K
external (64 b/l)
cpu2 at mainbus0: SUNW,UltraSPARC-IIIi (rev 2.4) @ 1281 MHz
cpu2: physical 32K instruction (32 b/l), 64K data (32 b/l), 1024K
external (64 b/l)
cpu3 at mainbus0: SUNW,UltraSPARC-IIIi (rev 2.4) @ 1281 MHz
cpu3: physical 32K instruction (32 b/l), 64K data (32 b/l), 1024K
external (64 b/l)
"memory-controller" at mainbus0 not configured
"memory-controller" at mainbus0 not configured
"memory-controller" at mainbus0 not configured
"memory-controller" at mainbus0 not configured
schizo0 at mainbus0: "Tomatillo", version 4, ign 700, bus A 0 to 0
schizo0: dvma map c0000000-dfffffff
pci0 at schizo0
cas0 at pci0 dev 2 function 0 "Sun Cassini" rev 0x20: ivec 0x718,
address 00:03:ba:a4:90:53
brgphy0 at cas0 phy 1: BCM5421 10/100/1000baseT PHY, rev. 1
"ppm" at mainbus0 not configured
schizo1 at mainbus0: "Tomatillo", version 4, ign 740, bus B 0 to 1
schizo1: dvma map c0000000-dfffffff
pci1 at schizo1
ppb0 at pci1 dev 2 function 0 "Intel 21154AE/BE PCI-PCI" rev 0x00
pci2 at ppb0 bus 1
cas1 at pci2 dev 0 function 0 "Sun Cassini" rev 0x20: ivec 0x740,
address 00:03:ba:93:1c:a1
brgphy1 at cas1 phy 1: BCM5401 10/100/1000baseT PHY, rev. 3
schizo2 at mainbus0: "Tomatillo", version 4, ign 780, bus A 0 to 0
schizo2: dvma map c0000000-dfffffff
pci3 at schizo2
ebus0 at pci3 dev 7 function 0 "Acer Labs M1533 ISA" rev 0x00
"flashprom" at ebus0 addr 0-fffff, 290-290 not configured
rtc0 at ebus0 addr 70-71: m5819p
pcfiic0 at ebus0 addr 320-321 ivec 0x1b
iic0 at pcfiic0
"SUNW,i2c-imax" at iic0 addr 0xb not configured
"SUNW,i2c-imax" at iic0 addr 0xc not configured
admtemp0 at iic0 addr 0x18: max1617
"pca9555" at iic0 addr 0x21 not configured
"pca9555" at iic0 addr 0x22 not configured
"pca9555" at iic0 addr 0x23 not configured
"pca9555" at iic0 addr 0x24 not configured
"adm1026" at iic0 addr 0x2e not configured
admtemp1 at iic0 addr 0x32: max1617
admtemp2 at iic0 addr 0x40: max1617
admtemp3 at iic0 addr 0x48: max1617
lmtemp0 at iic0 addr 0x4e: lm75
spdmem0 at iic0 addr 0x5b: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem1 at iic0 addr 0x5c: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem2 at iic0 addr 0x5d: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem3 at iic0 addr 0x5e: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem4 at iic0 addr 0x63: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem5 at iic0 addr 0x64: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem6 at iic0 addr 0x65: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem7 at iic0 addr 0x66: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem8 at iic0 addr 0x6b: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem9 at iic0 addr 0x6c: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem10 at iic0 addr 0x6d: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem11 at iic0 addr 0x6e: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem12 at iic0 addr 0x73: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem13 at iic0 addr 0x74: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem14 at iic0 addr 0x75: 1GB DDR SDRAM registered ECC PC2300CL2.5
