> > > The problem is: FreeBSD is fast, but lacks of some special drivers. Linux has > all drivers but access to harddisk is unpredictable and thus unreliable! > What can I do??
there's several tunables you can do; 1) increase /sys/block/<device>/queue/nr_requests the linux default is on the low side 2) investigate other elevators; cfq is great for interactive use but not so great for max throughput. you can do this by echo'ing "deadline" into /sys/block/<device>/scheduler 3) make sure ext3 is set to "data=writeback"; the default journalling mode is very strict, fine for smallish files but for multi-gigabyte it'll start to hurt 4) try to use iostat -x /dev/<foo> 1 to see what values avg-rq and avg-qu are.. avg-rq should be at least several hundred if not more. 5) echo a larger value into /sys/block/<device>/queue/max_sectors_kb the default seems to be 512 which is... really low. The hw max is in another file in that directory; if you want max throughput set the max_sectors_kb value to the hw max. (you pay in terms of fairness for this; it's the eternal fairness/latency versus throughput tradeoff) - 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/
