WKK wrote: > I have a Nagasaki IPC industrial computer that has an 8 GB flash drive > on a 44 pin ATA connector. I have booted FreeBSD 6.2 and 7.0 via a USB > CD drive and I am getting very bad read performance.
No wonder, your flash is incapable of DMA mode, at least on FreeBSD it seems. You are using PIO mode to transfer data. This degrades a modern pc to something like pre-pentium age. So unless you are able to get it working in DMA mode (UDMA33 will be fine, the slowest setting) you won't see any good performance and interrupt cpu usage will be extremely high. It will degrade your whole system. > The same CF device connected with a USB adapter (/dev/da0) gets about > 16MB/s In that case it is using DMA and not PIO. Maybe the USB adapter takes care of that? To have good flash performance you need an SSD with advanced controller chip. One example is Mtron Mobi/PRO Serial ATA SSD, which is pricey. Samsung and Transcend have new offerings too, but may offer less performance. SLC flash is better than MLC flash, but more expensive. And i suspect your flash device without controller chip to lack support of wear leveling technique, causing your flash to be weared out in just a couple of months of operation with a lot of writes in /var/log. You may enable soft updates with long update setting to delay this wearing effect. Regards, Veronica fluffles.net _______________________________________________ freebsd-hardware@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hardware To unsubscribe, send any mail to "[EMAIL PROTECTED]"