spdmem15 at iic0 addr 0x76: 1GB DDR SDRAM registered ECC PC2300CL2.5
"ics951601" at iic0 addr 0x69 not configured
power0 at ebus0 addr 800-82f ivec 0x1a
com0 at ebus0 addr 3f8-3ff ivec 0x22: ns16550a, 16 byte fifo
com0: console
com1 at ebus0 addr 2e8-2ef ivec 0x22: ns16550a, 16 byte fifo
"rmc-comm" at ebus0 addr 3e8-3ef ivec 0x22 not configured
alipm0 at pci3 dev 6 function 0 "Acer Labs M7101 Power" rev 0x00: 223KHz clock
iic1 at alipm0
ohci0 at pci3 dev 10 function 0 "Acer Labs M5237 USB" rev 0x03: ivec
0x7a1, version 1.0, legacy support
ohci1 at pci3 dev 11 function 0 "Acer Labs M5237 USB" rev 0x03: ivec
0x7a5, version 1.0, legacy support
pciide0 at pci3 dev 13 function 0 "Acer Labs M5229 UDMA IDE" rev 0xc4:
DMA, channel 0 configured to native-PCI, channel 1 configured to
native-PCI
pciide0: using ivec 0x7a6 for native-PCI interrupt
atapiscsi0 at pciide0 channel 0 drive 0
scsibus0 at atapiscsi0: 2 targets
cd0 at scsibus0 targ 0 lun 0: <TOSHIBA, DVD-ROM SD-C2612, 1011> ATAPI
5/cdrom removable
cd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 2
pciide0: channel 1 disabled (no drives)
usb0 at ohci0: USB revision 1.0
uhub0 at usb0 "Acer Labs OHCI root hub" rev 1.00/1.00 addr 1
usb1 at ohci1: USB revision 1.0
uhub1 at usb1 "Acer Labs OHCI root hub" rev 1.00/1.00 addr 1
"ppm" at mainbus0 not configured
schizo3 at mainbus0: "Tomatillo", version 4, ign 7c0, bus B 0 to 0
schizo3: dvma map c0000000-dfffffff
pci4 at schizo3
cas2 at pci4 dev 1 function 0 "Sun Cassini" rev 0x20: ivec 0x7dc,
address 00:03:ba:a4:90:54
brgphy2 at cas2 phy 1: BCM5421 10/100/1000baseT PHY, rev. 1
mpi0 at pci4 dev 2 function 0 "Symbios Logic 53c1030" rev 0x07: ivec 0x7e3
scsibus1 at mpi0: 16 targets, initiator 7
sd0 at scsibus1 targ 0 lun 0: <LSILOGIC, 1030 IM IM, 1000> SCSI2 0/direct fixed
sd0: 70007MB, 512 bytes/sector, 143374336 sectors
sd1 at scsibus1 targ 2 lun 0: <SEAGATE, ST314670LSUN146G, 065A> SCSI3
0/direct fixed t10.SEAGATE_ST314670LSUN146G3KS73HA9
sd1: 140009MB, 512 bytes/sector, 286739329 sectors
sd2 at scsibus1 targ 3 lun 0: <SEAGATE, ST314670LSUN146G, 065A> SCSI3
0/direct fixed t10.SEAGATE_ST314670LSUN146G3KS73JGX
sd2: 140009MB, 512 bytes/sector, 286739329 sectors
mpi0: target 2 Sync at 160MHz width 16bit offset 63 QAS 1 DT 1 IU 1
mpi0: target 3 Sync at 160MHz width 16bit offset 63 QAS 1 DT 1 IU 1
mpi0: phys disk 0 Sync at 160MHz width 16bit offset 63 QAS 1 DT 1 IU 1
mpi0: phys disk 1 Sync at 160MHz width 16bit offset 63 QAS 1 DT 1 IU 1
mpi1 at pci4 dev 2 function 1 "Symbios Logic 53c1030" rev 0x07: ivec 0x7e4
scsibus2 at mpi1: 16 targets, initiator 7
"i2c" at mainbus0 not configured
vscsi0 at root
scsibus3 at vscsi0: 256 targets
softraid0 at root
scsibus4 at softraid0: 256 targets
bootpath: /pci@1f,700000/scsi@2,0/disk@0,0
root on sd0a swap on sd0b dump on sd0b


