Re: [HACKERS] fsync vs open_sync

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pgsql(at)mohawksoft(dot)com wrote:
|>>Anyway, with fsync enabled using standard fsync(), I get roughly
|>
|>300-400
|>
|>>inserts per second. With fsync disabled, I get about 7000 inserts per
|>>second. When I re-enable fsync but use the open_sync option, I can get
|>>about 2500 inserts per second.
|>
|>You are getting 300-400 inserts/sec with fsync on? If you don't mind me
|>asking, what's your hardware? (also, have you checked fsync on #s with
|>the new bgwriter in 7.5?)
|>
|
|
| 300 inserts persecond with fsync on using fdatasync. 2500 inserts per
| second with fsync on using open_sync.
|
| [mwoodward(at)penguin-021 mwoodward]$ cat /proc/cpuinfo
| processor : 0
| vendor_id : GenuineIntel
| cpu family : 15
| model : 2
| model name : Intel(R) Xeon(TM) CPU 2.40GHz
| stepping : 5
| cpu MHz : 2399.373
| cache size : 512 KB
| fdiv_bug : no
| hlt_bug : no
| f00f_bug : no
| coma_bug : no
| fpu : yes
| fpu_exception : yes
| cpuid level : 2
| wp : yes
| flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
| cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe cid
| bogomips : 4784.12
|
| Linux node1 2.4.25 #1 Mon Mar 22 13:33:41 EST 2004 i686 i686 i386 GNU/Linux
|
| ide2: BM-DMA at 0xc400-0xc407, BIOS settings: hde:pio, hdf:pio
| hde: Maxtor 6Y200P0, ATA DISK drive
| hde: attached ide-disk driver.
| hde: host protected area => 1
| hde: 398297088 sectors (203928 MB) w/7936KiB Cache, CHS=24792/255/63,
| UDMA(100)
|
| PDC20268: IDE controller at PCI slot 06:05.0

I did some experiments too:

inserting 10000 rows in a table with an integer column:

fsync=false ====> ~7.5 secs 1300 insert/sec

wal_sync_method=fsync ====> ~15.5 secs 645 insert/sec
wal_sync_method=fdatasync ====> ~15.5 secs 645 insert/sec
wal_sync_method=open_sync ====> ~10.0 secs 1000 insert/sec
wal_sync_method=open_datasync ====> <the server doesn't start>

Test bed: Postgresql 8.0beta1, linux kernel 2.4.22,
~ hda: IC35L060AVVA07-0, ATA DISK drive
~ hda: 120103200 sectors (61493 MB) w/1863KiB Cache, CHS=7476/255/63, UDMA(100)

# cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 8
model name : Pentium III (Coppermine)
stepping : 6
cpu MHz : 877.500
cache size : 256 KB
physical id : 0
siblings : 1
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse
runqueue : 0

bogomips : 1749.81

processor : 1
vendor_id : GenuineIntel
cpu family : 6
model : 8
model name : Pentium III (Coppermine)
stepping : 6
cpu MHz : 877.500
cache size : 256 KB
physical id : 0
siblings : 1
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse
runqueue : 1

bogomips : 1749.81

Regards
Gaetano Mendola

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