> I think maybe it is "seek time" issue. ( 4 threads to access different So far, it seemed reasonable explanation:)
> files on non-contiguous blocks increases the seek time ) Maybe not. It should be related with the files location/distributing, which was readahead in booting process. The 'seek' derived from distributing rather than thread number, if distributing of file is continous, the throughput should be high. The thread influence should be limited. -----Original Message----- From: axel lin [mailto:[email protected]] Sent: 2009年3月3日 13:16 To: Zhang, Austin Cc: [email protected] Subject: Re: [Moblin Dev] Bootchart disk throughput 2009/3/3 Zhang, Austin <[email protected]>: > Are you using HDD? Yes. > Can you disable sreadahead and have a monitor again for the throughput? Test with sreadahead disabled, the Max Disk throughput is still 8MB/s. However, I got 12MB/s , If I modify the sreadahead source code to reduce the number of thread from 4 to only 1 thread. I think maybe it is "seek time" issue. ( 4 threads to access different files on non-contiguous blocks increases the seek time ) Regards, Axel > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of > axel lin > Sent: 2009年3月2日 7:41 > To: [email protected] > Subject: [Moblin Dev] Bootchart disk throughput > > hi list, > I checked my moblin2 bootchart and found the maximum disk throughput > is only 8MB/s, > However I got 25.21 MB/sec if I test with hdparm -tT /dev/sda. > Why the number is so much different between bootchart and hdparm test? > > Below shows my disk information: > -bash-3.2# hdparm -tT /dev/sda > > /dev/sda: > Timing cached reads: 756 MB in 2.00 seconds = 378.02 MB/sec > Timing buffered disk reads: 76 MB in 3.01 seconds = 25.21 MB/sec > -bash-3.2# > > -bash-3.2# hdparm -i /dev/sda > > /dev/sda: > > Model=TOSHIBA MK8009GAH , FwRev=BS011A , > SerialNo= 38B3W2NBW > Config={ Fixed } > RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=0 > BuffType=unknown, BuffSize=0kB, MaxMultSect=16, MultSect=?16? > CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=156301488 > IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120} > PIO modes: pio0 pio1 pio2 pio3 pio4 > DMA modes: sdma0 sdma1 sdma2 mdma0 mdma1 mdma2 > UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5 > AdvancedPM=yes: unknown setting WriteCache=enabled > Drive conforms to: Unspecified: ATA/ATAPI-1,2,3,4,5,6 > > * signifies the current active mode > > -bash-3.2# hdparm /dev/sda > > /dev/sda: > IO_support = 0 (default) > 16-bit) > HDIO_GET_UNMASKINTR failed: Inappropriate ioctl for device > HDIO_GET_DMA failed: Inappropriate ioctl for device > HDIO_GET_KEEPSETTINGS failed: Inappropriate ioctl for device > readonly = 0 (off) > readahead = 256 (on) > geometry = 9729/255/63, sectors = 156301488, start = 0 > > Regards, > Axel > _______________________________________________ > Moblin dev Mailing List > [email protected] > > To manage or unsubscribe from this mailing list visit: > https://lists.moblin.org/mailman/listinfo/dev or your user account on > http://moblin.org once logged in. > > For more information on the Moblin Developer Mailing lists visit: > http://moblin.org/community/mailing-lists > _______________________________________________ Moblin dev Mailing List [email protected] To manage or unsubscribe from this mailing list visit: https://lists.moblin.org/mailman/listinfo/dev or your user account on http://moblin.org once logged in. For more information on the Moblin Developer Mailing lists visit: http://moblin.org/community/mailing-lists