--
Mattieu Baptiste
"/earth is 102% full ... please delete anyone you can."

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Re: very slow writes with softdep enabled on mpi(4)

Mattieu Baptiste
On Mon, Jul 25, 2011 at 5:54 PM, Mattieu Baptiste <[hidden email]>
wrote:
> Hi all,
>
> It's really weird. I see very slow writes when softdep is enabled.
> Write caches seem to be enabled on disks. Utilities like bonnie++
> confirm that writes are very slow with softdep enabled (although it
> helps with lots of file creations). This happens whether I use native
> disks or RAID 1 volume behind mpi(4) (on which the controller's cache
> is also enabled).

After digging around this problem with help from Pedro, I noticed that
a 4.9-release kernel works ok, whereas a 5.0-beta does not. So I tried
to identify which commit was responsible and found out this one is
responsible of *very* slow writes with softdep (I only have this bug
on sparc64):
http://marc.info/?l=openbsd-cvs&m=130730313107059&w=2

I can add that this bug is just affecting softdep:
- dd'ing to the raw device is fast,
- dd'ing to the file system mounted sync is very fast,
- dd'ing to the file system mounted async is very fast,
- dd'ing to the file system mounted with softdep is very slow.

I can also add that changing a working kernel to bufcachepercent >=42
via sysctl is ok too.


>
> With softdep:
> # mount -o softdep /dev/sd2a /mnt
> # dd if=/dev/zero of=/mnt/test
> # dd if=/dev/zero of=/mnt/test.dump bs=4k count=10000
> 10000+0 records in
> 10000+0 records out
> 40960000 bytes transferred in 16.060 secs (2550321 bytes/sec)
> # rm /mnt/test.dump
> # dd if=/dev/zero of=/mnt/test.dump bs=1m count=100
> 100+0 records in
> 100+0 records out
> 104857600 bytes transferred in 3.483 secs (30101713 bytes/sec)
>
> Without softdep:
> # mount /dev/sd2a /mnt
> # dd if=/dev/zero of=/mnt/test.dump bs=4k count=10000
> 10000+0 records in
> 10000+0 records out
> 40960000 bytes transferred in 0.330 secs (123880958 bytes/sec)
> # rm /mnt/test.dump
> # dd if=/dev/zero of=/mnt/test.dump bs=1m count=100
> 100+0 records in
> 100+0 records out
> 104857600 bytes transferred in 0.932 secs (112438785 bytes/sec)
>
> # scsi -f /dev/rsd2c -m8
> IC:  1
> ABPF:  0
> CAP:  0
> DISC:  1
> SIZE:  0
> WCE:  1
> MF:  0
> RCD:  0
> Demand Retention Priority:  0
> Write Retention Priority:  0
> Disable Pre-fetch Transfer Length:  65535
> Minimum Pre-fetch:  0
> Maximum Pre-fetch:  65535
> Maximum Pre-fetch Ceiling:  65535
> FSW:  0
> LBCSS:  0
> DRA:  0
> Vendor-specific:  0
> NV_DIS:  0
> Number of Cache Segments:  2
> Cache Segment Size:  0
>
>
> dmesg:
> console is /pci@1e,600000/isa@7/serial@0,3f8
> Copyright (c) 1982, 1986, 1989, 1991, 1993
>        The Regents of the University of California.  All rights reserved.
> Copyright (c) 1995-2011 OpenBSD. All rights reserved.
 http://www.OpenBSD.org

