Re: [HACKERS] fsync vs open_sync

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pgsql@mohawksoft.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@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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