On 8/28/06, Tejun Heo <htejun@xxxxxxxxx> wrote:
Hello, Derek Taubert wrote: > What doesn't work so well: > > 1) Writing to sda1. > > # dd if=/dev/zero of=/dev/sda1 count=4M > <ctrl-c, then wait 30 seconds> > 264205+0 records in > 264204+0 records out > 135272448 bytes (135 MB) copied, 111.373 seconds, 1.2 MB/s > > From iostat -k 10: > Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn > sda 2428.64 2422.46 667.66 24273 6690 > sda 36.84 23.72 1667.87 237 16662 > sda 2440.60 2434.90 616.00 24349 6160 > The read rate is curious (should be 0)...
Tejun already asked you to change the dd line, but I'm pretty sure it is the culprit, not a kernel bug. I always use a bs=4k arg for dd on x86 boxes. Not sure of the detais, but it often makes a huge performance change and eliminates all those wasteful reads. Greg -- Greg Freemyer The Norcross Group Forensics for the 21st Century - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
