low(er) disk performance with sched_4bsd then with sched_ule
Oliver Lehmann
lehmann at ans-netz.de
Wed Sep 14 10:45:59 PDT 2005
Hi,
I've a dual-cpu system (SMP) which runs with 2 PIII-850 MHz on an Intel
Serverboard (440GX chipset). My diskspace is provided by a RAID-5
containing 4 WD2500KS harddrives connected to a 3ware 9500S-4LP
controller which runs at 32bit/33MHz.
The system itself runs FreeBSD 6.0-BETA2.
with SCHED_4BSD in the kernel:
root at nudel olivleh1> dd if=/dev/zero of=/mnt/files/test.dd bs=64k count=32000
32000+0 records in
32000+0 records out
2097152000 bytes transferred in 44.136711 secs (47514913 bytes/sec)
with SCHED_ULE in the kernel:
root at nudel olivleh1> dd if=/dev/zero of=/mnt/files/test.dd bs=64k count=32000
32000+0 records in
32000+0 records out
2097152000 bytes transferred in 27.005334 secs (77656954 bytes/sec)
the scheduler is the only difference between both configs - everything
else is the same. Kernel debugging is disabled, malloc.conf exists.
Filesystem Size Used Avail Capacity Mounted on
/dev/da0s1a 496M 159M 297M 35% /
devfs 1.0K 1.0K 0B 100% /dev
/dev/da0s1d 496M 20M 436M 4% /var
/dev/da0s1e 496M 22M 434M 5% /tmp
/dev/da0s1f 19G 2.9G 15G 16% /usr
/dev/da0s1g 671G 216G 455G 32% /mnt/files
3ware device driver for 9000 series storage controllers, version: 3.60.00.017
twa0: <3ware 9000 series Storage Controller> port 0x3400-0x34ff mem 0xf4102800-0xf41028ff,0xf4800000-0xf4ffffff irq 16 at device 16.0 on pci0
twa0: [FAST]
twa0: INFO: (0x15: 0x1300): Controller details:: 4 ports, Firmware FE9X 2.08.00.005, BIOS BE9X 2.03.01.052
da0 at twa0 bus 0 target 0 lun 0
da0: <AMCC 9500S-4LP DISK 2.08> Fixed Direct Access SCSI-3 device
da0: 100.000MB/s transfers
da0: 715224MB (1464778752 512 byte sectors: 255H 63S/T 91178C)
Any idea where the 30MB/sec drawback comes from and if I missed sth.?
I mean why there are 30MB/s more or less is worth to think about imho.
--
Oliver Lehmann
http://www.pofo.de/
http://wishlist.ans-netz.de/
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