Reply Inline ! --- Satinder <jeet_sat12@xxxxxxxxxxx> wrote: > Hi All, > I am having few queries related to > the Tagged Command Queuing(TCQ) in SCSI . > I am not clear whether this is the property of > SCSI Devices or the adapter controller that is > handing the device?Or implemented at driver level? > Tagged command queueing ======================== http://www.wdc.com/en/library/sata/2579-001076.pdf > Is this can be changed or configured, if yes then > how? SCSI Tuning ============ http://people.redhat.com/alikins/system_tuning.html#scsi > It would be nice if someone could please > explain that what does term ?outstanding IO? means > in SCSI device context. Is this same as tagged queue > depth. HOw this is handled at SCSI driver? > > How could this (TCQ) affect the disk throughput ? > IDE v/s SCSI ============= http://www.csl.cornell.edu/~bwhite/papers/ide_scsi.pdf > I have tried to modify the TCQ as explained in > aic79xx documentation. > I have added following line in file > /etc/modprobe.conf > > options aic79xx aic 79xx=tag_info:{{64,64}} <- for > target 0 and 1 > > But dmesg It is still is queue depth is 4 (This > is the same value as set in .config file > CONFIG_AIC79XX_CMDS_PER_DEVICE) > Also it is explained in document that its default > value is 32. > See http://lxr.linux.no/source/Documentation/scsi/scsi_mid_low_api.txt?v=2.6.10 --> scsi_adjust_queue_depth() Probably scsitools [ scsi-config ] may help , not sure ......... > My system is having 2 SCSI hard disks discription > is as given below.I am using linux kernel version > 2.6.9 stock kernel. > > # cat /proc/scsi/scsi > Attached devices: > Host: scsi0 Channel: 00 Id: 00 Lun: 00 > Vendor: SEAGATE Model: ST39140W Rev: > 1498 > Type: Direct-Access ANSI > SCSI revision: 02 > Host: scsi0 Channel: 00 Id: 01 Lun: 00 > Vendor: COMPAQ Model: BD009222C7 Rev: > B016 > Type: Direct-Access ANSI > SCSI revision: 02 > > SCSI controller is > #lspci | grep ?storage controller? > 00:08.0 SCSI storage controller: Adaptec > ASC-29320A U320 (rev 10) > The low level SCSI driver is aic79xx.Here is dmesg > output ( SCSI part ). > #dmesg > > SCSI subsystem > initialized > ACPI: PCI interrupt 0000:00:08.0[A] -> GSI 11 > (level, low) -> IRQ 11 > scsi0 : Adaptec AIC79XX PCI-X SCSI HBA DRIVER, Rev > 1.3.11 > <Adaptec 29320A Ultra320 SCSI adapter> > aic7901: Ultra320 Wide Channel A, SCSI > Id=15, PCI 33 or 66Mhz, 512 SCBs > (scsi0:A:0): 40.000MB/s transfers (20.000MHz, > 16bit) > (scsi0:A:1): 40.000MB/s transfers (20.000MHz, > 16bit) > Vendor: SEAGATE Model: ST39140W Rev: > 1498 > Type: Direct-Access ANSI > SCSI revision: 02 > scsi0:A:0:0: Tagged Queuing enabled. Depth 4 > SCSI device sda: 17783240 512-byte hdwr sectors > (9105 MB) > SCSI device sda: drive cache: write back > sda: sda1 sda2 < sda5 sda6 sda7 > > Attached scsi disk sda at scsi0, channel 0, id 0, > lun 0 > Vendor: COMPAQ Model: BD009222C7 Rev: > B016 > Type: Direct-Access ANSI > SCSI revision: 02 > scsi0:A:1:0: Tagged Queuing enabled. Depth 4 > SCSI device sdb: 17773524 512-byte hdwr sectors > (9100 MB) > SCSI device sdb: drive cache: write back > sdb: sdb1 > Attached scsi disk sdb at scsi0, channel 0, id 1, > lun 0 > > > TIA > Satinder > > > > > --------------------------------- > Yahoo! India Matrimony: Find your partner now. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