>
> OpenBSD 5.0-beta (GENERIC.MP) #3: Tue Jul 19 18:20:17 CEST 2011
>    [hidden email]:/usr/src/sys/arch/sparc64/compile/GENERIC.MP
> real mem = 17179869184 (16384MB)
> avail mem = 16901693440 (16118MB)
> mainbus0 at root: Sun Fire V440
> cpu0 at mainbus0: SUNW,UltraSPARC-IIIi (rev 2.4) @ 1281 MHz
> cpu0: physical 32K instruction (32 b/l), 64K data (32 b/l), 1024K
> external (64 b/l)
> cpu1 at mainbus0: SUNW,UltraSPARC-IIIi (rev 2.4) @ 1281 MHz
> cpu1: physical 32K instruction (32 b/l), 64K data (32 b/l), 1024K
> external (64 b/l)
> cpu2 at mainbus0: SUNW,UltraSPARC-IIIi (rev 2.4) @ 1281 MHz
> cpu2: physical 32K instruction (32 b/l), 64K data (32 b/l), 1024K
> external (64 b/l)
> cpu3 at mainbus0: SUNW,UltraSPARC-IIIi (rev 2.4) @ 1281 MHz
> cpu3: physical 32K instruction (32 b/l), 64K data (32 b/l), 1024K
> external (64 b/l)
> "memory-controller" at mainbus0 not configured
> "memory-controller" at mainbus0 not configured
> "memory-controller" at mainbus0 not configured
> "memory-controller" at mainbus0 not configured
> schizo0 at mainbus0: "Tomatillo", version 4, ign 700, bus A 0 to 0
> schizo0: dvma map c0000000-dfffffff
> pci0 at schizo0
> cas0 at pci0 dev 2 function 0 "Sun Cassini" rev 0x20: ivec 0x718,
> address 00:03:ba:a4:90:53
> brgphy0 at cas0 phy 1: BCM5421 10/100/1000baseT PHY, rev. 1
> "ppm" at mainbus0 not configured
> schizo1 at mainbus0: "Tomatillo", version 4, ign 740, bus B 0 to 1
> schizo1: dvma map c0000000-dfffffff
> pci1 at schizo1
> ppb0 at pci1 dev 2 function 0 "Intel 21154AE/BE PCI-PCI" rev 0x00
> pci2 at ppb0 bus 1
> cas1 at pci2 dev 0 function 0 "Sun Cassini" rev 0x20: ivec 0x740,
> address 00:03:ba:93:1c:a1
> brgphy1 at cas1 phy 1: BCM5401 10/100/1000baseT PHY, rev. 3
> schizo2 at mainbus0: "Tomatillo", version 4, ign 780, bus A 0 to 0
> schizo2: dvma map c0000000-dfffffff
> pci3 at schizo2
> ebus0 at pci3 dev 7 function 0 "Acer Labs M1533 ISA" rev 0x00
> "flashprom" at ebus0 addr 0-fffff, 290-290 not configured
> rtc0 at ebus0 addr 70-71: m5819p
> pcfiic0 at ebus0 addr 320-321 ivec 0x1b
> iic0 at pcfiic0
> "SUNW,i2c-imax" at iic0 addr 0xb not configured
> "SUNW,i2c-imax" at iic0 addr 0xc not configured
> admtemp0 at iic0 addr 0x18: max1617
> "pca9555" at iic0 addr 0x21 not configured
> "pca9555" at iic0 addr 0x22 not configured
> "pca9555" at iic0 addr 0x23 not configured
> "pca9555" at iic0 addr 0x24 not configured
> "adm1026" at iic0 addr 0x2e not configured
> admtemp1 at iic0 addr 0x32: max1617
> admtemp2 at iic0 addr 0x40: max1617
> admtemp3 at iic0 addr 0x48: max1617
> lmtemp0 at iic0 addr 0x4e: lm75
> spdmem0 at iic0 addr 0x5b: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem1 at iic0 addr 0x5c: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem2 at iic0 addr 0x5d: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem3 at iic0 addr 0x5e: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem4 at iic0 addr 0x63: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem5 at iic0 addr 0x64: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem6 at iic0 addr 0x65: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem7 at iic0 addr 0x66: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem8 at iic0 addr 0x6b: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem9 at iic0 addr 0x6c: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem10 at iic0 addr 0x6d: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem11 at iic0 addr 0x6e: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem12 at iic0 addr 0x73: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem13 at iic0 addr 0x74: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem14 at iic0 addr 0x75: 1GB DDR SDRAM registered ECC PC2300CL2.5
> spdmem15 at iic0 addr 0x76: 1GB DDR SDRAM registered ECC PC2300CL2.5
> "ics951601" at iic0 addr 0x69 not configured
> power0 at ebus0 addr 800-82f ivec 0x1a
> com0 at ebus0 addr 3f8-3ff ivec 0x22: ns16550a, 16 byte fifo
> com0: console
> com1 at ebus0 addr 2e8-2ef ivec 0x22: ns16550a, 16 byte fifo
> "rmc-comm" at ebus0 addr 3e8-3ef ivec 0x22 not configured
> alipm0 at pci3 dev 6 function 0 "Acer Labs M7101 Power" rev 0x00: 223KHz
clock

