> Benjamin LaHaise wrote:
O_DIRECT buffers must be aligned on block sized boundaries (minimum 512 bytes). Check the actual return code from the aiocb and you'll find that it is likely -EINVAL, no -EINPROGRESS. See the man page for posix_memalign() to properly align the pointer.
EEP!! I forgot all about buffer alignment!! Thanks for pointing it out :) ------------------ Two more questions. 1. Is aio_fsync of any use while 'aio_read'ing and 'aio_write'ing to a 'raw' device or a '/dev/sdb' with O_DIRECT? 2. I have an Ultra320 SCSI disk whose datasheet says it has a max. possible throughput of 78MBps I did a 'aio_write' onto '/dev/sdb' with O_DIRECT. Following are some throughput values. Buffer for IO | Avg Speed (in KBytes) | ----------------O----------- Upto 512KB | 69MBps 1024KB | 125MBps 2048KB | 250MBps 4096KB | 500MBps 8192KB | 1GBps -- What the !! -- Buffer cache does not come into consideration. Does this mean that the SCSI lower layer (aic79xx) can transfer data only upto 512 KB? - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
