Hi, Jens: I think this question belongs to your domain, but please let me know if I'm mistaken, so I can pursue this elsewhere.
I encountered a strange performance anomaly. I do the following: <----- Plug USB key [EMAIL PROTECTED] ~]# time dd if=/dev/uba of=/dev/null bs=10k count=10240 10240+0 records in 10240+0 records out real 0m22.731s user 0m0.004s sys 0m0.345s [EMAIL PROTECTED] ~]# <----- Remove and replug the USB key [EMAIL PROTECTED] ~]# time dd if=/dev/uba1 of=/dev/null bs=10k count=10240 10240+0 records in 10240+0 records out real 1m42.622s user 0m0.005s sys 0m1.518s [EMAIL PROTECTED] ~]# So, reading from a partition of the same device is 5 times slower than reading from the device itself. The question is, why? To the best of my knowledge, this does not occur with SCSI (usb-storage and sd or sr). This hints strongly that the ub is not doing something right, but what that can be? The ub takes the request processing machinery from Carmel exactly. I am wondering if Carmel (sx8) exhibits any similar performance anomalies (cc-ing to Jeff) Additional information: [EMAIL PROTECTED] ~]# cat /proc/version Linux version 2.6.11-rc4-lem ([EMAIL PROTECTED]) (gcc version 3.4.2 20041017 (Red Hat 3.4.2-6.fc3)) #1 Tue Feb 15 23:06:39 PST 2005 [EMAIL PROTECTED] ~]# cat /proc/partitions major minor #blocks name 3 0 39070080 hda 3 1 5935986 hda1 3 2 5936017 hda2 3 3 554242 hda3 3 4 1 hda4 3 5 26643771 hda5 180 0 1024000 uba 180 1 1023983 uba1 [EMAIL PROTECTED] ~]# Thanks, -- Pete - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