> iic1 at alipm0
> ohci0 at pci3 dev 10 function 0 "Acer Labs M5237 USB" rev 0x03: ivec
> 0x7a1, version 1.0, legacy support
> ohci1 at pci3 dev 11 function 0 "Acer Labs M5237 USB" rev 0x03: ivec
> 0x7a5, version 1.0, legacy support
> pciide0 at pci3 dev 13 function 0 "Acer Labs M5229 UDMA IDE" rev 0xc4:
> DMA, channel 0 configured to native-PCI, channel 1 configured to
> native-PCI
> pciide0: using ivec 0x7a6 for native-PCI interrupt
> atapiscsi0 at pciide0 channel 0 drive 0
> scsibus0 at atapiscsi0: 2 targets
> cd0 at scsibus0 targ 0 lun 0: <TOSHIBA, DVD-ROM SD-C2612, 1011> ATAPI
> 5/cdrom removable
> cd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 2
> pciide0: channel 1 disabled (no drives)
> usb0 at ohci0: USB revision 1.0
> uhub0 at usb0 "Acer Labs OHCI root hub" rev 1.00/1.00 addr 1
> usb1 at ohci1: USB revision 1.0
> uhub1 at usb1 "Acer Labs OHCI root hub" rev 1.00/1.00 addr 1
> "ppm" at mainbus0 not configured
> schizo3 at mainbus0: "Tomatillo", version 4, ign 7c0, bus B 0 to 0
> schizo3: dvma map c0000000-dfffffff
> pci4 at schizo3
> cas2 at pci4 dev 1 function 0 "Sun Cassini" rev 0x20: ivec 0x7dc,
> address 00:03:ba:a4:90:54
> brgphy2 at cas2 phy 1: BCM5421 10/100/1000baseT PHY, rev. 1
> mpi0 at pci4 dev 2 function 0 "Symbios Logic 53c1030" rev 0x07: ivec 0x7e3
> scsibus1 at mpi0: 16 targets, initiator 7
> sd0 at scsibus1 targ 0 lun 0: <LSILOGIC, 1030 IM IM, 1000> SCSI2 0/direct
fixed

> sd0: 70007MB, 512 bytes/sector, 143374336 sectors
> sd1 at scsibus1 targ 2 lun 0: <SEAGATE, ST314670LSUN146G, 065A> SCSI3
> 0/direct fixed t10.SEAGATE_ST314670LSUN146G3KS73HA9
> sd1: 140009MB, 512 bytes/sector, 286739329 sectors
> sd2 at scsibus1 targ 3 lun 0: <SEAGATE, ST314670LSUN146G, 065A> SCSI3
> 0/direct fixed t10.SEAGATE_ST314670LSUN146G3KS73JGX
> sd2: 140009MB, 512 bytes/sector, 286739329 sectors
> mpi0: target 2 Sync at 160MHz width 16bit offset 63 QAS 1 DT 1 IU 1
> mpi0: target 3 Sync at 160MHz width 16bit offset 63 QAS 1 DT 1 IU 1
> mpi0: phys disk 0 Sync at 160MHz width 16bit offset 63 QAS 1 DT 1 IU 1
> mpi0: phys disk 1 Sync at 160MHz width 16bit offset 63 QAS 1 DT 1 IU 1
> mpi1 at pci4 dev 2 function 1 "Symbios Logic 53c1030" rev 0x07: ivec 0x7e4
> scsibus2 at mpi1: 16 targets, initiator 7
> "i2c" at mainbus0 not configured
> vscsi0 at root
> scsibus3 at vscsi0: 256 targets
> softraid0 at root
> scsibus4 at softraid0: 256 targets
> bootpath: /pci@1f,700000/scsi@2,0/disk@0,0
> root on sd0a swap on sd0b dump on sd0b
>
>
> --
> Mattieu Baptiste
> "/earth is 102% full ... please delete anyone you can."
>



--
Mattieu Baptiste
"/earth is 102% full ... please delete anyone you can."

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Re: very slow writes with softdep enabled on mpi(4)

Ted Unangst-2
In reply to this post by Mattieu Baptiste
On Fri, Jul 29, 2011, Mattieu Baptiste wrote:

> After digging around this problem with help from Pedro, I noticed that
> a 4.9-release kernel works ok, whereas a 5.0-beta does not. So I tried
> to identify which commit was responsible and found out this one is
> responsible of *very* slow writes with softdep (I only have this bug
> on sparc64):
> http://marc.info/?l=openbsd-cvs&m=130730313107059&w=2
>
> I can add that this bug is just affecting softdep:
> - dd'ing to the raw device is fast,
> - dd'ing to the file system mounted sync is very fast,
> - dd'ing to the file system mounted async is very fast,
> - dd'ing to the file system mounted with softdep is very slow.
>
> I can also add that changing a working kernel to bufcachepercent >=42
> via sysctl is ok too.

What happens if you change bufcachepercent to a much smaller value, like
the 4.9 default?

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Re: very slow writes with softdep enabled on mpi(4)

Mattieu Baptiste
On Fri, Jul 29, 2011 at 11:58 PM, Ted Unangst <[hidden email]> wrote:

> On Fri, Jul 29, 2011, Mattieu Baptiste wrote:
>
>> After digging around this problem with help from Pedro, I noticed that
>> a 4.9-release kernel works ok, whereas a 5.0-beta does not. So I tried
>> to identify which commit was responsible and found out this one is
>> responsible of *very* slow writes with softdep (I only have this bug
>> on sparc64):
>> http://marc.info/?l=openbsd-cvs&m=130730313107059&w=2
>>
>> I can add that this bug is just affecting softdep:
>> - dd'ing to the raw device is fast,
>> - dd'ing to the file system mounted sync is very fast,
>> - dd'ing to the file system mounted async is very fast,
>> - dd'ing to the file system mounted with softdep is very slow.
>>
>> I can also add that changing a working kernel to bufcachepercent >=42
>> via sysctl is ok too.
>
> What happens if you change bufcachepercent to a much smaller value, like
> the 4.9 default?

If I change kern.bufcachepercent via sysctl to 10 or 5, it's still very slow.


--
Mattieu Baptiste
"/earth is 102% full ... please delete anyone you can."

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Re: very slow writes with softdep enabled on mpi(4)

Mattieu Baptiste
On Sat, Jul 30, 2011 at 1:38 AM, Mattieu Baptiste <[hidden email]> wrote:

> On Fri, Jul 29, 2011 at 11:58 PM, Ted Unangst <[hidden email]> wrote:
>> On Fri, Jul 29, 2011, Mattieu Baptiste wrote:
>>
>>> After digging around this problem with help from Pedro, I noticed that
>>> a 4.9-release kernel works ok, whereas a 5.0-beta does not. So I tried
>>> to identify which commit was responsible and found out this one is
>>> responsible of *very* slow writes with softdep (I only have this bug
>>> on sparc64):
>>> http://marc.info/?l=openbsd-cvs&m=130730313107059&w=2
>>>
>>> I can add that this bug is just affecting softdep:
>>> - dd'ing to the raw device is fast,
>>> - dd'ing to the file system mounted sync is very fast,
>>> - dd'ing to the file system mounted async is very fast,
>>> - dd'ing to the file system mounted with softdep is very slow.
>>>
>>> I can also add that changing a working kernel to bufcachepercent >=42
>>> via sysctl is ok too.
>>
>> What happens if you change bufcachepercent to a much smaller value, like
>> the 4.9 default?
>
> If I change kern.bufcachepercent via sysctl to 10 or 5, it's still very slow.

But... if I set BUFCACHEPERCENT to 10 in sys/conf/param.c, softdep is
fast again.

--
Mattieu Baptiste
"/earth is 102% full ... please delete anyone you can."